/diy/ - Do It Yourself

How would I turn something like this into lab bench?
Also, will shit pop if I wind like 1 turn on current tranny and try using it as a spot welder

>>2444114
FAK.
I mean, why would you even convert such shit into lab bench?
Well, power mainly, shit can weld, cmon. Also high OCV so you can play with stuff like dunno, e-scooters or e-bike controllers

>>2444114
I'm not familiar with welder circuits, so if possible post a schematic of a similar welder at least. Or post all IC numbers. My thinking is that you may need to replace the control stage to prevent ramping and stuff, depending on whether it's digital or not. Getting it to really low voltages and currents might not be stable (or just be really noisy) with the existing feedback system. Also note that new circuitry may need to be sufficiently noise-hardened to withstand hundred amp spikes.

>e-bike controllers
Yeah that's why I also wanted a high-power benchtop PSU. Just bought some 100C lipos for $30 instead.

>>2444117
>I'm not familiar with welder circuits, so if possible post a schematic of a similar welder at least.
One dude reverse-eingineered a similar welder http://www.kit-shop.org/z/Welding_Inverter_Aka_Kasyan.zip

So it is a half-bridge (2 hv caps) and low-side is center-tapped thingy.
> Or post all IC numbers.
I dont really know which IC does it have, but I think it is a common PWM IC.
Feedback is kinda fucked on this, like lowest current I can get is just 15A.

I mean, on secondary side it would be a good idea to add capacitors and inductors, because output is 100% spicy, because i dont think welding electrode cares much about spikes.

Asking again because I forgot to check the last time I asked-

I need to nigger rig a set of headphones for a chinesium aux jack that expects pin 3 to be mono audio and pin 4 to be ground. Basically every set of headphones I can find are stereo.

Can I make stereo headphones work as mono by twisting together the left and right channel wires?

>>2444121
>Can I make stereo headphones work as mono by twisting together the left and right channel wires?
Yes you can.

Watch out, as if it wants an audio signal input, there may be a phantom power of ~2.5V with ~2.2kΩ ESR on that pin for the purpose of powering an electret microphone capsule. If there is, put an AC-pass cap on that line to improve fidelity. May also need to cut down the line volume, as electret mic inputs expect a pretty low volume.

>>2444122
It shouldn't, this is the pinout of the jack its expecting.

I want to use the headphones solely to listen to I have no need for the mic or ptt pins so I figure if I bought that replacement trrs jack I could just slip off the jack on a pair of cheap headphones, connect the left and right channel wires to the green wire/pin 3 in that replacement jack, and the ground of the headphones to the black wire/pin 4 of the replacement and just leave the first two pins unconnected

>>2444126
Ah I see what you're doing now. Yeah solder left and right directly to pin 3 (pin 2 in the second image), ground on the sleeve, and the top tip and ring just leave disconnected, it probably won't give phantom PTTs.

what CAD do you guys use? My classes made us use EAGLE and it makes me want to blow my brains out.
I'm trying to use Kicad, and maybe I'm just not used to/don't know the workflow yet, but the library system is annoying as hell

>>2444241
kicad's library system is ass but usable. I use it primarily because it's open source, but I've tried altium and it's not significantly better with regards to that.

>>2444111
Okay, stupid question here but I didn’t get answer in sqtdt

So I bought a spot welder at garage sale for $20 dollar bucks. Don’t need it, but I’ve needed a tiny spot welder for like 18650s and various NiMh packs (like for roomba).

I’m pretty sure this is over board for ting batteries, but can I wire up a huge resistor to make it useable for tiny battery tabs?

>>2444306
Like wire one of these ten dolla things

>>2444306
>>2444307
Maybe you will need to tame it down a bit. Like with variac or some shit. Or idk, triac chopper

What happens in terms of energy transfer when a small DC motor spins a large AC generator (with permanent magnets) that produces high voltage / high current? Since there is no free energy, how do we get this "power amplification"?

>>2444336
DC motor will slow down if you apply load.
Cant BTFO physics.

>>2444111 (chek'd)
Here are some of the more basic DIY electronic items you can make. I guess you can call this a lifehack:

Let's say you want to communicate with somebody, but you are in your house, don't have a cell phone or computer, so what do you do? There's two options:

Take an analog radio, cannibalize it into an aviation band receiver to listen to Air Traffic Control, air shows and other Civil Aviation Band transmissions through a set of simple modifications, set the frequency you need and turn the loudspeaker into a microphone and now you have an FM "Bug" transmitter. You can tune into any transmissions within your range and broadcast them through the microphone. You can call for help on cop cb radios and talk to other people who have one.

Or

Acoustic telephony. People have used tin cans with a string between both to talk as well as banging on pipes to communicate back and forth. In jails, inmates have been known to talk to the ladies upstairs through the toilets. How they do it is to take your mattress, take anything off of it (including the bedsheets and blankets), fold it in half, place it over the toilet bowl vertically and start pumping in and out with your knee as hard and fast as you can to sink the water to the bottom. Then you make a plug by taking a roll of toilet paper and wrapping it around your hand real fast for a couple seconds and twist it into a straight, thick wick, stuff it inside an empty Ramen soup bag and stick the rocket inside the hole that connects the sink to the toilet (using a rag will only soak through), then take either a blue plastic medicine cup that the nurse sometimes gives during med pass or take the styrofoam cup that comes with your trays, peel it in half, and use the lower half to scoop the remaining water out the bottom into the sink until it's empty, then knock on the inside of the toilet bowl, cup your hands around the bottom and shout to the people upstairs/downstairs.

>>2444354
Alternatively, you can take a styrofoam cup, peel out the bottom of the cup and stick it inside the toilet bowl to act as the microphone. This works because the pipes are interconnected and join in a t-shape and are made out of thick steel, so it'll send vibrations when you talk through it. I knew a guy on 1st floor who could talk to people on 2nd floor and the ladies on 3rd floor doing this. But just take note that it's also interconnected between cells also, so when your neighbor flushes, sometimes shit they flushed will turn up in your commode, so you'll just have to flush it and start over again. Optionally, you can use the vents. Just stand up on top of your sink if you're in the holding cells and bang and shout through the vent or if you're in the pods just walk up to your wall and bang and shout through the vent, because the rooms are a lot smaller in the pods. But as for the toilets, that's only something you can do in the winged areas. The vents are cell-to-cell, the toilets are floor-to-floor. I had one roommate who would take one of those hard trays and smack it against the ceiling on 2nd floorcso the girl he was dating above him could hear him.

>>2444111
I'm converting an old Ni-Cad tool to use an 18650 cell. This particular kit has a charger that outputs 3.6V. Is there a boost-converter charger board that can take 3-4 volts and boost it to charge a single lithium cell? Bonus points if it also has over-current and over-discharge protection.

(This is a nostalgia driven project so I'm willing to spend some money, but not a ludicrous amount.)

>>2444348
Can you elaborate? So a small DC motor as a prime mover is powered by an independent power supply and is connected to the shaft that spins the generator's rotor. Voltage appears on the stator windings. Now I connect load. Current starts flowing through the windings. What would make the rotor slow down? It doesn't affect the DC motor in any way, does it?

>>2444371
>What would make the rotor slow down? It doesn't affect the DC motor in any way, does it?

The electrical load will make the rotor harder to turn, and that means the independently powered DC motor will require more power to maintain the same speed.

Making the analogy larger, when you flip on a lightswitch in your house, that increase in electrical load goes all the way back to the steam turbine that's generating your power and slows it down just a tiny bit.

>>2444360
>I'm converting an old Ni-Cad tool to use an 18650 cell.

Update, I have it apart now, and it looks like I'll be able to fit in at least two 16340 cells and not have to modify the case.

Could I put a resistor on the ground after a fan? I want to increase load but not slow the fan down.

>>2444371
Go to uni, get electric machines and magnetism course.

>>2444306
Idk man, feels kinda dodgy to add external electronics without even looking at the internal stuff to see if you’ll damage it or if it’s easy to put through a variac. Also don’t you want two electrodes on the same side? Literally be easier to buy or make one of those $10 things than try to modify this beast.

>>2444371
Power P = V*I, but it’s also equal to torque τ multiplied by angular speed ω. In addition, magnetic field strength is directly proportional to current through a coil, and magnetic force is directly proportional to magnetic field strength, so a magnetic motor or generator has a linear relationship between torque and current. If you have a generator with no load, it will spin up to some no-load speed and draw very little current (just feeding ohmic losses). If you put a torque on the shaft, then that load will draw more current, and likely slow down the motor a bit too. The extreme condition is when you apply such a strong torque that the motor stalls, at which point the current flowing through the windings is insufficient to provide enough torque to spin it, as it is limited by the resistance of the motor. Generators act in the same way, but reversed. The faster a motor is, the higher the “back emf”, which is something to look into.

>>2444360
Honestly I’d just throw in a TP4056 and use it with a 5V wall adapter instead of a 3.6V one. Because lithium ion cells range from 3V to 4.2V, you’d need a buck-boost or SEPIC converter, in addition to a CC/CV charge circuit.
Put the two cells in parallel if you don’t want to fuck about with balancing and putting 2x the voltage into the motor.

>>2444401
What do you mean by “increase the load”? Because a series resistor will mean less current drawn AND will slow down the fan. If you want to draw more current then use a parallel resistor, but I can’t imagine why you’d want to increase the current drawn from a fan socket.

>>2444371
>>2444405
not necessary, simply get two lego motors and hook them together. spin one and observe. attach something to the axle of the other and try to spin again. truly a thing of beauty

I got a starlink I want to take camping for that sweet remote shitposting but didn't realize it'd be such an ordeal to power the damn thing
The thing uses ~50W when active
I'm aiming for being able to power it for 12hrs continuous, which I hope is good for a weekend trip

Solutions I've found imply LiFePo would weigh like 100lbs and cost north of $1500, highlighting how pathetic batteries are.
Strongly considering propane and propane accessories, but noise is sure to be an issue.
What do you guys think I should do?

>>2444451
Upgrade your alternator and put an extra battery in your trunk.

>>2444451
>The thing uses ~50W when active
>I'm aiming for being able to power it for 12hrs continuous, which I hope is good for a weekend trip

The Anker 757 PowerHouse would work with capacity to spare and is dead silent. The only bad thing is it weighs about the same as one of the little inverter generators and costs 4 times as much.

I *assume* weight isn't an issue given the size and mass of the Starlink kit.

>>2444455
heh one of my friends got stuck in his Prius might not be a bad idea to carry another
>>2444466
Oh yeah I've been seeing these make the rounds on youtube
It seems light enough, maybe I'll just go with this.
>starlink size
yeah it's a chonker
>weight
whole box was like 5lbs max
Honestly if they didn't integrate the power supply into the router I'd have gotten a DC power supply and been done with it

I'm a beginner learner to this stuff, I was wondering if any knowledgeable anons could answer a question I have regarding potentiometers.

What I'm building is a passive circuit to use as an expression pedal to be used for a guitar effect stompbox I have which has control voltage (CV) capabilities. More specifically it's going inside of a foot pedal enclosure, to be controlled by a treadle pot. Most schematics I've looked at suggest a B10K pot for this, but after reading about the difference between logarithmic and linear pots, I'm concerned that this will create some kind of bias toward the "heel" and "toe" while leaving the mid-range of the wiper ineffective. Is this the case or not? Should I use an A10K pot? Most schematics I've looked at suggest using a B pot for the treadle, but I've found a few that simply state 10K, and I'm concerned about being able to have accurate fine-tuning for what it's going to do (control the frequency rate for the oscillator inside of a ring modulator). Does a standard 10K pot have a log taper or no? Will I run into this problem if I use a linear taper pot? If anyone can help it would be greatly appreciated

>>2444420

So, a motor: at idle: similar to a transformer, low PF, mostly reactive load, current is low (magnetizing current), since speed is high, back emf is also high and roughly equals the input voltage. When load is applied, motor slows down and therfore magnetic field becomes weaker and as a result back emf goes down so current increases. Correct?
What about a generator: when it is idling, there is no current, voltage is high due to the EM field. But I am not sure what happens when load is applied. Current starts flowing, I imagine there will be some voltage sag.
So it is logical to imagine that prime mover will have to work harder. But why exactly?
>If you put a torque on the shaft,
I am confused if you are talking about a motor or a generator. Are you comparing the two devices, or you are talking about what happens in a motor that drives the generator in my imaginary setup?

>>2444380
>The electrical load will make the rotor harder to turn
why?

> increase in electrical load goes all the way back to the steam turbine that's generating your power and slows it down just a tiny bit.
i am sure it does. but why? in terms of voltage, current, back emf, EM field, etc.

>>2444491
Wait, so perhaps when current starts flowing in generator windings that creates mechanical force due to the Lorentz force and that force makes the prime move to work harder? Is there something about back emf in this story?

>>2444489
Audio circuits typically use log pots. Try both and see which you like better.

i need to add fans to my project for cooling. Where can I source the cheapest PC fans that are min. 120mm?

>>2444491
I think of a motor more as in:
>load torque increases
>speed goes down
>back emf is proportional to speed, so it goes down too
>lower back emf means more current can flow
>higher current means higher torque to counter the load torque
But that may be the same as what you described. Power factor isn't relevant when talking about a brushed DC motor, which is a nice simple case.
>generator
So, applying an electrical load to the generator's outputs? If you put a resistive load on there, the current through it will obey I = V/R. If the generator is spinning at a constant speed, then that more or less means that the voltage will be determined by that speed, so the current that flows comes from that. In reality, the resisting torque of the generator will likely slow down whatever is spinning the shaft, which means the voltage will be lower for higher output currents (lower resistances).

>I am confused if you are talking about a motor or a generator
Was talking about a load torque on a motor.

Also what you're describing is called a "rotary phase converter".

>>2444495
It's not Lorentz, it's more like Ampere's force law.
But yes, when current flows in the generator windings, that produces its own magnetic field that opposes the existing magnetic field. I can't really remember whether the full cancellation of the magnetic fields means stall condition or no-load condition, but I think it's the latter. For both a motor and generator, because they're effectively the same thing.

>>2444503
How many cfm do you need?
also aliexpress

Wooden thingy to keep 1/4" jacks in place for testing effects circuits. Wires are cat5 soldered (difficult— copper coating disintegrates easily) and also hot glued to the jacks. The signal leads go to a screw terminal block. The circuit on the breadboard is a "treble booster" found here: https://circuitdiagram.net/vox-treble-booster.html
I don't know how a treble booster is supposed to sound, but this one sounds very treble boosty, and noisy. The transistor was taken from a dead cfl ballast.

>>2444535
Might that transistor be a switching mosfet?

>>2444518
>If you put a resistive load
Yeah, and I am working up to my ultimate goal: to understand reactive power and why power companies are so obsessed with it. Vars and all that. They generate it, they distribute it, they absorb it and they say it is super important for them. I get reactive power in general, i.e. energy is stored either in the magnetic or the electric field but it is not converted to heat or any other type of energy and is returned back to the grid. And I don't get what it means. What if I have a 60Hz generator, and I have a resistive load of say 250 ohm. The current is flowing and the energy is converted to heat, and my turbine is spinning harder. Now imagine I connect a 10uF capacitor across the mains. Now what? The same current will flow in the circuit. But it is "reactive power" now. How will my turbine react? I am kinda guessing the generator will provide power for the first half period while energy is stored, but what happens in the other half period? The current is still flowing in the same direction... Any type of water analogy for this case? I read this document but it confused me even more.

>>2444552
No. Medium-power amplification NPN.

>>2444559
reactive power is pretty much just "dead weight" power. Before your AC waveform can do any useful work, it needs to generate the magnetic or electric field on the inductor/capacitor. Only then can it do what you want. However, even though it's dead weight, it's still power in excess of what's actually required for the circuit at hand, that the power company still needs to supply while, also doing nothing at all for the rest of the grid.
It's quite similar to hysteresis.

>>2444491
>>>2444380 (You)
>>The electrical load will make the rotor harder to turn
>why?

The magnetic field converts the electrical resistance into a mechanical resistance. On a deeper level, the rotor shaft is connected to the magnets. As these rotate, they cause a changing magnetic field in the coils. The changing magnetic field induces electrons to move in the coils. The resistors, as their name says, resists the movement of these electrons. The magnets that are trying to move these electrons "feel" this resistance in the form of increased torque.

>>2444559
>to understand reactive power
Ah.
>How will my turbine react?
Definitely an interesting question. Be sure you have a current/power monitor on the DC motor, as well as the frequency and current and voltage measurements for after the AC generator.

I'm pretty sure that the AC generator doesn't actually need to generate more power assuming ideal wires, but the extra reactive current flowing through the wires means a greater voltage drop through the wires, meaning more P = I^2*R wasted power, meaning the turbine actually does need to work harder. Transmission line losses really are rather significant, so bumping them up by 20% is something the power company would want to avoid.

3-phase motors and the like are inductive loads though, so I wonder if the power produced by a magnetic generator has some non-zero power factor.

>>2444588
Providing less resistance to electrons actually means more resisting torque in the generator (try shorting a motor out and trying to rotate it), so I'd consider that a bad analogy.

>>2444518
>cfm
honestly I did not think about this spec, instead I was going right to the size
>aliexpress
I was not seeing any deals there, thats why I figured I'd ask

I got a shit load of electric motors around, decent ones, thinking about buying some fan blades, maybe I can get something going with that

>>2444111
We have some ac stage stage lights with two cables for power in and power out. We routinely daisy chain them. One day when unplugging a daisy chain, sparks happened and now the lights don't work right. I took them apart and everything is working except the the power cables but I don't know where the fault is. THE FAULT IS NOT AT THE CONNECTIONS. When I move the cable around it will suddenly get a connection, but if I slightly move it again it looses connection. The only thing losing connection is the hot lead, the neutral and ground are fine. What the fuck is going on?

>>2444617
>What the fuck is going on?

come one. this is child's play to solve. using divide-and-conquer strategy.
you get someone to wiggle the wire and trace down the line until your ohmmeter (continuity beeper is best) tells you where the break is.
since wiggling can affect a long length of wire and etc, you need to tape down sections that have tested OK, so they cant move.
another option is the ''replace things one-by-one until it's fixed'' strategy.

If I add that dummy load to my dreamcast, would it heating up let toxic fumes from plastic/metal? It gets so hot, that it can melt the case if it touches it. Would adding a 4th resistor lower the temperature?

>>2444656
you need to stop, read more, and ask questions later
and quit modifying stuff, it ruins it

>>2444656
>Would adding a 4th resistor lower the temperature?

kinda, but it'd change the overall value, and you dont know what the consequences would be.

proper way to do it is to
- replace resistors by same value but larger wattage.
- place said resistors 1/2-inch above PCB, and separated from each other, so the fan can cool them better.

>>2444656
what mods you got going on there besides noctua mod and the gdemu?

>>2444656
why do people put power resistors inside a dreamcast in the first place?

>>2444675
something to do with the gdemu mod, you take out the disc drive but you have to do something with the power that was going to it, so people are passing it to ground, something like that

if I switch the brown and black wires, will this change the polarity of the fan? want the fan to blow away from the wood instead of into it

>>2444677
I'm not going to spend the time watching the youtube tutorial just yet (no non-video tutorials??), but that sounds like a really sub-optimal solution. Like, if it's a PSU that needs to be loaded to stop it floating high, then fix the PSU. If it's a current-sensor that throws a fit without sufficient load, swap out the current sense resistor.

>>2444679
Shaded pole motor? No it won't, there's no easy way to reverse those. Maybe you can try cutting the solid core copper wire from the stator and re-terminate them in a different orientation, maybe. You could also try to add a run winding into those slots to use with a capacitor (maybe a 100-1000nF X2 cap?), which you could reverse the polarity of, but no guarantees. If you do cut out the stator's copper loops, you can just start it in a desired direction by pushing it manually, probably.

>>2444679

no, nigger.
120Vac is symmetric.
fan has no way of knowing polarity.
if you DO WANT to reverse direction, you pull out the rotor and flip it top-to-bottom

>>2444662
People just say to put picopsu in but that has a more potential to ruin things and really hard to get to my country. Then they say to take the 12v regulator out, but that too causes problems. I just don't want my Pal dreamcast to burn.

>>2444674
Nothing yet, that ain't mine. I'm just putting gdemu in but I have a fear of overheating now that I want to solve. Noctua would be sweet, but im a 3rd world country loser and the 3d printed stuff wont be viable. Thinking about just changing the stock fan to a new 30mm just to ease things up.

>>2444694
i think that mod is a meme, maybe change the fan but you dont need the noctua, shit you are not going to be running it all day long for years

>>2444688
>but that sounds like a really sub-optimal solution. Like, if it's a PSU that needs to be loaded to stop it floating high, then fix the PSU. If it's a current-sensor that throws a fit without sufficient load, swap out the current sense resistor.
What I understood is that the 12v regulator is still up and runnimg, heating things up because nothing uses it anymore (the 12v used to power the gdrom drive motors) so putting resistors puts the load back and keeps it cooler. But the 12v is still used for videostuff etc so taking it completely off will most likely cause problems. If you change the psu to a smaller one with and external powerbrick, it might with bad luck cause the dreamcast video to be permanently glitched. I can't find any other solution than the resistors, but even that aint without problems.

>>2444696
>heating things up because nothing uses it anymore
What, is it a shunt regulator?

>>2444700
I don't really know, but that's what they say. Things get heated up because the 12v just idles there

>>2444700
>>2444705

>>2444721
Holy shit it is a shunt regulator. Though it's the zener, not the 2SSD1856 BJT, getting hot. Also that's an awful font due to how ambiguous the 1 is.
Personally I'd just swap that 1kΩ resistor for a larger one, which I don't think will impact any other part of the PSU.

>>2444724
like larger voltage or resistance?

>>2444724
Then again, decreased load could impact the other rails via goings on within the flyback transformer. Guess you can't just rewind it to have a few less turns on the 12V rail. I wouldn't expect it to be significant, but I may be wrong about that.

Maybe it's just to draw that 15V zener-made rail closer to 12V, in which case replacing it with a 13V zener may fix things. Or a TL431- or LM317-made rail, if you want to adjust it on the fly and stop having to have an expansive collection of zeners.

>>2444725
After looking at things some more, that zener will only be eating 0.3W at most, so I can't imagine it or the transistor is getting too hot. So a resistor change shouldn't affect anything. If the load resistance is designed to prevent other bad things from happening (e.g. on the other rails), as opposed to keeping the shunt regulator cool, I could understand it more.

>>2444728
>that zener will only be eating 0.3W at most, so I can't imagine it or the transistor is getting too hot.
Nobody really knows, I think, it's a collected assumption that there problem is there because it goes away with the resistor load or taking it out. Some say it's just placebo and a better airflow is just what you need.
I'd love to get the thing easily and painlessly dealt with, so after all this time and work the dc doesn't just melt while gaming for the first time.

>>2444730
Well it's definitely odd that it uses a 15V zener for a "12V" rail. Maybe if someone has a service manual I could check if it says there's a recommended voltage for that rail. Maybe it needs to be a bit higher or else the video shit can't regulate it down to a proper 12V. It isn't actually a shunt regulator due to that pass transistor, an increased load shouldn't change the output voltage much, it would decrease the power burnt by D4, but not by too much.

From https://www.delta-island.com/index.php/en/tutorials/gdemu-power-supply-mod
>In the absence of load on the rail the output voltage of the regulator reaches 14V This voltage is responsible for the temperature rise of the regulator.
This suggests it's a voltage increasing issue that could be fixed by swapping the zener to a 13-13.5V one. Using a regulator with better feedback would allow it to be used with or without the disc drive, but require more bodging/modification. But I don't really understand why that would cause the regulator circuit to heat up.

From https://www.reddit.com/r/dreamcast/comments/lkedsd/comment/gnjr50z/
>15V as you need to factor in the base-emitter voltage drop in the transistor, which according to the datasheet is 2V - quite high as it's a Darlington so there are actually two transistors to deal with
But even 2V Vbe doesn't account for the full 3V difference.

If it sitting there getting toasty with no load isn't an immediately fatal issue, I'd at least try swapping the zener, as it can't be worse than what it's currently doing or what it does when you remove the transistor entirely. Actually if you have a DMM, measure the voltage on the load-free regulator to see if it really does float up to 14V or so. So long as you don't put the zener in backwards.

>>2444738
>Using a regulator with better feedback would allow it to be used with or without the disc drive, but require more bodging/modification.
What would that include?

>>2444742
Maybe just a 7812 linear regulator? Pinouts allowing, you may be able to just drop one in as a replacement for the transistor, while replacing the zener with a wire and removing R16 entirely (or replacing it with a loading resistor if needed). But pinouts aren't allowing, because 7812 and all the other TO-220 linear regulators I've checked don't have their input pin in the middle. May just be able to twist them about though. You may be able to find a TO-220 12V regulator with the desired [GND, IN, OUT] pinout. Or a flipped pinout it if it doesn't need to be clamped to a heat-sink.

If it needs to be a bit higher like 13V, you may want to use an LM317 (will need a resistor from its output to its negative pin, can probably stretch one between the vacant holes of R33 and R16, replacing D4 with another resistor), or try to use a TL431 instead of D4 (even more bodging required). Putting a diode on a 12V regulator's ground leg may also bump your voltage up by 0.6V or so, at the expense of a well regulated output.

>>2444752
I'm a little torn between these possible solutions. The resistor load is easy and "safe" on the psu. The zener swap is possible and sounds pretty good on the long run. And the whole swap would probably be the most definite one, but loads of work.

this is going to sound fucktarded but how could i go about improvising a soldering iron tip if i just need to do a quick field expedient repair and cant wait for a replacement

>>2444764
Use an external PSU if you really want it to run cool.
>>2444789
Cut a conductor out of a length of Romex.

>>2444813
>Use an external PSU if you really want it to run cool.
meant for >>2444742

>>2444813
This could happen with the external psu mod, and it wont be fixed by changing back. I'd like to keep everything mostly stock so it functions correctly but wont overheat.

>>2444818
Can you explain the fault? Is the video glitch caused by overvoltage? Forgive my ignorance of all things Dreamcast.

>>2444821
I don't know either, but it's either emi or the videoswitches/calibrations fucking up due to the voltage not being stable or something like that. It might be rare or not even a real problem but I'm paranoid and it would cost me extra time and also a good amount of cash to get all the parts imported.

>>2444825
If you buck a laptop brick down to ~7.5V and run it through 5V and 3.3V regulators (with supporting passives), you should be just fine. The 12V is only used for the optical drive.

>>2444858
...or install a 5V USB-C trigger board and run that through 3.3V regulators. Then you need a USB-C PD supply/charger.

>>2444858
The 12v is also used for the video side for switches etc.

>>2444858
>>2444825
And thanks for the suggestions, but I still would like to go with the resistors and changing the zener, if they are safe regarding the melting of the case or metal or something else that would go wrong and be a hazard to my health. Breathing in burning plastic smoke aint my idea for a fun evening

>>2444870
>12v is also used for the video side
My eyes don't work so well. Do you see 12V anywhere on the schematic?
https://console5.com/wiki/Dreamcast#Schematics

>>2444862
>>2444858
>>2444874

>>2444878
If you take the 12v out the console can't go vga or scart anymore atleast, I don't know where that would be.

>>2444881
>can't go vga or scart anymore
Are you sure about that?
https://console5.com/techwiki/images/6/69/Dreamcast-VA0---4---Video.png

>>2444883
I'm not sure about anything, just relaying what I've read and heard. I don't know if there is a problem with taking the stuff out but I really don't want the risk. Same with the psu mod with fucking up the system completely might be rare as fuck, but I don't still like it.
https://youtu.be/Lk4Ydkh-QXg?t=581

>>2444885
Also at 5:40, why does he need to remove the resistor? Wouldn't cutting the transistor be enough?

>>2444881
One pin of the AV out connector is +12V.

>>2444889
Missed that. So it passes 12V through to the AV port. You could inject 12V at the TV side of the SCART connector and keep it isolated from the Dreamcast (no 12V connection between console and connector). Use a selector switch to select preset voltage divider resistors/aspect ratio mode.

>>2444889
The drive connector is the only other place that uses the +12V supply. There is no reason for that to be needed for anything other than SCART, which wants it as an aspect ratio signal. The VGA box doesn't use it.

>>2444901
I don't know then what people talked when they said vga was out.
>>2444899
So what should I do inside the console? Making real massive changes to the psu still has the video problem depicted here. >>2444818
Don't know what makes it go, bad powerbricks causing emi or something.
Should I just modify the 12v rail or take it out or what?

>>2444903
>So what should I do inside the console?
Use a laptop brick with a buck converter to bring the 19-20V down to 7.5V. Take that 7.5V to 5V and 3.3V regulators, and feed the output of each to their respective pins on the Dreamcast PSU header/connector.
Look up the datasheets for the regulators you'll be using and pay attention to the example circuits (copy them).

>>2444903
>Don't know what makes it go, bad powerbricks causing emi or something.
It could have been overvoltage from a supply higher than 12V, or a bad connection somewhere. Possibly a failing component, but the failure seems like it's GPU or VRAM related.

>>2444907
>higher than 12V
5V or 3.3V lmao

>>2444906
This might be too advanced for me but I'll look into it and (yet again) start ordering parts and stuff but what would be the best solution with the things I have so I get to play till I work out this new "psu".

>>2444911
>>2444906
Just get a mini itx psu, connect the 3.3v and 5v to the dreamcast connector and get a highquality 12v brick.

>>2444913
or that

What's the smallest Arduino compatible camera? I have the Seeeduino Xiao from SneedStudio which seems to be the smallest uc on the market, but the smallest camera I could find is substantially bigger.

Disclaimer: this is not for spying on girls in the shower

>>2444911
>best solution with the things I have
Do you have a small 12V fan? Use that as your load. Put a pot in series to control the speed.

>>2444919
Would one fan be enough load? I do have like 15 fans salvaged, one might be 12 v

>>2444919
and put a diode with the cathode on fan+ wire and anode on fan-
>>2444920
12V, 330mA is like 4W.

>>2444922
>and put a diode with the cathode on fan+ wire and anode on fan-
What would that help? Before or after the pot, and what size. Sorry I'm a retard beginner.

>>2444924
12V > series pot > parallel diode > fan

Orientation of the diode is important. Its purpose is to suppress back-EMF spikes when the field around the fan coil collapses (turns off).

>>2444922
I only have a 92mA 12v fan, shit. Gotta hunt for another one.
Where do I hook the pot ground

>>2444929
Ground is ground is ground. All roads lead to ground. There are three ground pins on the PSU header.

>>2444930
I was thinking that but I wanted to be sure. And I don't have a diode either, nice. I only have those zeners.

>>2444930
Sorry, I should say 0V because it's on the DC side. Ground is the AC side.
I'm being pedantic, but there is a distinction. Anyway, connect the pot to one of the three 0V pins on the PSU header (black wires).

>>2444932
Is the stock fan 12V? If it is, connect the other fan there so you won't need another diode.

>>2444933
No the stock fan is 5v, which is annoying.

>>2444934
Start hunting for Schottkys. Don't ruin anything that works to get it though.

Do you have a 12V LED strip? lmao

>>2444935
I may have.
If i'm ordering some diodes, do I need a new fan also to up the watts.

>>2444937
It's up to you, just don't go overboard. The 12V rail is meant for the GD-ROM drive (and passthrough to the AV port). I don't know how much current is drawn at full tilt, but stay below that. Guessing 1.2A.

>>2444945
So it doesn't matter? It doesn't again heat up the 12v rail.
>Diode, 1A, 100V, DO-15
Would this be enough?

>>2444947
That's fine. 1n4001?

>>2444957
SB1100

>>2444959
It'll work.

>>2444963
Thanks for your, and everyone else too, help. I've been searching for 2 weeks a good solution and now I think everything is atleast somewhat manageable.

>>2444967
No problem, fren. Better to take your time researching and asking questions now rather than later.

>>2444918

>>2444918
What about OV7725 or OV2640

>>2444906
>linear regulators
Mate those are garbage at reducing EMI. They have a peak ripple-rejection frequency of like 120Hz, they’re designed for mains ripple not SMPS ripple. If he does use an external PSU, he’ll need to use chokes and/or capacitance multipliers. Or zener-transistor regulators, which I think are good at ripple rejection at high-frequencies.

Still, subtly modifying the internal PSU a feels like a better solution compared to ditching it.

>>2444919
Oh this is good too, if you’re already putting a fan in there.

>>2444930
I wouldn’t connect it to a 0V pin at all, just making it a series resistance is enough.

>>2445032
Smallest one I know of is the pi camera. But you can probably find smaller ones on digi-key.

>>2445048
>I wouldn’t connect it to a 0V pin at all, just making it a series resistance is enough.
So it would be like this?

>>2445052
>>2445048

>>2445057
I'm a real polymath

>>2445042
I have something that size already, looking for something closer in size to the Sneeduino.

>>2445052
No, leave one end disconnected and use the other end plus the wiper

i want to test a car radiator fan that i believe is not working. i think the fan is rated anywhere from 15-30A, if i tested it with a 12v 3amp power supply the ps would just go kaput, right? i only ever tested small electrics like car radios and bulbs with a 12v 3a chink power supply i tore the plug off of so i'm still learnin ova hea

>>2445100
Sorry I don't understand

>>2445106

>>2445111
So how does that diode "suppress back-EMF spikes when the field around the fan coil collapses". I'm dumb and want to really know what is going on here so I wont screw it up.

>>2445120
When the fan turns off it creates a short voltage spike in the opposite polarity. The diode directs the discharge in one direction (i.e. the back-EMF becomes a forward discharge).

what is the bare min wire gauge for 120v ac?

>>2445153
Depends on the load, but it's more about insulation with mains voltage.

>>2442737
Hey, thanks anon. I got a nc flux and solder wire from mg chemicals and it is night and day difference. Didnt even need the flux while testing it. I had a shitty breadboard that was very hard to solder and even that was a breeze and no such 5m ohm resistance between pads even if i apply flux

I guess flux and solder is one thing to be not skimpy on

>>2445158
flux is almost more important, it can help even with some of the shittiest solder

>>2445158
>shitty breadboard that was very hard to solder

part of the difficulty was that your perboard was dull and dirty.
you gotta rub it until it's shiny and slick.
every male over 9 knows how to do that.

>>2445165
Here is an old pic. This is the other side of the board that i was not soldering on, the solder was not sticking and just was going through the hole

If it was because surface is unclean, it is still unclean but worked fine now. Iirc i tried scratching the surface with tools but didnt help much. I have a wire brush now

>>2444371
short the leads of any permanent magnet motor. brushed or brushless, doesn't matter. spin it slowly. notice how it's hard to turn? now spin it a faster. notice how it's even harder to turn?

>>2445158
You're welcome, Anon. Tell your friends.
>>2445172
>wire brush
Check out fiberglass scratch pens/brushes. It's similar to a magic eraser but lasts a long time unless you go around scratching everything with it like a tard.

>>2445177
thats pretty cool I switched from that green goop to nail polish. I will have to check that pen out

When I get home I’m going to try my home-made ferric chloride enchant. Once it’s finished I’ll try recycling it back into ferric chloride, or maybe into copper chloride. I figure keeping the current density nice and low won’t make any chlorine gas, so I’ll set it up under my bed for a few weeks and hope I don’t gas myself.

>>2445233
>ferric chloride enchant
Magic is fake and ghey, Anon.

>>2445172
>If it was because surface is unclean, it is still unclean but worked fine now.

here's your old pic.
it's definitely dull and dirty.
the copper should look as shiny as the solder blobs.
i use those Scotch-Brite dish pads, or steel wool when i feel dangerous.
if it works now it's coz the new flux (acid) is dissolving the dirt and oxidation.
as for your new pic, the lighting must be off coz i dont see any gold/copper color on anything.
looks like the pads were covered by white silk screen.
anyway, congratulations on your leveling up your skillz. another 80 levels and you'll be at 100 like me and my retard mom.

>>2445274
>my retard mom
That's not a very nice thing to say about the woman who shat you out of her snatch. She's at least level 101.

>>2445274
That pic is a different board. It solders a lot better compared the red one i posted

And it is dirty because the pic was taken long after i soldered that board and it was covered with the sticky mess the old flux did. When that pic was taken, all i did was adding that port at top right, which i brushed but i didnt clean the rest.

Silky things are me trying to clean it with cotton and alcohol

can a 14.8v lipo battery for an rc car be used to test 12v stuff or is that a little too high

>>2445331
Each cell is 4.1 or 4.2V at full charge.

>>2445331
Depends on the “12V stuff”. If it’s automotive, it’s probably fine as that stuff is usually 14V tolerant anyhow. A lot of other 12V stuff doesn’t really care about a volt or two too high, but you’d have to take it apart and read part numbers to be sure.

Also yeah as the other anon implied, 3S is a better 12V analogue than 4S. Measure the actual voltage before connecting anything.

>>2445335
>>2445349
i see, ty

So I plugged in values to an online 555 astable calculator. c1 = 10nf, r1 = 1k, r2 = 100. It tells me I should get 67.8 khz square wave with a 52% duty cycle. I put everything on a bread board and scope the output. 42.5 khz with a ~52% duty cycle. What gives? I've swapped out the 555, c1, r1 and r2 multiple times. Always ~42 khz.

>>2445401
Try it with 10 times the resistances and 1/10 times the capacitances. 100Ω feels too low for the discharge pin to sink via.

>>2445150
So the diode must be allowing current from the fan ground (minus) to fan 12v?

>>2445434
Yes.

>>2445468
Does the size of the potentiometer matter? Would it get hot

Is it possible to induce current into a pair of wire from afar? Lets say from no more than half a meter distance. The wire is 2-3 m long.
I was thinking about making a long high turn coil with its axis parallel to the wire, then pulsing a lot of current with the help of supercaps.

>>2444111
Holy digits

>>2445489
>Would it get hot
It will get warm like everything else, but you have a fan to cool it off.

>>2445068
Try this one:

https://www.waveshare.com/esp32-cam.htm#:~:text=The%20ESP32%2DCAM%20is%20a,QR%20identification%2C%20and%20so%20on.

Only problem is it comes with a load of extra crap but if you buy it just for the camera you'll be getting a pretty good deal

>>2445491
Yes, that's what a radio is. The question is how much power you need on the receiver

>>2445540
Not sure about the power.
I want to trip a GFCI relay on the "receiver".

>>2445543
>I want to trip a GFCI relay on the "receiver".

sounds like some MacGyver shit you're trying to pull.
if you wanna hurt someone remotely lemme make a suggestion.
take a microwave, remove doors, bypass the door switches, and irradiate the fucker to give 'em cancer.
(someone should add this to the list of projects to roll for)

Hi ohm. Noob here. I'm aiming to convert these normally closed solenoid valves into latching solenoid valves. Can someone explain to me (like I'm 5) the best way to go about this? Thanks pals.

>>2445639
Tried this and all I got was a lousy colonic steam cleaning.

>>2445640
you can use a separate latching relay to achieve the latching function.
https://new.abb.com/products/2TAZ312000R2011/e290-16-10-230

>>2445658
Thanks. Sorry for the amatuerish question, but won't the normally closed valve still draw current when it's latched open? My thinking was that it's best to hold it open with a permanent magnet..?

New to this board, but I was wondering if I could get help. I'm completely new to soldering, and I'm planning on replacing the battery on my GB and GBA games. This is probably going to be a one off, so I can't really justify spending like $100. I've narrowed it down to these two, and I'm wondering if they're too shitty for what I'm planning to do.

https://www.aliexpress.com/item/2251832616981204.html?spm=a2g0s.9042311.0.0.44b54c4dZeJHP9&gatewayAdapt=4itemAdapt

https://www.aliexpress.com/item/2251832758943018.html?gatewayAdapt=4itemAdapts

Any advice is appreciated.

>>2445670
You don't need a soldering station for this. You don't even need to regulate the temperature for this. Run down to your local hardware store and grab the first iron you can find. Alternatively, try to find a local hackerspace and visit on a social evening to borrow their iron and make friends while at it.

>>2445520
That looks perfect, thanks anon.

>>2445670
Get the cheapest one with temp control and high watt. They often come with some solder as well but if that is too shitty get a decent solder wire and flux

5th time is the charm /ohm/, right?

>>2445663
bumping

>>2445663
>won't the normally closed valve still draw current when it's latched open
Yes.
>My thinking was that it's best to hold it open with a permanent magnet..?
It may work, you'll have to test it. You'll also need to figure out some way of moving it in and out of position.

Here's something I could really used a big brain on. Have a precision 920 vacuum tube tester. The coil in the meter cooked and now it's basicallya brick. Trying to find a replacement is going to be complete ass. I'm autistic enough I dont .y rewinding this fucking thing by hand if it means a usable device. I understand accuracy is probably going to suffer but this is old equipment being good enough is all I care for. Anyone know how I can go about doing this?

>>2445663
The power cost to hold the relay and the valve open will be like £8 a year vs the permanent magnet which will be ~£5 + your time which will be £30 an hour for 2 hours so total cost of £65 for modifications
£65/£8 = 8 years and 2 months for you to save money by doing the modification.

If that's worth it for you, you've got bigger problems

>>2445775
Can you get a service manual, or is there some other calculation to figure out what the inductance needs to be? 90% chance you can buy an inductor with the right inductance and power rating from somewhere, but to get the same footprint you may well need to rewind what you've currently got.

>>2445841
I plan on rewinding it as it is basically a motor coil in a sense. I have the service manual but it doesnt go in depth about the meter just the device as a whole. It is basically an analog ammeter

>>2445792
What if there are 40 fast cycling valves being managed across 4 manifolds and they each draw 1.5A from the same board. Latching solenoids solve this problem. Always good to remember to consider whether your solution scales, pal. Also, these valves get extremely hot will not hold open after about 15 minutes. Damn, I was really expecting better quality responses from ohm.

>>2445849
If it's an ammeter at least it will be easy to calibrate. Get the same gauge of wire and the rest should follow quite simply.

>>2445910
If you add preload magnets you may be able to turn them on with less current, or even use them as latching relays with an H-bridge to switch the coils positive and negative. Actuation speed doesn't really matter for a valve as much as it does for a relay, but actuation force itself may matter, so you'll want to test to see if the relay can get dislodged from a latched state from vibration or sudden pulses of pressure or flow.

Could also use control valves instead of solenoid valves.

>>2445919
I don't think it'll be easy to convert these things. The way their built just doesn't really allow for it. I might just switch to motorized ball valves, even though they're more expensive.

>>2445922
Wish they weren't so expensive. I'd like to use them to keep shower water at exactly the same temperature, regardless of people using taps in the house.

>>2445849
>I plan on rewinding it

good luck with that!
you just need to know one thing: what is the current for full-scale deflection?
is it 50uA, 100uA, 250uA, 1mA?
once you know that you can just get a replacement with the same rating, and approx the same size.

- you can often alter the printed scale by printing one of your own and taping over the replacement's scale. or use photo of original
- if you cant open it to access the scale, print it on acetate and put on the outside
- if you cant get a unit with the right full-scale deflection current, you take a more sensitive unit and lower it's sensitivity with a parallel resistor.
- get with the fashion: buy digital panel unit for $5 from Ali-baby to measure voltage to 100V and current to 10A.
- feast your eyes on my $1 thrift store meter and try to not be envious.

I pretty much only work with low-voltage stuff so high voltage is a bit of a mystery to me.

I have a lava lamp that runs a bit too hot. I would like to be able to modulate the intensity of the lightbulb within. It's pretty much just a chord directly from mains into the lightbulb and back out again

I'm aware of something called a chopper circuit. Is that the simplest way to go about this?

>>2445933
>a chopper circuit.

yeah, it's called a light dimmer.
but a lava lamp works on heat, if you lower the temp, it's stops moving and that's hardly any fun to look at.

>>2445941
thank you, it looks like I have a project.

when they get too hot, the lava stops forming smooth globs and just turns into agitated little bubbles of grease, like in under-mixed salad dressing
I would rather be able to dim it a bit to cool it down, and then gradually bring it back up (thus maintaining the ambient light), rather than have to turn it off entirely and turn it back on

This is a distortion effect circuit built around a lm386. Why is there a 10 Ohm resistor in the power supply path?

>>2445953
>10 Ohm resistor in the power supply path?

reduces power consumption to make battery last longer.

>>2445953
>10 Ohm resistor in the power supply path?

reduces power consumption to make battery last longer.
the money you save can be applied to hookers and blow.

>>2445953
Might make the sound a bit warmer? Doubt it will impact power consumption significantly, you’d be better off changing the gain or load network if that was your aim.

>>2445953
If there's one chip I hate it's the lm386. Noisy, distorted, stupid pinout, sounds like shit.
There's a pedal that's supposed to sound like a Sunn amp, only it's just two lm386s and it sounds like shit.

>>2445919
>>2445931
I know it won't really work well but within 15% error is fine and the specs given were 400uA 160miliVolt so that's something to go on. The wire is roughly between 40 and 42 gauge have to measure to make sure. Really going to be a pain in the ass but is it possible to do is really what I am looking for. Without heavy modification nothing will fit the slot and this is old gear here keeping the look is the whole point.

>>2446005
Should be pretty easy to get within 5%. Just start winding with a coil that has the other end available to solder onto, so you can put a test current through it while you're still winding.

>>2446017
Sounds good shouldnt need to test it the whole time a bit of quick mathes measurements and coppers resistance per length should get me pretty close. If I over estimate it slightly all I'll need to do is trim. This is old equipment I wonder how it would function. But yeah I'll be happy if I can get 8%.

I just tried to calculate how much copper I dissolved in my etchant, assuming 1oz/sqft, and got 250ng. Which then turned into 8nmol, and then to 760µC of electrons. But that feels really low. So I'll just ignore those results, chuck a 100kΩ resistor in series with a 12V supply, and see if I get any copper on my electrode after a day. The intention is to see if I can reduce the copper without making chlorine gas.

Hi, I'm designing a partial hand prosthetic (half the hand and every finger except his thumb is missing) for one of my family friends and I'm a bit stuck on the stepper motor/DC motor with encoder/actuator front. I don't want to spend a lot of money for the first prototype and I never used stepper motors this small. I got overwhelmed by the chinese motors on ebay/ali/amazon and they don't really have proper documentation either like picrel. Could you please recommend me a sufficient motor that is small enough to fit 4 or more on the back of an adult male's hand but have the necessary torque to be usable to hold things with it?

I'm looking for a bench power supply. I can find numerous on amazon, but ideally I'd like one from a reputable manufacturer that won't detonate 5 minutes after plugging the thing in. What are your suggestions?

my oven broke. the heat wire on top stopped working so instead of buying a new oven i had a look inside, turns out you can just screw it out, so i ordered a replacement part, put it in and now it works again
holy shit i just repaired my oven for $10 and saved hundreds of dollars
this feels amazing to actually successfully repair something

Help a retard, these two are basically same right? All resistances are same. Other than more current flowing through single resistor, it should behave the same?

Gluing this inductor back to its sliding post. But how does this work exactly? Does to moving coil slide up and down and couple with the other ones inside? If I recall this slide is tied to a string along with another inductor in another box and that is threaded to the front of the radio. Might be the bass adjust dial not sure.

This is old school electronics so have to keep that in mind.

>>2446249
Of course I forgot the image.

>>2446154
1. avoid anything that looks like what you just posted like the plague.
2. Hanmatek if you want chink shit
3. Siglent if you want chink shit of actual quality

>>2446154
Do not get one of these. I have it cause it was free after I repaired it but it has some issues. 1 negative isnt isolated from main earth ground so the earth ground post is nearly pointless and theres 4volts ac on the output. Very dangerous for anything you plug into say your pc USB and using this supply together you'll get a short through both machines. Blew up an fpga this way. Its okay if you need voltages but shit other wise.

>>2446262
Forgot image but pic related.

>>2446237
>it should behave the same?

not even close.
top circuit has 1 diode-resistor path, coz 2 parallel diodes act as just 1 diode.
bottom circuit has 2 diode-resistor paths in parallel so it'll draw twice as much current.

>>2446262
>Its okay if you need voltages but shit other wise.

i have one and it's perfect, so YMMV.

how do metal detectors work?
say i take a 20cm diameter roll of paper and wrap a transformer wire around it 30 times to get a coil, what do i need to feed into this coild? ac? dc? low voltage or high? and what how does it change when metal object is present? does the voltage raise or something? or what do i need to look out for?

>>2446275
True but then I sk do you wanna risk putting down the money on a gamble like that?

>>2446283
>how do metal detectors work?

if you take a coil of wire and place a ferrous material within it, the inductance goes up.
way way up, like 400x if you do it just right.
so, if you put the coil in an oscillator, it'll change frequency when approaching ferrous metals.
you just need to detect that change using a beat oscillator.
or your ears, if you have some.

>>2446294
Would it work if I put a ferret in a slinky?

>>2446126
Take a look on LCSC to see if you find the same motors you’re seeing on alibay but with datasheets. Honestly I think going mechanical is going to be quicker and less of a hassle for the user, like what that YouTube Ian Davis guy does. Though definitely more of a pain to assemble.

I’d consider using solenoid actuators instead of motors, as they should be able to provide decent force at high-speed. Overvolted tiny BLDCs with lead-screws on them might be sufficiently fast, so long as you respect their thermal limits.

I have these old solar cells that I'd like to use in some project. They are rated at 12 V / 20 mA, so I might run them in parallel. What kind of enclosure should I build for them?

>>2446237
They act the same if the top resistor is half the value of the two bottom resistors.

>>2446249
I suspect what you’re describing is a variable inductor, and uses a piece of magnetic core material (e.g. ferrite) that slides back and forth inside the tube to change the inductance.

>>2446283
An actual metal detector works by having two intersecting coils whose geometries cancel out. A sine injected on one won’t be picked up by the other at all, until something enters the region near them, at which point a sine of some amplitude and phase will be detected by the sense coil. Using the phase you can determine whether the metal is ferromagnetic, paramagnetic, or diamagnetic, and how conductive they are to a lesser extent. Huygens Optics made a decent video on the topic, honestly they look quite easy to construct.

>>2446326
Are they weather-proof? If not you can just slap them on top of something with batteries or whatever underneath. Sheet metal, painted plywood, whatever floats your boat. The enclosure would more be determined by what you want to power with them. Like a weather station. Or a radio beacon. You’ll likely want to angle the panels at the equinox midday sun, but going a bit lower in the sky for more power in winter when the sun shines through more atmosphere, or even making a self-steering mechanism, could be options.

>>2446328
*if so*
If they’re not waterproof you’ll need to chuck them under a pane of glass.

>>2445953
Built it. It sounds very decent. Except nearing max gain or about 1/3 volume, which cause a very annoying high-pitched squeal.

>>2446352
That's the sound of oscillation.
My definition of "sounds decent" has come a long way since I was screwing around with lm386 chips.
I like NE5532 the best, and OPA2134 when I need jfet inputs.

>>2446355
And TL07x?

>>2446365
I think they're probably not much worse than an OPA2134 if at all, but IIRC they're a bit more restricting when it comes to voltage rails. Prefers wider ones.

>>2446022
>copper cathode gets oxidised to oblivion
Guess that's not enough current then. I'll try 10k series resistance, then 1k. About 0.5V was being dropped across the solution with 100kΩ, hope it doesn't increase too much, as going too high increases the chances of making chlorine gas.

>>2446390
>increases the chances of making chlorine gas.

Please to be telling me more about purchasing or manufacturing of such gas.
Please to be contacting me Muhammad.vonNeuman@gmail.com

>>2446355
I do own a Joyo clone of a tech21 Sansamp British unit for comparison and because I don't want to deal with a "real" tube amplifier. Nice units by the way. To me these diy distortion effects circuits are largely redundant because I have the really nice one which I paid money for. Not a lot, frankly. They're a lot cheaper than the originals. From what I was able to gather the circuit I built is sold as a stompbox under the name "Lovepedal Purple Plexi" and gets high ratings online so I thought it was worth a shot since it's a simple circuit.

>>2446417
>They're a lot cheaper than the originals
Okay but my point remains: you should use precision, low-noise, low-distortion op-amps in order to achieve the very lowest distortion possible on your distortion pedals.
Also make sure to use dual polarity power supplies to avoid being buried in asymmetry.

I have a small computer that won't turn on anymore. The power button is supposed to turn orange if plugged in and off, but it doesn't even do that when I plug in the 19V power brick.
I moved the power thing to another outlet and used my multimeter to measure the inside vs the outside of the barrel plug. Reads ~19.5V. If I then plug it in the computer, then take it out, and do the reading again, the barrel plug only reads ~1V. I have to pull the power and reconnect and it goes back to reading around 19V.
Is this indicative of a bad power brick?
I don't know a lot about electronics so I'm not sure what I'm seeing when the voltage output from the brick drops to 1V.

>>2446546
Do a continuity test on the switch, then look in all the ports for shorted pins. Use a flashlight and magnifying glass if you have to. If it's still dead you'll need to examine the motherboard. Remove everything except the CPU and RAM and try to power on.

>>2446546
>Is this indicative of a bad power brick?
It's indicative of a short. The power brick's short-circuit protection kills the output until the power is cycled.

>>2446546
>Is this indicative of a bad power brick?

that's the most obvious reason: a sickly power brick.
another possibility is the computer has a short, and the power brick shuts down for it's own protection, and only resets after you cycle it.
fortunately, pretty much every laptop uses 17V-20V power, so borrowing a replacement to test things should be easy.

>>2446554
>>2446551
thanks anons, I'm going to bed but I'll try to find the short tomorrow

>>2446556
Cool beans. Just to clarify, the power brick is behaving as it should. The problem is in the NUC somewhere.

>>2446417
They certainly are fun to try when you already have the parts in your bin. The pedal I was shitting on is the earthquaker acapulco gold, btw. It has 2x lm386 into a volume knob.
>>2446465
Diodes are for clipping, if I wanted an opamp to do the work I'd use my RAT.

Does anyone know what's going on here?
I'm trying to read a PAS sensor with an Arduino and it only works while I'm measuring it with a multimeter between Signal and 5V wires like pic rel.
If I remove the multimeter, Arduino never gets to read the signal. It works even if I just let the multimeter turned off, so maybe I need some resistor or something? I know no shit about electronics.

What I'm trying to do: https://endless-sphere.com/forums/viewtopic.php?t=87116

Relevant Arduino code:
attachInterrupt(digitalPinToInterrupt(2), pulse, RISING);
void pulse() {
Serial.println("pulse");
}

>>2446628
99% sure you need to enable the internal pullup

>>2446632
>pinMode(2, INPUT);
I think I did, or at least I think it's that line.

>>2446632
>>2446635
Oh shit, it's INPUT_PULLUP.
Thanks Anon, you're right. It works now :)

One more thing in case anyone knows... It gets interrupted whenever I spin the wheel, doesn't matter if it forward or backward. Can I get it to detect only forward somehow? I think it's because the sensor is shit.

>>2446635
>pinMode
I prefer to use PORTB.etc. = etc. or whatever it is for the older AVRs. Closer to what's actually going on beneath the gunk.

>>2446637
Without interpreting the protocol (gotta do that after the interrupt) there's no real way of figuring out whether it's going up or down. Assuming it's digital. If it's analogue like PPM or PWM then maybe you can do it with a 555 or two, but digital is generally going to be easier.

>probably killed the power mosfet
shucks

>>2446656
just learn toner transfer, or get a mill or just spend five bucks on jlcpcb. these shitty caveman pcbs trigger me.

>>2446658
>toner transfer
imagine not having solder mask
Also I don't have a laser printer, and the inkjet transparency method is more of a hassle.
Also also this is literally the last board I'll ever have to hand-paint if it works, because it's the power supply for an LCD photo-masking lightbox.

>>2446556
>>2446559
Godspeed and report back!

Is it safe to file FR2 pcb? I didn't get the copper out another way and the board got filed too.

>>2444111
How do I make a PCB at home? Toner transfer sucks balls, it never transfers properly. Hand drawing with marker is turbo-autist territory and not really possible with smaller parts like SOT-563.
I've heard good things about using photoresist film. I've also heard that I do not have to use a laser printer with transparent sheet but I can just use normal inkjet on paper and use oil to make paper transparent for UV exposure. Is this possible?
I have sunk thousands of dollars to my country's version of JLCPCB (but only very slow and expensive). Minimum order quantity is 10 so I have to order 9 extra boards if I only ever need 1

What kind of setup would I need to solder cleanly in my apartment? It's just one room plus kitchen and a bathroom so I really don't want toxic smoke or piece of solder flying every where.

>>2446694
I don't solder a lot, and I have a hepa air purifier with a carbon filter. I used that to suck up the smoke and it seemed to do fine. If you're just doing some small jobs, I'd imagine something like that, or an open window with a fan, or the range hood on your stove would be fine.

>>2446782
I don't think the smoke even is that bad an issue if you don't do it as a job.

>>2446694
Nothing, soldering is not welding, flux fumes are just pine rosin, which is no problem unless you solder whole day. If you indeed solder whole day, you can get extractors with filter or just a simple fan.
>>2446677
Sanding fiberglass sucks, do not breathe that stuff in.
Sanding phenolic paper is sucks too, but seems less bad.
Which one is FR2 - the fuck i know.
>>2446681
>How do I make a PCB at home? Toner transfer sucks balls, it never transfers properly
Get special paper (or well, backing from sticker), it transfers 99% of traces even 0.15 mm thin and you can always fix it with sharpie.
Get a new toner cartridge and drum.
Instead of heating give a try to solvent or acetone.
Photo-resist is also an option, but I have never done it, because it seems like a pain.
After all, some people mill PCBs on CNC.

>>2446801
Its phenolic paper, how bad is it then? I didnt get too much out but still

>>2446801
>>2446825
Fucking hell I'm panicking now. I only filed like a 1cm long, a mm deep and wide channel to the board. Didn't breathe that hard but didn't avoid it either.

>>2446828
Why weren't you wearing your eyemuffs and earglasses? Why didn't you wear your covids face paper?

>>2446832
I didn't know I needed any of those, I'm a fucking retard. Am I going to get fucking cancer now

>>2446828
It's as bad as breathing in gypsum or starch and rust is more dangerous. Dont go snorting it but once or twice in small doses wont do anything. In the worst case, you get asthma or something, not cancer.

>>2446835
Meh, it takes a lot of exposure to get cancer.
Also, you can use a bit of water to lower the dust level.

>>2446846
Well it's too late now for watering

>>2446849
Just breathe the water in and give your lungs a douche. Don't forget the vinegar.

>>2446851
I did take a shower, I don't know if that helped

>>2446855
It made it worse, Anon. Everyone knows not to shower after breathing in silica dust. Now you're gonna grow another hole in your butt.

Hey hey guys, I am a noob in rf and I have a couple of questions. I am trying to make a simple telecomunications application and I want to multiply two signals, one low pass let's say up to 100MHz and a sine of about 2.4GHz. What multiplier/mixer circuit to use for that? I have no idea. Also what's a good way of generating that sine? It might need to be some value up to 2.5GHz but once I come up with the value it won't change (i.e. it might be 2.41 but once decided it won't need to change ever again so I would want a sine of 2.41). Also I have no idea about how you connect an antenna, do you just plug it in the wire with the voltage signal that you want to transmit or do you but some resistance or something?

>>2446856
I don't care about holes, if I still live

>>2446858
You'll be fine.

>>2446859
Are you sure, people say it's super fucking dangerous stuff

>>2446860
Did you snort it like cocaine? Use a neti pot if you're that worried about it.

>>2446865
I didn't but I was just standing there normally and just filing away.
Does neti pot clean lungs?

>>2446868
It flushes out your sinus cavity.

>>2446869
Is my sinuses in danger?

>>2446872
No, but if you have shit stuck to your mucus membranes it could drain into your lungs and stomach.

>>2446874
Well thats nice, I don't have one. Fucking shit how am I supposed to get sleep now

>>2446681
Buy a 2nd hand MSLA 3D printer and use the UV light + LCD for exposing PCBs. Or make an equivalent. Other options are a laser cutter to burn off etch resist, and a router.

>>2446857
For a mixer, the HackRF One uses this:
https://www.qorvo.com/products/p/RFFC5072
As for a sine, you’re often best off making a square wave and filtering the shit out of it. Much easier to control frequency that way. Sine oscillators aren’t too hard to make, especially with the help of a good inverting amplifier, but it’s not easy to control their amplitude so they often undergo clipping.

>>2446884
>As for a sine, you’re often best off making a square wave and filtering the shit out of it.
How would I do that though? Do I need high frequency op amps? I don't think a microprocessor would be able to do this since it would need a very high clock speed

>>2446661
>>2446546
Here's some pics of the switch.
I hooked up another 19V adapter with the same polarity, and this one wasn't quite as smart. After a second or two connected, I saw a small amount of magic smoke. I immediately disconnected but I wonder how much damage I did.. I think the smoke was coming from the power switch area, but I wasn't sure. Note that these pics are taken before that incident, though I don't notice any difference after.
I visually inspected the ports and don't find anything weird. I looked over both sides of the board, looking for blown out components, and I don't see anything. However, there is some brown gunk below the switch, and the contacts on the underside look a little rough. It's definitely suspicious.

A-B show 16kohm resistance, dropping to 0 when I press the power.
C-D show 0ohm and continuity, but it looks like a shield that wraps around the entire thing (see the front view). Maybe that's just part of the ground plane and acts like the outside of ports?

Here are the readings for the contacts on the bottom side of the switch.
1-2 0
1-3 3.8 kohms, no change when I press power
1-4 15.5 kohms. drops to 0 if I press power
1-5 0
2-3 3.8, no change
2-4 15.5, drops to 0 if i press power
2-5 0
3-4 19 kohms, drops to 3.8 if i press power
3-5 3.8
4-5 15.5, drops to 0 if i press power

If I put one probe on the inside of the power port, and the other on random components, it basically always reads 400kohms.

>>2446880
>how am I supposed to get sleep now
Count sheep or something. You're overreacting, Anon. Everything will be okay.

>>2446898
I'm an insane ocd faggot and can't handle things like this.

>>2446901
Think of all the people whose lungs turned into mortar after the WTC towers fell. You (possibly) inhaled a few tiny specks of dust. Don't be a puss.

>>2446907
How do i can use those parts and boarda now, if they have some of the dust on them now

>>2446912
Take it outside and brush it off or blast it with compressed air. Wear a helmet and duct tape it to your neck so you get a good seal.

>>2446916
I did wipe it before I soldered

>>2446921
imagine the smell

>>2446923
I'm constantly smelling it and feeling shit in my lungs, I hate my life

>>2446931
>I hate my life
Do drugs and sex with whores.

>>2446939
Can't, I'm afraid of the sun and walking on grass. Doing anything like that would be absolutely crippling

>>2446887
Multipole cascaded RC filters.

>>2446942
>walking on grass
>crippling
Quite the paradox. Ride a bike. lmao

>>2446956
I mean I could get ticks or something like that from grass. That is enough to ruin a day, drugs, tobacco etc. would make me catatonic for weeks.

>>2446953
I was mostly talking about how to generate a high frequency square wave...

>>2446825
Isn't that stuff in plywood and other commonly cut and sanded things?

>>2446960
You reminded me of "The Boy in the Plastic Bubble". It's the story of how John Travolta became a climate scientologist.

>>2446976
It's more like the Monk, except less counting stuff and none of the intelligence

>>2446969
>Fine dust produced by the process is dangerous if inhaled into the lungs. Use a mask when milling phenolic plywood .
That doesn't help at all

>>2446995
It's the wood that's harmful and not the phenolic film

Sorry for the bad angle, I hope it is visible. What is the name of this connector/plug type?

>>2447068
JST
Give me $1000.

>>2447073
thanks

>>2447074
yw

My key FOB stopped working even with a new battery and contact cleaning. took a look inside and saw what could be a dead leaked capacitor. Any way to ID it and replace it, or just get a replacement fob? Car is about 20 years old

>>2447078
Good news is that it didn't leak (it's ceramic).

>>2447078
Take a short piece of stripped wire and short the button pins manually to simulate button clicks. It's probably a bad tact switch or a dead crystal/oscillator.

>>2446962
Si5351 is the old favourite for generating almost arbitrary frequencies up to 160MHz. But for GHz range, you may find yourself constructing some sort of meme diode oscillator. As a part of a PLL for control, I'd guess. If you just want a fixed frequency, chances are you can buy a MEMS oscillator at exactly your chosen frequency and be done with it. Hope you're good at microwave board design!

>>2447125
ye olde favourite tavyrne

what the fuck have i done

>>2447153
You crossed the streams.

>>2447153
>drain of 60V transistor now getting up to 84V
it never fucking ends

trying to figure out how the remote for my ceiling fan works so that i can make additional remotes/ integrate with other gadgets. the chip encodes the remote ID and the command in a 12 bit burst, over what seems like a bogus tunable antenna. I traced everything out (single layer pcb) and the circuit makes no sense to me but I don't know anything about transmitters. can anyone explain how this works? the antenna looks weird (it's like two turns of wire?) and the bits in the stream are like 1ms wide which I feel like should be way too slow for rf coupling out of an antenna.

>>2447185
sorry forgot a wire across the antenna (L)

>>2447187
trying too hard to do the captcha to remember to attach the file

>>2447189
If you have an arduino you might be able to capture the signals using the iron library then use it to recreate the signals for other remotes.

I built another distortion circuit and I can pick up a fairly clean local radio signal.

>>2447199
i already have the waveform and the logic for making the burst, but i don't know how to wirelessly transmit it. i kind of assumed the signal was switching the coil via the transistor but after beeping out the pcb it doesnt look like it's doing that so i'm confused on the transmitting part.

>>2444724
>that 2sd1856 pass transistor
just replace that basted with a LM7812 or some switching regulator equivalent

>>2447206
here is an overlay. Vcc is filtered via L1 and then split across both sides of the green antenna coil?

>>2447214

looks like a classic cheapo low-power RF transmitter without crystal.
with 2 turns on the coil, i'd say it's around 100-300Mhz.

>>2447219
the no crystal definitely was confusing me too but I guess it's just the LC resonance that is the carrier? 300 MHz nice, bang on. i'm still learning about RF so this is a little foreign to me but i have enough info now to redesign the circuit.

Could one of you be a champ and tell me which connector this is?

>>2447326
the header has these guide slots in the sides.

>>2444111
Is it possible to power LEDS in series with 120v AC?

>>2447219
what does two turns on the coil do as opposed to 3 or 4?

>>2447326
>>2447068
NOW KISS

>>2447338
Yes, either with a capacitive dropper or some of these:
https://datasheet.lcsc.com/lcsc/1807312050_Shenzhen-Sunmoon-Micro-SM2082GA_C241847.pdf
https://datasheet.lcsc.com/lcsc/2202131830_KIWI-KP18001WPA_C2692495.pdf
But only the chinks make those ICs.

>>2447326
>>2447340
mine isn't jst

>>2447340
holy shit the SM2082GA is the datasheet I am looking at rn, just never knew you could do it..

>>2447342
Yeah I made a board with that IC once. But I overestimated my mains voltage (240V instead of 230V) and the resulting load is too high a voltage for the mains to supply. Hence this circuit: >>2447153, a 12V to 350V flyback converter, that also doesn't work. So be sure to look at the minimum dropout voltage and give it a sufficiently wide berth.
On the off-chance you haven't already, check out Big Clive's YouTube channel for all the mains LEDs he looks at, a lot of the cheaper newer ones use those ICs and reverse engineers their schematics.

I prefer the KP18001 for having a built-in bridge rectifier, though it is a lower power IC and the thermal pad will be impossible to solder to an aluminium-backed PCB without a hotplate.

>>2447326
>>2447335
Turns out it's a CKM 25440101-4P

>>2447125
>Hope you're good at microwave board design!
I have no idea about microwave design. Quick rundown or reasources?

I'm planning a tiny robot contest.
Since it's gonna be extremely inexpensive and the participants don't have any idea about building robots I'm gonna give them a PCB as a base with pre soldered motors and ball transfer unit on the tip.

I'm also planning to add a motor with either vertical or horizontal mounts to weaponize it.

Do you guys think this is a good design to give to someone and tell them to make a battle bot around it?


Kinda like: Here, it moves, you have a month to make it kill.

>>2447375
Also, what wire with 6 cables is less likely to get in the way?

>>2447375
In what ways might the weapon motor be used? Flippers are all I can think of (high speed spinners/blades are likely not going to be very effective or very safe), but those would need position feedback to reset properly. Are they 3D printing the mechanical stuff like bellcranks and gears?

>wired
Telling them to try out communication protocols across a cheap 433MHz module might be fun, but it may be over their heads.

>>2447376
I'd go for a really flexible silicone wires on a tall post to keep it out of the way, if you have to use wires.

>>2447380
433Mhz coms are way over their heads.
Maybe I could set it up but it may make the project more expensive than I envisioned since I want to make 10-20, do you have a cheap example of an implementation?

What you mention about the weapon is definitely true, not safe and not effective I may be able to implement 3D printed actuators...

>>2447339
>what does two turns on the coil do as opposed to 3 or 4?

determines the inductance of the coil, and thus the frequency of the oscillator as per attached formula.
with experience, you can tell the approx frequency from the number of turns, given the typical capacitor values used in such circuits.

>>2447384
>>2447380
>>2447375
Here's a pretty similar design, I'm interested in the gearbox motors since my original idea was simply running the motors thru resistors to make them slower, this wouldn't sacrifce torque.

Trying to aliexpress myself some 30 low RPM 3v gearboxed motors for these robots.

This reddit post mentions 1000RPM but I guess they're running the mtoros through a controller, I just want to plug straight 3v on-off, does 60-100RPM sound better?

https://www.reddit.com/r/battlebots/comments/fg06zt/whats_a_standard_wheel_rpm_and_movement_speed_for/

>>2447384
>433Mhz coms are way over their heads.
Well if it's a programming task anyhow I'd say it's perfectly fine, otherwise yeah you're probably right. Those 433MHz modules are like 50c, though you would need to prevent the controllers from interfering somehow. An idea would be to just have two receiver-transceiver pairs, at different frequencies, and plug them into the boards of the bots that are battling. That way the price of the radio units doesn't really matter as much as you don't need one for each bot and controller.

As for the weapons, servo-based flippers are easy but don't have much variety. Instead I'd see about making some sort of multi-purpose bot, like for picking up boxes and stacking them. The task would be to make a multi-purpose bot, with the actual task unknown, so you have to plan for versatility. Another thought would be a cooperative task of some sort. Something with eggs?

>>2447392
If you're doing servos anyhow, you should have the signal complexity to make simple PWM circuits with an L298 or other cheap H-bridge. Those gearmotors should have sufficient torque, if in doubt figure out what speed that many RPMs means for a wheel of that radius. If it's pretty slow the torque should be more than decent. You can also hopefully figure out torque from a datasheet (idk maybe you can find the same motor on LCSC, if not Sparkfun or Adafruit).

>>2447394
Man, that's smart, I should make some task with eggs, carrying eggs or putting eggs in a basket, and then have them fight, in the end for fun

>>2447398
Throw eggs, whisk eggs, flip an omelette, the sky’s the limit with eggs.

>>2447404
>the sky’s the limit
eggs in spaaaaaace

I have a MC (pic10f322) that runs on batteries. When I also connect this 5v voltage regulator to same battery, MC resets

This is the regulator
https://www.pololu.com/product/2562

Why would that be? I feel like regulator shorts the battery for a split second or something, because if short it myself, that also resets the MC obviously.

Why would that be? If so anything I can do about it?

brown out reset is disabled. Also the regulator is not connected to anything and draws very little current (as far as I can observe, maybe it short circuits initially and draws large amount of currents)

>>2447466
What is the battery voltage?

>>2447471
3 nimh battery, about 3.9v right now. it is within the range of MC and the voltage regulator. both works fine individually with those batteries, it is just the moment I connect the regulator, MC resets. And works fine after that. So whatever is happening is happening during the initial connection

>>2447466
Just looked at the regulator link ($25 USD for a boost converter?!) and saw the following:
>In our tests with typical power leads (~30″ test clips), input voltages above 4.5 V caused voltage spikes that could potentially damage the regulator. You can suppress such spikes by soldering a 33 μF or larger electrolytic capacitor close to the regulator between VIN and GND.
They left out a cap and still want $25 for something that costs fiddy cent.

>>2447474
Can you suggest any alternatives? One that generates a stable 5v out of an input voltage that can vary a little

J5019 modules combine a TP4056 single-cell lithium battery charger with a MT3608 boost converter that can output between 4.3-27VDC, 7W max. You can bypass the TP4056 and just use the boost converter if you want. Can be modified with bigger caps and larger inductor to put out more continuous current.

>>2447476
sorry
>>2447478

Are my lungs gone and board covered with toxic dust because I filed it down. I can't relax at all because of it

>>2447488
Back in the old days the school administration would have recommended Ritalin therapy to your parents. That's the Gen-x version of Adderall. It always struck me as counterintuitive to give amphetamines to high-strung people, but authority knows best, right? lmao

>>2447490
I already have drugs to ease my mind, but they don't help with these acute situations, just takes the edge off my daily life so I get out of bed and can eat.

>>2447488
Have you ever filed metal? That's as bad as filing some pcb.

>>2447495
Have you ever been to a sandy beach? You inhaled more dust while you were throwing horseshoes and drinking shitty beer in midday sun for 4 hours.

>>2447501
Yeah but it isn't toxic, carcinogenic, dustshit like that phenolic formaldehyde

>>2447505
You should build a safety helmet with blinky LEDs and a tarduino connected to a raspberry pee connected to a raspberry peepeeko connected to a STM32 connected to a 555 that turns your helmet fan on and off.

>>2447513
and write your 3000 lines of code in peethon. It should be connected to the innernets so you can ask Sari questions about safety datasheets and OSHA requirements.

>>2447517
>connected to the innernets
bootoof

>>2447513
I can't do that because I can't make any boards. And it wont help when my lungs are already gone

>>2447520
Is this some kind of guerilla marketing campaign for Xi's PCBs?

>>2447522
No, I'm just a fucking neurotic loser and can't sleep because of my fear now.

>>2447525
I gotta look up the number for Dr. Mike Huckabee. He can get you hooked up with a lifetime supply of Relaxium Sleep™.

or you could try some Fentanyl® - sleep hard!

>>2447531
I could sleep if I could get some closure on this problem

>>2447537
problem: closed
go to sleep

>>2447539
It's not, how badly have I ruined my health? Is my workroom now contaminated? How much of the phenolic formaldehyde is bad, how much a small file gets out etc

>>2447542
>how badly have I ruined my health?
If you don't go to bed you'll go blind.
>Is my workroom now contaminated?
There's more fecal particles in your workroom than phenolic formaldehyde resin.
>How much of the phenolic formaldehyde is bad
In a liquid or solid state? Look up the MSDS.

>>2447543
Solid, in a pcb fr2.

>>2447545
>SKIN: Contact may cause allergic skin reactions. SKIN ABSORPTION: Skin absorption is unlikely to occur due to the physical form of the product. INGESTION: May be harmful if swallowed. INHALATION: Dust particles may cause respiratory tract irritation, coughing and wheezing.

>>2447547
Why do people then say it's like asbestos

>>2447550
I don't know why people say the things they do.

>>2447550
FR2 is paper and phenolic resin. FR4 is fiberglass and epoxy.

>>2447558
I know, and its the phenolic resin that worries me

>>2447561
Worrying all the time takes 42 years off of your life expectancy. Do you worry about being worried?

>>2447570
I do, it's all bad

>>2447575
https://www.youtube.com/watch?v=d-diB65scQU

>>2447583
Can't, these accidents happen if I'm not vigilant. Still can't go near my components because they were in my workroom when i filed.

>>2447488
Just vacuum it up.

>>2447716
Dust mites are crippling.

From WWVB radio guidelines:
>The RF bandwidth of the receiver should be narrow, typically ±10 Hz or less.
How the hell can you make it so narrow? At 60K that requires Q=6000. But a typical inductance of a ferrite loopstick antenna used in atomic clock radios is on the order of hundreds of uH. And according to my calculations, L should be at least 15mH. Where am I wrong?

>>2447727
I think where I am wrong is this: I let R=1 for simplicity so of course a thicker wire could be used, so Q could be made higher regardless of the inductance value.
But there is also antenna radiation resistance in series with R, that can also be a factor that could reduce Q. And I don't know what a typical value could be. But if it is >1ohm then I am back to square one.

>>2447727
Why 60k? Presumably you're going to mix your signal down and could use a filter with a lower center frequency

Where do you guys buy cheap transformers? I want to make a ~72VDC 5A power supply with 120VAC input, so I figure my flyback converter will need a 350VA transformer. But they're $100+ on McMaster and Digikey, which seems ludicrous for a bunch of copper wound together with a slug of iron in the middle. Or is the problem that the flyback allows the use of a lower-rated transformer than I think?

I am converting a vintage camcorder to use a lithium ion battery instead of the old lead-acid battery which came with the camera. It's from 1989: Panasonic OmniMovie X6 CCD. Has anyone done a similar battery conversion?

I opened the camera and cut out the original battery terminals, then soldered the wires to output from a lithium pack I got. The camera functions with this battery, but dies within 1 minute as the camera reads a very low battery level (it's charged). The lithium pack I had on hand is less capacity than the original battery. Could this be why the camera thinks its level is low? My understanding is that the camera reads voltage level to determine how much battery life remains, but perhaps the power draw is too great for the smaller capacity battery.

These are the battery specifications
Original: 12V 2300 mAh lead acid
New: 12.6V 1800 mAh Li ion

Camera power consumption per manual
On battery: 12 V DC 14W (max 24W)
On AC adapter: 40 W

>>2447751
Goodwill. Just bought me this 600W AVR for $3.99. It has a nice hefty tranny in it. And the case can be used a s project box. Although those AVRs are rare, there are also step up / step down 220/110 transformers that you can find for cheap at Goodwill or on Craigslist. But they are also becoming rare.

>>2447727
>How the hell can you make it so narrow?

it's only a recommendation to increase sensitivity.
it's not a requirement.
impossible things are never required, unless you have a wife.

>>2447762
>It has a nice hefty tranny in it.

not sure that's appropriate as those tend to be 12V to 120V transformers.
72Vdc is a long ways away.
i'd go for a thrift store vintage stereo of 200W - 300W which should have a beefy transformer in the right range: 120Vac to 60Vac center tap.

>>2447751
Flyback transformers and AC mains transformers are entirely different beasts. Since the frequency is much higher, you can have a much lower inductance. Also you need an air-gap in its core to prevent saturation, according to big-air-gap. They act like boost converters, so the actual voltage the primary side gets up to is higher than rectified mains, so the windings ratio you want will be skewed appropriately (say, 200:72 instead of 170:72). Naturally, your switching transistor will need to handle that too.
Not sure how to find flyback transformers on Digi-Key but they will be there. The only problem is finding one with the right windings. Make sure the switching controller you choose is designed for mains usage (off-line).

>>2447752
Incompatible voltage levels. If having one more series cell would be too high a voltage at max charge, you’ll need to add a DC-DC converter.

>>2445676
>>2445695

Thank you Anons, it was actually braindead easy. Really happy with how it came out.

>>2447807
Well this particular one turned out to be shit but for a different reason: laminations are welded just like on a MOT so it is not worth messing with and I shitcanned it. But sizewise it is a nice 600W transformer. Damn shame it is not serviceable.

>those tend to be 12V to 120V transformers.
They tend to be 220 to 110 auto transformers of various sizes but it doesn't matter as long as they are big enough for your required wattage. Of course you may need to buy magnetic wire separately according to your amperage but it is still cheaper than buying a brand new transformer. I typically salvage and reuse at least some of the copper.

>>2447809
>>2447840
Oh I didn't realize that anon needed a flyback. I though he was talking about power transformers.

I'm making a 5v sensor that's output signal is coming from an lm3900 opamp. What is a good size resistor to put inline to keep the opamp safe? 1k too big?

>>2447847
Read the maximum continuous output current from the datasheet, and do R ≥ 5V/I

>>2447849
ty

>>2447840
>They tend to be 220 to 110 auto transformers of various sizes

oh, that looked like a UPS to me.
with AVR being the british spelling.

>>2447716
From my lungs ?

Hi Anons, EEE internfag working for RD Department here I have some problems. So what I am supposed to design a PCB with a 42V-30V entry and passing from a knife fuse to
two seperate LM-2596 and turning to 5V and 24V. After that two seperate voltages are supposed to pass various different LC and TVS and in the end come to the terminal. So my questions are:
-How am I supposed to assign the wires for entry? I have done a design like pic related but I am not sure if its good. My design is that there are two different entry sockets and they allign together to enter the knife fuse. And then they seperate to enter their own LM-2596. I think my design is wrong how should I correct it?
- How am I supposed to make these two LM2596 to give two different voltages? I do know that I am supposed to use resistors but which ones to be precise? And how much voltage should enter to 24V and 5V (seperately)? They want a subsistent and precise 24V and 5V, how am I supposed to decrease the voltage to this absolute two different precise values that my buck converters work flawless? This seems impossible to be honest.
-Why do we use LC and TVS?

>>2447960
forgot picrel

>>2447960
>How am I supposed to make these two LM2596 to give two different voltages?

you get the 5V version for 5V and the adjustable version for 24V

>supposed to use resistors but which ones to be precise?

download the datasheet from TI and read pages 27-29.
it takes you thru the math step-by-step.

in fact the datasheet is ALWAYS the thing you check first, even before 4chan.

>>2447960
>there are two different entry sockets

as for that part, i dont follow at all.
but it's very important to realize that if you have 2 separate incoming voltages, you cant just parallel them.
the stronger one will kill the weaker.
you gotta use a diode on each line to create a wired-OR circuit.
google it.

>>2447965
By two seperate sockets I meant this, so I am supposed to add diodes in front of them, thank you.
>>2447964
>you get the 5V version for 5V and the adjustable version for 24V
The thing is that we already have LM-2596HVS made so I can't change their versions. Both of the LM2596 are the same
>download the datasheet from TI and read pages 27-29. it takes you thru the math step-by-step.
That is what I would do if they weren't already made. My problem remains

>>2447968
>already made
What do you have, ebay modules? If so there are schematics for those depending on how many pots are on it, pic related is the 2-pot. If on the other hand it's some professional dev-board, then you should be able to find the files for it on the website of whoever made it, if not on wherever it was purchased from. If there's a low-side current-sense resistor (like in pic related) then you may have difficulty connecting the output grounds together.

As for filtration, personally I'm of mind to chuck a capacitance multiplier before the feedback voltage divider, which may still be an option if you're desoldering THT trimpots. With a choke before it. But if a Vbe drop means too much heat, then an LC filter may be necessary. The L should probably be a choke, not a low-loss inductor. Figure out the specs of your loads and plan accordingly. Specs like voltage ripple tolerance, current draw, and any current intermittency. If the load current will suddenly change you'll be limited more in what size chokes you can use, and will want larger caps.

For the input diodes, if the input current is higher than 1-5A I'd consider using P-channel MOSFET circuits instead of diodes.

Also why the fuck do you have VCC going to some shared node and the other pin (Presumably power, aka VCC) going to the inputs of the voltage converters? Please put more than 5s of effort into it.
No more harm than necessary meant, but how did you get this job thrown on you?

>>2447973
>No more harm than necessary meant, but how did you get this job thrown on you?
Well our boss is just different, he wants us to learn everything by ourselves and he corrects the mistakes we make. It's kind of weird way of teaching but I have learned a bit to be honest.
Also we have put more effort than 5 seconds its just we are rookies and we have many flaws. So as it turns out there is a potentiometer above the already made LM2596 so they can be adjusted to be 24V and 5V. For now I am trying to make a schematic of the card and trying to connect varristors and TVS's.

>>2448014
>So as it turns out there is a potentiometer above the already made LM2596 so they can be adjusted to be 24V and 5V
I'd consider desoldering it in favour of a fixed voltage divider just so it can't be tampered with, but a dab of loctite works fine as well. You do have the option of adding a capacitance multiplier between the voltage output and the feedback loop using that trimpot's holes, which you may want to consider if one of the two rails needs to be particularly free of high-frequency noise. Definitely calculate the ripple rejection from the planned LC filter either way.

Also see this site, it has a schematic linked at the bottom of the page:
https://www.hotmcu.com/lm2596-buck-dcdc-module-p-50.html
It's a very common module and people have done the dirty work before you. This person also reverse engineered one:
http://www.kerrywong.com/2015/07/24/lm2596-dc-dc-converter-module-testing/
And they look the same at a glance, so the values like the 10kΩ trimpot and 470Ω resistor are probably correct.

>>2445153
https://youtu.be/3m5qxZm_JqM?t=64

>>2447875
AVR is a voltage regulator. Not the same as UPS. All it does it reacts to voltage fluctuations in your power system and adjusts voltage as needed but within a small range.

>>2444111
Digital electronics teacher keeps recommending me "an investigation of the laws of thought", saying it's the base for anything electronic. It it worth the time?

>>2448553
No clue what it is, but it sounds like a semi philosophical angle at how empirical reasoning, and by extension the scientific method, makes engineering possible. I doubt you’d need a whole book for that, but it sounds like an interesting read and if you have no background in the sciences I would recommend something like it. The key insights that lead from ancient philosophy to modern science are something I personally find fascinating and not to be taken for granted. Read it on libgen if you do want to pick it up or just give it a skim and it’s asking for textbook pricing. Also be sure that your teacher isn’t a co-author trying to augment his income by recommending irrelevant tripe.

>>2448585
Book was written by George Boole. He was basically trying to quantify "how humans think" and inadvertently completely changed the way we see automation systems today (read from the summary).
I'm getting my technician's degree in electrical systems, so this stuff is very new to me(always liked electronics though).

>>2448754
>>2448754
>>2448754
NEW THREAD