/diy/ - Do It Yourself

Can anyone tell me why when a power supply goes bad it starts pulsing?
Got a LED from china and it came with its own power supply, so cool, whatever, I plug it in, wire everything up, and the thing works for maybe five seconds of me briefly plugging it in to test it before I solder the LED to the heatsink, but once it's all done the thing starts blinking.
I've had this happen before whenever a power supply I get is lower rated than what it's supposed to be, so
>Buy a 10W LED with a "10W" power supply that's really only 3W
>Plug that shit in
>The nigga dies and starts blinking

The extent of my knowledge is watching big Clive videos and 10 years of tinkering.


tl;dr:
What's the DEEAEEEeAAAALLLL with switch mode power supplies?
Wait, I only googled "Power supply blinking". Imma google "Switch mode power supply blinking"
Nope, doesn't really help. Just that it might be doing that to sense if there's a draw.
So the current detection might be fucked?

>>1115120
Okay /g/ stupid here
I am trying to make my atmega32 work with a 16x2 LCD, the standard JHD162A. Now on the internet people say it needs a high to low pulse to make it work, does that mean the pulse needs to be

HIGH all the time, LOW, then HIGH again

or

LOW all the time, HIGH, then LOW again

>>1115157
On enable? The latter. See the datasheet or copy someone else's code.

>>1115153

it's simplicity itself: the power supply is constantly checking if the output voltage is at the right level. when you suck more current then it's capable of giving, this monitoring circuit says ''whoa, voltage too low, too much current'' and it shuts down the output temporarily. then it tries it again to see if the problem is gone, and since it isnt, it repeats.

>>1115157
>HIGH all the time, LOW, then HIGH again

this one.

>>1115161
It does the same when connected to a multi meter though.

>>1115161
>>1115165
Oh jesus fuck.
So the power supply was shitting out 42V, I just assumed the LED would be a 42V LED then.
Good news, by some miracle, the LED's fine.
Bad news is it starts up just the same on 12V.
So the power supply was fucked from the beginning. Didn't seem to do too much damage to the LED though.
This is a nightmare

>>1115168
NOW it's running on 12V and fucking smoking for some reason.
Fucking shit.
>Forward Voltage: 9-11V
WHO HAS FUCKING 11V POWER SUPPLIES?
Shit.

>>1115170
>WHO HAS FUCKING 11V POWER SUPPLIES?

12V supply with a diode in series becomes 11.3V; two diodes becomes 10.6V

>>1115203
>Using a diode to drop current
That's cheating anon, but also totally brilliant.
ANYWAY, I soldered the LED to my metal work shelf to use as a heatsink, and running it at 12v gets the whole thing hot enough to melt the solder in like three seconds.
How thick of a heatsink do you usually need for a 10W LED?
Or is running it that extra volt over doing the damage?
Fuck this, I'm dropping it to 9V

>>1115228
>Fuck this, I'm dropping it to 9V

You shouldn't be controlling the voltage (within reason)
You should be limiting the current to the specified level or below.

I'm wanting to make some LED lighting to go in my vehicle. The electrical system generally runs between 12-15V depending on load and whether or not my engine is running.

I was looking at these 3W LEDs: https://www.aliexpress.com/item/Freeshipping-10PCS-1W-3W-High-Power-LED-Chip-light-bead-emitter-Cool-White-Warm-White-Red/2036054930.html
>90-120 Lumens
>2.0-2.6vdc
>700mA

Now I've never dealt with any high power LEDs like this before. How do I run them safely? How much heat do they generate? Do I need a heat sink for these little ones or can I tuck the LEDs into a little housing all alone? Do I choose resistors based on my maximum voltage of 15 or would that make them not work very well if they drop to 12v? Since I apparently need an 8W resistor, does that mean it needs to be exactly 8W or at least 8W?

what do you think about this soldering station?
https://www.aliexpress.com/item/HAKKO-FX-951-fx951-Digital-Soldering-Station-set-kit-Electric-soldering-iron-set-kit-75W-Replace/32441796375.html
i know it's just a knockoff, as i read pretty honest one, but i want to know your opinion

>>1115228

You seem to be under the impression that LEDs are voltage mode components. They aren't. An ideal LED only needs sufficient voltage to turn on, and will then draw an infinite amount of current if not limited.

In reality, LEDs (especially larger ones) have parasitic effects that complicate this. In a nutshell, however, a small increase in voltage will lead to a large increase in current. Thus, LEDs need to be driven by a constant-current supply (a power supply that varies voltage to regulate current), not a constant-voltage supply (a power supply that varies current to regulate voltage).

Will low-power LEDs (in the mW range), you can use a resistor in series with the LED in order to make it behave more like a resistive load, but this gets very wasteful and impractical with higher-powered modules.

Also, I'm assuming your "metal work shelf" is steel, which is a poor conductor of heat. Your LED needs to be attached to a proper aluminum or copper heatsink.

> it's an anons do not understand LEDs thread

every fucking time

Hey guys, what soldering iron do You use? I wanna buy some station, or just soldering pen (dunno how to call it).
But I have like no idea what wattage and what brand should I take. Any advice please?

>>1115391
pls help. Do I need to buy a real heat sink for a little 1W LED or does the attached 20mm pcb dissipate enough heat?

Also if I run a little below the max current will they stay cooler? I've tried googling this shit but can't find any answers.

>>1115288
I'd get a BUCK stepdown converter from ebay that has a current limiter and voltage limiter, then set them up with that. Depending on how you set the converter you may need heatsinks, for full power operation you almost certainly need heatsinks. Keep an eye out for the amp and wattage ratings of the converter

>>1115390
>>1115235
WAIT, so for everything else I've ever dealt with it's "Lol just use whatever power supply you want, doesn't matter if it's 20A, if your component only wants to draw 500mA that's fine, it'll just draw what it wants and everything will be fine!"
But for LED's I need a power supply that gives them a reasonable voltage but also limits their current to whatever the LED's specifically need to run?
I buy a fucking 10W supply, it's a 3W and shits itself.
I buy a 20w, it's a 15W and my LED melts a hole to the center of the earth.

>>1115474
yes

>>1115474

yes

the amount of current a resistive load wants depends on the voltage

>>1115481
>>1115484
Thanks guys, seriously, thanks for helping someone as stupid as me. I really do appreciate it.

Last dumbshit question:
So say I have 2x 10W LED's and a 20W power supply, I have the LED's plugged in in parallel, they're each getting 900mA or whatever, so taking up the full 20W.
If I unplugged one of them, the other would fry, right?

But now I'm looking up drivers, 20W's are still 900MA, but at 24V. 50W are closer to 50V, with 2-3A.
Do I have to run the led's in series AND in parallel to satisfy this shit? So two in series to get the voltage up to 24V or whatever, and then the same thing beside it to get the current draw to suit?

>>1115406
Top: Dremel VersaTip
Middle: Goot KS-30R
Bottom: Soldron 25W

I use the middle one. The "genuine made in japan weeb iron"

>>1115521
If the power supply is a constant current supply then it will need to output double the current required by one led to power two. If its set to output double the current and you disconnect one led the other led will get double the current and will be sad
If one of the leds breaks then it has essential taken itself out of the circuit and so the other led will still be sad. You see that running parallel led on a constant current supply can be tricky.

A constant current supply is only constant current because it varies it's own voltage to keep the current where it needs to be. You can put as many leds as you want in series as long as the total voltage doesn't exceed the maximum voltage the driver can produce.
You can put chains in parallel but then if any single led breaks then that leg of the series circuit will probably go open circuit and the entire current will pass through half of the leds and they will be sad again. Thevenin did a pretty good job of explaining voltage and currents in series and parallel so google him of you want to learn.

>>1115521
There are variations between individual LEDs and LED assemblies.
If you attempt to connect them in series or parallel they may not operate as designed.
When LEDs used in home wiring most electricians call the power supply a 'ballast'
This is because fluorescent fixtures use a ballast for the same purpose - to limit current.
(the ballast has other functions but let's not get sidetracked)
The 'power supply' for a 120vac LED string usually looks like a 'brick' with wires - just like a ballast.
Some companies even describe them as ballasts.
More specifically they are called LED Drivers so they aren't confused with 'power supplies'
Each LED Driver is designed for specific wattage and number of LEDs it supports.
To operate your LEDs properly, you should give each one it's own driver of the proper rating or find a driver than can operate single or multiple LEDs of the same wattage simultaneously.

>>1115542
>Some companies even describe them as ballasts.
http://www.prweb.com/releases/2011/02/prweb5100754.htm

>>1115540
Cheers, that helps a lot.
Imma look up Thevenin
>>1115542
Shit, I've been using LED driver and power supply interchangeably, I guess I need to get it in my head that they're completely different things then.
>Each LED Driver is designed for specific wattage and number of LEDs it supports.
Gotcha, this clarifies everything perfectly.
No mixing and matching (kinda) get the driver(s) that match what you're doing perfectly.

So I'm trying to make a prototype led cube display. Rather than soldering LEDs on to bus wire, I want to print the circuit on glass sheets with surface mount LEDs and the. Adhere the glass slates together forming what looks like a solid glass cube with LEDs floating inside of it. I have a few questions I haven't been able to Google I figured I'd ask here.

Can I buy surface mount LEDs with minimal packaging? I want to try and make this as dense as possible. I have some VLSI design experience so it might be work printing the led die on the glass. The biggest problem here is adhering to the glass I guess and I don't know of my manufacturers that would custom print on glass cheaply. I know how to make PCBs on glass, but this is an entirely different ballpark.

Secondly, assuming I get them on the glass sheets what would be the best way to adhere clear glass slates to each other while still maintaining its transparency? I was thinking about using clear polycarbonate like they do with airplane windows and windshields but I'm not sure how hard that would be to diy.

Appreciate the feedback!

>>1116085
Then* many*

Should've proof read before posting.

Can anyone recommend a good way of testing 18650 cell discharge? Or recommend 3500mah cells that are in fact 3500mah and not some knock off chinese shit?

Made my first electric thing. Little stun gun type deal. I understand I should also be able to use this to make a small emp device, I know I need to connect one end of a copper wire coil to one high voltage cable, I understand I need to have the other end not directly connected to the other hv output but there needs to be a spark gap. I'm trying to get my head around having some way to disconnect the coil from the hv output via a switch or something that won't let it just ark where it wants and I would like another led to indicate when the coil is connected. How the balls?

My other option I think would to have the coil connect with some connectors I can just disconnect and not bother with the indicator light, but I'd like to overcomplicate things.

Also do resistor values really matter that much with leds? I am using a 9 volt battery, it destroys the leds with no protection but a 1k resistor seems to protect them. Should I be using a higher capacity one? Lower? I'm very new to this stuff.

>>1116172
I think I will just ditch the indicator led and use a gpio female cable and a pin instead of a switch that could get all arky. Is there some component that acts as a self contained spark gap? I'd rather not just have it be a cable stuck down near another one. Would it be a bad idea to use a switch/button as a spark gap? Will it make it go up in smoke with all the angry electrics in it? I haven't released any magic smoke just yet.

>>1116085
Maybe vapor deposition on glass? Never tried to buy LED bare dies but they must be available somewhere. Hope you can wirebond

>>1116172

With small LEDs if it works it's good enough

>>1116172

A switch will probably work

How do I mathematically model a finite grid of resistors for a computer simulation?

I'm not autistic enough to try to simulate that one question that involves an infinite grid, I want to see if I can simulate the effects in this picture by varying resistance of resistors as they dissipate power

I want to use real electricity equations, so I need to vary the resistance of each resistor continuously. Basically I want to do what LTspice does but only for 1 component: a resistor (maybe you can consider it to be a thermistor that gains resistance as it gets hotter)

>>1116268
Kirchhoff's laws give you a system of linear equations, which you can then solve.

Brute-force application of Kirchhoff's laws tends to result in redundant equations. You can either eliminate these or use a least-squares solver (e.g. numpy.linalg.lstsq).

But for an M*N rectangular grid, it's easy enough to get the right set of equations. KCL gives you M*N equations, KVL on the "cells" gives you (M-1)*(N-1), which is 2*M*N-M-N+1 equations. You have M*(N-1)+(M-1)*N resistor currents plus the supply current, which is 2*M*N-M-N+1 unknowns.

>>1116268
Lichtenberg figures are primarily an issue of capacitance. Earthing a point results in a local field strength which exceeds break-down. This causes resistance to decrease, which causes nearby capacitors to discharge, lowering the voltage at those point, effectively causing the set of grounded points to spread outward.

The fundamental mechanism is that each capacitor will only discharge once. If there are multiple adjacent nodes at ground potential, it will discharge into one of them at random. This is what causes the tree structure (i.e. the graph is acyclic).

>>1115120
it seems as though school wouldn't have taught me much just given me more handson experience at a higher cost. any idea where i can take free certification tests?

>>1115530
top one looks like the holy grail of soldering irons.

>connect to a power supply and use a multimeter to test wires for polarity
wat do if ac adaptor wires? plugging into mains with the jack end of the cord hacked off like it is sounds like a good way to electrocute myself

>>1116085
0402 size LEDs (about 1 x 0.5mm) are everyday stuff and 0201 (about 0.6 x 0.4mm) are available from Digi-key etc.
It sounds like the wiring will be much more visible than the LEDs even with those normal solderable LEDs, though.

Quartz is occasionally used as a PCB material, but it's not cheap. Plastic would be a more common choice in application like yours, but the wiring will be even more visible and it isn't really a material for one-off protos. And then you can fantasize about making your own glass PCBs, but that's going to be a massive pain in the ass, if you want them to look good.

IMO you should seriously consider alternative ways to produce the visual effect you want.

>>1116449
I've printed on glass before, it's not as bad as people seem to think.

I can't really achieve the same visual effect any other way. Well, short of inventing holograms ..

https://www.amazon.co.uk/gp/product/B01N4D3YN5/ref=oh_aui_detailpage_o08_s00?ie=UTF8&psc=1

is there a way to connect an led to the output of this? or will it make it go bang no matter the resistor value?

400kv sounds pretty high

Getting into electronics as a hobby, since there are so few tools you really need to buy, I'm going to spoil myself on the ones I do get. Which style do y'all prefer for wire strippers, and who makes the best ones? What about wire cutters?

>>1116453
Well, if someone else provides the equipment and materials, you can make the metalization thick enough that it won't dissolve in solder and you can use solderable metal which won't peel off from glass...
If you have the equipment and knowledge, then making them by yourself should be the cheapest option.

Typical simple alternatives seem to be based on Pepper's ghost.
If you want something "more 3D" not requiring the user to stand in some specific position or use special glasses, you could check the 3D monitor patents. There have been several attempts. IIRC some of them even resemble your idea (stack of light-emitting sheets).

>>1116327

I'm still pretty curious to see what would happen

>>1116321

What is KCL/KVL?

>>1116521
Didn't even occur to me to check 3D TV patents. Thanks anon I'll give it a shot.

I actually use a kind of plastic to adhere the copper traces to the glass and then dissolve the plastic with baking soda in a similar way I dissolve the copper with ferrochloride which doesn't react with the plastic after it sets

>>1116504

what a nutty question. an LED requires about 10mA to light, so if the output voltage remained at 500K volts, and you were drawing 10mA from it, you'd require an input power of 5000W to maintain that current.
what would happen, if you tried it, would be that the output voltage would drop to nearly zero. if you wanna put an indicator LED, put it on the input side.

if you wanna test if an output voltage is really present, you can put a neon bulb close to the output wires (not touching), and you hold the opposite side of the bulb in your fingers. or safer than using yr fingers, connect it to a grounded point.
another way is to see if the output wires can bend a thin stream of water flowing close to 1 wire.
another way is to use your nose, if you smell deadly ozone gas, you know it's working. (make sure someone is close-by to call an ambulance.)

>>1116631
It's a nutty question because I haven't really got a clue what I am doing.

I know electric goes in one end and comes out the other, and that 400kv sounds pretty high. (400,000 volts? I don't fucking know).

I was wanting the led to be on the output side to show when the coil is in use, there is already an indicator for the input, but I think that is a bit beyond me at the moment.

John ward is a pretty good source.

More aimed at electricians than electronics though.

>>1116662
https://www.youtube.com/watch?v=Wq0uODypaGI

why is bigclivedotcom not on the youtuber list?

he is fabulous and knows his shit

What is the difference between electronics and electrical engineering?

Hey dudes, I have zero fucking knowledge of electronics.
A few questions for some project I was planning to start.
I am gonna be unable to upgrade past my note 3 for a few years, so I wanted to buy a few spare batteries and make a little wallet for them.
What's the best way to ensure the longevity of my batteries? From my understanding it was that you're supposed to get it to drain all the way down to 0% then charge it all the way back to 100% at least once a month? Or is that not the case? If your battery has an unreachable sector at the bottom couple percent of its capacity from not doing this can doing discharge ->charge cycles help get access to these sectors again?

Hello guys, I am currently working on a small project and I would need a custom PCB board. I already have the design but I'm just looking for a manufacturer for 1, maybe 2, boards. It's really basic and I would like the cheapest deal possible, it just a 100x100mm one sided PCB.

What would be my best options? Contacting an online shop (I'm in Europe if it helps)? Rather use a breadboard (buy it might be really messy)? Thanks!

>>1116758

the phenomena you're describing only applies to nicad and nimh batteries. if you have a lipo, which pretty much every cell phone has, you dont have to worry about it. in fact, cycling a lipo will reduce its lifetime.

>>1116743

it's a retarded question. just read a dictionary. one is a thing, the other is a profession who works on the thing.


>>1116769

https://oshpark.com/

>>1116773
Thanks! I wasn't expecting an answer that quick. I will look into it.

I did a course on instrumentation controls last semester and I'm thinking about getting a microcontroller board to simulate a sort of DAQ.
I'm trying to decide between the Arduino UNO/Nano/Zero or Raspii 2 (maybe 3) to mess around with. Some of the projects I'm thinking about doing are simple motion sensing triggering a light/buzzer, spring loading a pot to act as a trigger switch, capacitive touch switching, step motor and servo control. Might even combine them all together for some pseudo-mechatronics.
From reviews, raspii seems "smarter" in that it can perform more calculations and comparisons as compared to the arduino. I might be wrong, I'm looking for a second opinion really.

>>1116773
Oh, cool, thanks, that's great to know. So I can just keep topping it off when it drops to 60% without any bad effects? my goal is to have a huge-ass battery in my backpack, then a couple spares charged up for the times when I know I'll be away from an outlet for a while.

>>1116829
>man kills himself in attempted backpack bombing

>>1116519
Side cutters like those are good, and they are worth splurging on. Still, get some cheap ones too to keep around for jobs you don't want to risk ruining a good one. You can both strip and cut wire with those, but keep the good pair for just copper, leave steel and anything else for the disposable pair.

>>1116837
I said note 3, not note 7

>>1116813

why don't you just circumvent the tarduino and get a real microcontroller with an actual DAC built in

also raspberry pi is way faster, and it runs a real OS but it takes more power

>>1116813
I have been messing around with my ras pi making a gameboy, switches and shit can be easily connected to the gpio pins, I am not sure what ardunio has in the way of that kind of stuff.

There will probably be more documentation for the ras pi than ardunio if you need that kind of stuff.

Is there such a thing as a gas discharge tube that won't be destroyed by 400kv?

I need a contained spark gap.

>>1116634
Like he said, put the LED on the input side. If you already have one on the input side, you don't need one on the output. Wire it so that the input LED isn't lit up unless power is flowing through the step-up module. You don't need to make sure power is coming out the other side, because it won't go in unless it can also come out.

>>1116694
Some people don't like him because they think he shills his channel in these threads. I have no idea if he does or not, just that I've seen people accuse him of it.

>>1116813
>From reviews, raspii seems "smarter" in that it can perform more calculations and comparisons as compared to the arduino. I might be wrong, I'm looking for a second opinion really.
A Raspberry Pi a fully functional computer, with a CPU around as powerful as something from the Pentium 2 or 3 era, and graphics similar to an Xbox. Arduino is babies first microcontroller, on a board with all the connections you need to just plug it in and go.

>>1116930
>I've seen people accuse him of it

I've seen 'someone' namefagging as him on here often.
Just putting the name out there is 'advertising'

Why are embedded displays so expensive?

Pic related is $50.

>>1117034
>Why are embedded displays so expensive?

you'd think capitalists (who are willing to mass slaughter others for using a different economic system) would understand the most basic precepts of their own system.
https://en.wikipedia.org/wiki/Fixed_cost

>>1116539
> What is KCL/KVL?
KCL = Kirchhoff's current law (the sum of currents into a node is zero).
KVL = Kirchhoff's voltage law (the sum of voltages around a loop is zero).

These are the mechanism by which arbitrary impedance networks are analysed.

>>1116838
Which brand is worth splurging on? I'll get a dedicated wire stripper, no sense half-assing it.

>>1117034
Buy those on ebay, its way cheaper and they have just about every display you can think of.

>>1117039
you lost, Bernie.

>>1117039
>he voted for Bernie

>>1115120
i broke the fire button on my vape the other day, pic related

>fires when i connect point 2 to either points 3 or 4
>connecting 3 to 4 does nothing
>connecting 1 to anything does nothing
>point 1 and 2 had some weird connection between them when i initially got it apart

right now my plan is to solder a button between 2 and 4, only because 4 looks easier to solder on than 3. is it possible that id need to solder both 3 and 4 to one side of the switch? bottom right of pic is what the original switch looked like, i've never seen them before

>>1116930
>>1116937
are you serious?

you people are fucking retarded

>>1117185
See how pins one and two have tracks coming away from them?

See how pins 3 and 4 are not connected to anything?

>>1117039
>who are willing to mass slaughter others for using a different economic system
You're thinking of communists, anon, communists do that.

>>1117201
not really
i'd guess you're trying to tell me 3 and 4 are negative and 1 and 2 are positive though, in which case id ask why 1 does nothing. unless its just supposed to be totally connected to 2

>>1115530
Does anyone know if the butane soldering iron is worth it?

It seems like a cool idea, but is it practical?

>>1117185
>i broke the fire button on my vape the other day
Good.

>>1116813
Just remember Raspi doesn't have analog I/O's onboard, but the arduino does. So if you want to use a lot of things like light sensors, you will need an ADC (MCP3008 is popular).

I like arduino personally, especially for motor control. Its cheaper and simpler.

>>1117204
No, I am trying to tell you the connection is between one and two, when they are bridged by the button being pressed it completes the circuit. Buttons sometimes have 4 pins, two pairs that are connected that are bridged when the button is pressed.

>>1117225
but if i connect a wire to 1 and 2 nothing happens, wheras if i connect a wire from either 2 to 3 or 2 to 4 it fires

>>1117227

the other dude is wrong. 3 and 4 are in fact connected to something - they're joined together and both grounded. so, the answer is to solder a switch between 2 and either 3 or 4 (makes no difference since they're joined by a copper pad anyway)

>>1117203
>You're thinking of communists, anon, communists do that.

right, coz 3 million dead Vietnamese dont count.

so what circuit sim stuff do YOU use personally? anyone use anything not in the OP?

>>1116352
Except its gas, so you cant get the temp right

>>1116085
Ive used stained glass copper tape to make circuits on glass before, works very well, you just have to solder the joints

>>1116850
Dont listen to this guy, rpi is not faster than arduino. Just running an OS slows the thing down dramatically

>>1117314
>Just running an OS slows the thing down dramatically

it can seem that way, but it's not true. once you're running a program in a RasPi -- meaning, a real program you compiled, not some interpreted script -- then you're accessing like 99% of the power of a CPU which is like 50,000 times more powerful than an Arduino.

>>1117346

oops, 50 times not 50,000 times.

>>1117286
let me add to this: which circuit sim software is the most simple to use? I would rather have a drag and drop software

>>1117206
>is it practical?
It's useful for repairing something 'in the field' where power isn't available.
For regular use it isn't practical because of the fuel consumed and inability to easily regulate the temperature to a stable, consistent temp.
I have one and seldom use it for these reasons but when I really need it I'm glad it's there.

I also have a ni-cad powered similar to pic related which is really handy for just a couple of quick connections

For regular use I have a 40 year old Weller solder station.

Hello guys, I have this circuit (pic related).
The output of the op-amp is supposed to switch to 5v when the voltage of in+ is higher than in-.
It works when I simulate it, but I built it on a breadboard and the output switches to 5v before in+ even reaches the level of in- and switches to 0v again after in+ surpasses in-.
What am I doing wrong?
I included my measurements.

>>1117380
I'm not too sure what you're trying to do (power-on delay?), but that diode thing won't work with LM324. The bias current of the inputs flows towards ground and since your diode blocks that current, the voltage at inverting input isn't what you're expecting.
Add a resistor from the inverting input to ground.

>>1117034
does that come with mutli-colored displays?

>>1117314

the raspberry pi is miles ahead of the arduino in terms of speed

Just look at clock speed, architecture (arm vs. 8 bit AVR), and power consumption to get an idea

>>1117418
>resistor from the inverting input to ground.
I added a 1k resistor but it didn't help. However I replaced the diode with a pot and it works now. Thank you.

>>1117438
Oh, right. The input voltage should be at least 1.5V below the supply voltage.

So EARLIER ON in this thread I learned an important lesson, that you can't just hook LED's up to 12V willy nilly, and that you need something to regulate the current.
NOW, I was wondering if the same applies to LED strips?
It actually looks like there's a resistor for every single LED on the strip, so I was just wondering what's going on.
I've hooked them up to 12V before without desoldering going on, unlike when I hooked a raw 10W LED up to a 12V power supply, but I've noticed the strips can get pretty warm.

>>1117034

>$8 on amazon

>>1117645

The LED strips do have built in resistors.

>>1117646

/pol/ was a mistake

>>1117649
Thanks kind anon!

Anyone have any experience reflowing gpus

Say I wanted to make a cube of leds stuck together by their legs in a 5x5 cube and I want to power it form a 9 volt battery. How would I calculate the resistor I would need, should the leds be in series or parallel? If there a benefit to either?

>>1117753
You need to know the forward voltage and current of the LEDs to calculate that. If you say the colour I could take an educated guess.

Do you just want all the LEDs on at once or is the cube a matrix where they're individually controlled?

I'm having some trouble getting a stupid simple "circuit" working (if you could even call it that)
I'm literally just trying to connect an orange diode to a battery pack with an on/off switch. Basically I wired the diode up like so and it turned on and worked then I wrapped some electrical tape around the exposed parts of the leads (because I'm covering them in chrome tape for a bit of reflection) and it died. I've tried 10+ different diodes and I swapped out the battery pack for another new one and it's still giving me trouble. Most of the LEDs would either be really dim or they'd be bright and then flicker and dim down. Some of them smoked a bit and got hot. I need two of these and the first one I did worked fine, is it the LEDs? Or am I doing something wrong

>>1117796
Here's a pic of the first one working as intended with no problems

>>1117796
you need a 40-50 ohm resistor

what's happening is that you're burning up the leds

>>1117799
Makes sense, but then why'd the first one work fine? I did the exact same thing to that one

>>1117796
>trying to connect an orange diode to a battery pack with an on/off switch
>>1117645
>So EARLIER ON in this thread I learned an important lesson, that you can't just hook LED's up to 12V willy nilly and that you need something to regulate the current.
This still applies to three volts.
>>1117803
>why'd the first one work fine?
Didn't you say:>>1117796
>and it died.
It was just a little tougher - you still killed it.

>>1117814
no no, this one >>1117797 works fine. It doesn't heat up or dim even after being on for a while.
Where would I connect the resistors once I get my hands on em'? I'm a total noob at this.

>>1117821
Also where would I get said resistors? A quick google search reveals I don't know what I'm looking for.

>>1117267
>60 million dead at the hands of Mao via famine, purging, state sponsored mass murder
>Similar number dead in USSR by similar methods

en.wikipedia.org/wiki/Democide

Examples[edit]
Some examples of democide cited by Rummel include the Great Purges carried out by Joseph Stalin in the Soviet Union, the deaths from the colonial policy in the Congo Free State, and Mao Zedong's Great Leap Forward, which resulted in a famine killing millions of people. According to Rummel, these were not cases of genocide because those who were killed were not selected on the basis of their race, but were killed in large numbers as a result of government policies. Famine is classified by Rummel as democide if it fits the definition above.

>>1117821
>Where would I connect the resistors once I get my hands on em'? I'm a total noob at this.

Since you're a total noob I like to be the first to tell you about Google.
Just type: www.google.com in the address bar
Then type your question in the search bar that Google provides: how to connect an led to a battery
Then click on the [images] button: pic related

>>1117831

nice argument you got there: every evil act becomes justified on the grounds that we're not the first.

Sup /ohm/, cross posting from /ham/

I'm trying to resurrect a Bearcat DX-1000 multiband receiver. Originally I had no digital function (see >>1117816) but I have managed to get that sorted rather easily. As I mentioned, reseating chips will often resurrect glitchy gear, I suggest you roll this into your first steps of troubleshooting of old kit if you don't already. We now stand with full control panel function, but no audio out. I have established that the audio chain is working by throwing a signal generator onto the input of its TBA810 amp, no problems there. As stated, I can tune local AM broadcast stations, but see no movement on the signal meter.

Based on pic related, I should be nosing around in, and upstream of, the AGC sections, right? This is where the signal meter is fed, and presumably, if the AGC section was faulty/dead, the squelch block would be stuck in "mute" mode, thereby preventing the mode switch from passing signal from whichever RF section/band is currently selected, to the AF chain.. r-right?

I'ma need to look up how all these blocks works so I know what signals I should be looking for, but I am so far out of my depth here it hurts. I know next to nothing about RF stages of devices, not much more about analogue beyond class B amps and light/motor controllers. I'd prefer the fault was in the digital sections to be honest, TTL I can work with.

Thanks legends.

>>1117756
Pink leds, I want to be able to eventually connect them to some kind of circuit to make them pulse on and off (breathing)

>connect dildo controller to led
>it lights it
>more intense vibration = brighter led

If I use one that has patterns of pulsing for vibrations it should in theory pulse the led the same?

>>1117821
in series
LEDs need a current limiting resistor.
Look up the specs for the LED. You need the forward voltage drop and forward max current

For example:
Vforward = 2V
Iforward = 20ma

If you're using 3V (2 AA batteries), then the resistor needs to drop the extra volt.
The current will be the same through both the resisror and LED.

Using ohms law,
R = V/I = 1V/20mA = 1/0.02 = 50 ohms
round up to nearest available value like 56 ohms

TL;DR:
Resistor Value = (V_applied - V_led_forward) / I_led_forward

>>1117945
I think I understand. So in theory an LED with the top specs would work with the resistors below? I'll probably order them later today when I get home.

>>1117646
That display appears to be malfunctioning.

>>1118026
Yes, it seems to be dropping the 'Literally'

Hey /ohm/, I have a couple of crystal oscillators lying around, and the code written on them is "EA1970 2.000 9948K". How can I tell what value (frequency) these are? I'm guessing they are either 2.000 kHz or 2.000 MHz.

>>1118041

the lowest freq crystal you're ever likely to come across is 32,768Hz. so it's 2Mhz.

>>1116850
>get a real microcontroller with an actual DAC
Such as? I don't want to spend much on them and I can get an arduino kit for cheap.

>>1116935
>>1116851
>I am not sure what ardunio has in the way of that kind of stuff
It does as well, but I'm not sure if I really need the extra features/power of the raspii.

>>1117214
>Its cheaper and simpler.
One reason why I'm leaning more to getting the arduino. What projects have you done with the arduino? I wanted to mess around with some servos and step motors.

>>1117908
They're probably 3v 20mA. Use this to design your array: http://led.linear1.org/led.wiz

>>1118169

microcontrollers with dacs aren't even special anymore

the arduino is just getting old

you can get a board/programmer for one for sure for cheap, not sure about which

Fished out an original Xbox while going through storage, I believe it was fitted with that updated power adapter that doesn't catch on fire when Microsoft did a recall. Labelling on the console says "220-240V 1.2a 50Hz" but only have compatible power cables that are 250V 2.5a.

Can I use these ones without issue?

>>1118188
yes

>>1118192
cheers lad

>>1118169
For learning purposes, you can't go wrong with arduino. I've mostly used it for motor control and for a whole bunch of sensors, like light sensors, ultrasonic (distance) sensors, infrared, microphones, all kinds of stuff! Although I've really only scratched the surface of its capabilities myself. I've seen people develop MIDI controllers and synthesizers using it.

Here is a fun project I did as part of a course on digital electronics at a local community college. One of the best courses I've ever taken, really.

The goal here was to create a digitally controlled gate crossing. I used three IR sensor pairs as kind of trip wires. When Thomas the tank engine passes the first sensor pair, the gate (servo) goes down, then when the last train car passes through the final sensor pair, the gate goes back up. Red and green traffic lights also change.

The middle sensor pair is supposed to detect whether an object (like a fallen tree) is blocking the crossing. If your interested I could send you the whole report lol.

As far as the programming goes, I just worked through an app called "learn C++" over the course of about a week, and found that I had all the skills I needed!

And here is one more arduino project. This one is a heart beat monitor with a digital display. The sensor here is TCRT 1000. And yes, the little heart on the LCD does blink.

It didn't exactly reach clinically viable levels of accuracy but it wasn't bad.

If I have a Variac and I plug in a bridge rectifier and add some high voltage caps after it I should end up with a high voltage adjustable DC power supply right? Any special concerns or considerations I should take when attempting this?

>>1118306
If you use a bridge rectifier, you can't connect the output "ground" to any other ground. If you do, something breaks or at least you blow a fuse.
The outputs (both, including the ground) are live. If you touch either of them and real ground, you'll get shocked.
These problems can be solved by using a half-wave rectifier. However, if you do that, it is critical that you connect the plug the correct way and that the wall socket is wired correctly. Otherwise you'll have similar problems than with the full wave rectifier.

A proper way to avoid these problems is to have an isolation transformer between the mains and the Variac.

>>1117185
ok so i accidentally got solder all over the thing that says R35 (this whole thing is really really small) but the chip still seems to work, what is that thing / should i just throw it away at this point?

>>1118358
o forgot to mention when i was trying to get the solder off of it the entire thing fell off

>>1118358
>R35
>>1118359
>fell off

I wouldn't worry about it. The factory probably had lots of extra R35s and was just trying to get rid of them.
Why else would they go to the trouble and expense of designing the circuit and installing them.

Do those "battery protection circuit" boards actually work? Can I connect three li-ion batteries in series on one of them and charge them with a single 12v psu?

>>1118355
> These problems can be solved by using a half-wave rectifier.
Don't do this unless the current drawn is trivial (specifically, below the transformer's saturation current).

The current drawn by a half-wave rectifier has a substantial DC component which will tend to drive the transformer core into saturation. Saturation results in the transformer behaving like an air-cored inductor, which doesn't offer much impedance and will draw significant current from the mains, burning out the winding.

>>1118358

dont throw it away. as long as the thing works fine, you dont have to worry about it, but it if starts to act fucky, then you need to put it back, or replace it with a full-size resistor. that means, you need to let someone with a multimeter and skillz replace it for you.

>>1118437
A normal transformer is closest to saturation when there's no load and if you use a half-wave rectifier and a capacitor, you can draw around one third of the transformer's rated current. This is limited by heating. Afaik Variacs aren't different in this respect.

www.hammondmfg.com/pdf/5c007.pdf

The real issue is the very iffy electrical safety, if there's no isolation transformer.

>>1118415
I have no knowledge of that particular board but there is a board similar to that in every laptop battery I've ever opened. (quite a few)
If the board is functioning properly it monitors each cell individually and controls the charge to that cell.

Buy one.
Connect it to three matched cells.
Charge and discharge then recharge the cells
Monitor/measure the voltage of each cell.
If they are the same, it's working properly.

>>1118415

It depends, some protection boards will have no balancing whatsoever. They simply disconnect the pack when it's over discharged or the discharge current is too high.

Some protection boards have balance logic, they disconnect the pack on overcharge, then discharge the overcharged batteries, then resume charging. Rinse repeat.

That's not proper balance charging though. You're better off just putting a balance charge port in the device and connecting a proper balance charger.

PS. you don't charge batteries with a constant voltage power supply, you charge it with a current limited power supply.

>>1118415

AFAICS the 8254aa has no logic to automatically balance cells during charging.

Here's an example of one which does :

http://www.ebay.com/itm/16A-Battery-BMS-Protection-Board-w-Balance-3-4-5-Packs-Li-ion-lithium-Battery-/181722717760

As I said though, need to use a constant current to charge.

>>1117848
You're right, but that doesn't make your accusation any less hypocritical. You sound ignorant if you attempt to take the moral high-ground by accusing someone else's (economic) ideology of doing what your (economic) ideology has done far more of. At least you've gained some mental illness victim points to spend the next time you stop by your local university safe-space.

>>1118827
>doing what your (economic) ideology has done

you're a dumb-ass for assuming that if you criticize one ideology it automatically means you support another one you've chosen at random for them.

supply-and-demand is the basis of capitalism, yet ask around and you see 99% of people cant explain what it is. my simple point was: people are willing to kill to defend an idea they dont even understand.

>>1118827
>doing what your (economic) ideology has done

you're a dumb-ass for assuming that if you criticize one ideology it automatically means you support another one you've chosen at random for them.

supply-and-demand is the basis of capitalism, yet ask around and you see 99% of people cant explain what it is. my simple point was: people who are willing to kill to defend an idea they dont even understand are stupid.

you remind of Judge Judy: make up your mind first, then invent facts to fit the conclusion.

>>1118827
>doing what your (economic) ideology has done

you're a dumb-ass for assuming that if you critique one ideology it means you support another one you've chosen at random for them.

the Law of Supply and Demand is the very basis of capitalism, yet ask around and you see 99% of people cant explain what it is. my simple point was: people who are willing to kill to defend an idea they dont even understand are stupid.

you remind of Judge Judy: make up your mind first, then invent facts to fit the conclusion.

>>1118249
That's pretty cool, most we ever did was create a logic circuit for a stoplight.
Could you put your code in a pastebin? I know the arduino is limited in memory, so I wanted to see how you handled each sensor.

>>1118254
I'm interested in this as well, do you have a schematic for it? And what was the pot for?
Do you think it would be more accurate if you went with a different sensor?

anyone know if such software exists in which you draw a schematic and you get a output/input voltage symbolic transfer function?

i have to analyze a single-amplifier biquad BP filter and it's MESSY AS FUCK and i haven't a clue if i got it right

>1119063

sounds like you want a circuit simulator. there are a few, some of which are free, the rest of which are piratable.
http://www.eetimes.com/document.asp?doc_id=1326778

>>1119063

sounds like you want a circuit simulator. there are a few, some of which are free, the rest of which are piratable.
http://www.eetimes.com/document.asp?doc_id=1326778

>>1118868
My point was to say that murder isn't unique to any ideology, as your (potential) hypocrisy implied. A criticism of capitalism typically puts you in the grounds of socialism, unless you're an anarchist criticising the actual laws that uphold capitalism or some other anti-ideology. I'm sorry for lumping you in with Bernie.

You were assuming that embedded displays actually were expensive and using this to assert your own potentially biased views of capitalism, instead of doing research. This sounds like making up your mind first then inventing facts to fit the conclusion to me. So, what is better than capitalism, ideal or otherwise?

Reminder Eagle is garbage and should be uninstalled.

https://youtu.be/0U8he-5Bqtw

>>1119063
>biquad
>messy

Git gud

But LTSpice

Retard here

I tried to fix my own headphone cable because a couple of parts of it were exposed and I kept getting shocked.

I already finished the job but my soldering skills suck.

>watch youtube videos on soldering for beginners and stuff
>need to tin iron and wires
>can't tin wires for shit
>can't do the technique to transfer heat instead of direct enamel contact
>hands are shaky
>don't have helping hands

please help

>>1119286
also, is there anything that can cover solid wires for insulation?

my superlux headphone has an exposed solid wire (headband) area that I want to cover. Electrical tape doesn't seem to stick permanently

>>1119286
You need something to hold your work, even a bulky bench vice. Secondly, your solder better be flux core, because otherwise you're gonna have a tough time. A tub of soldering flux is a hassle to use, and the shit gets everywhere. Lead free solder is shit, get the toxic stuff. Plenty of light and a bit of fume extraction are a good idea, but not compulsory. If you're rocking a tiddly <30W iron, you'll probably need to upgrade, but same goes for a >80W iron, those will burn the shit out of your insulation if you don't have some sort of temp/power control, assuming you didn't splurge on a soldering station. Helping hands are (probably) great, but I just cut some sharp zigzags and drilled some small holes in a piece of galvanised iron and jam the wire in them to hold and that works well enough for wire-to-wire work, though I can't recommend this solution.

I know what you mean with headphone cables, I just fixed mine a few weeks ago and it was a pain in the arse. The individual wires were in a flat cable which was a pain to strip the insulation off, and they were too thin to have any luck soldering strongly. My entire 3.5mm jack end was messing up so I spliced on one of my spares, and put heatshrink tubing on to tie them together. Heatshrink tubing is a godsend and it's permanent, but you have to be able to get it on the wire in the first place. You can buy fusing silicone electrical tape, but it will cost you $20. Getting the wires the same length and isolating them was a pain. Even once I finished, the mic wouldn't work and I'd already shrunk on the tubing (its a TRRS headset). What kind of voltages are you dealing with that you shock yourself through your headphones?

>>1119300

Heatshrink.

>>1119302
>What kind of voltages are you dealing with that you shock yourself through your headphones?
Not what I meant, the cable is pretty long and sometimes when I jostle in my room it (exposed wiring) hits my legs or arms.

Funny thing is that I kept messing up the size of the shrink wrap I bought but in the end it was ok.

Pic related is what I did. I'll post the finished cable with shrink wrap on the next post.

>>1119308
and after I individually used electrical tape for the wires and then shrink wrap

>>1119303
can't insert it unless I take apart the whole thing.

pic related is the part where the solid wire connector is exposed

What are good circuit books, other than the Art of Electronics, that teach applications?

Every book seems to have a lot of analysis and basics such as small signal model, op amps, power converters. I already know the basics from all the circuit classes im taking and have taken.

I want books that will give me intuition on how to design circuits. I would like a book that is very specific and in depth.

Can anyone give information on this? It's the oven of a Pax 2. There's a four wire ribbon cable that is supposed to attach to it somewhere, but it snapped off. I'm guessing the orange thing is some sort of temperature sensor, which explains the two smaller traces of the ribbon cable, and the big thing wrapping around it is the heating element. Any ideas where the leads are on the heating element or sensor?

I also can provide pics of other parts of the pax if anyone is interested. It's pretty well broken down right now.

>>1119570
> very specific
Books like AoE are rare and the only semi-decent alternative I can think of is the ARRL handbook. Usually such books cover only one application, like audio amplifiers, rf amplifiers, or power supplies. So, better decide the general topic first.

Then there are books which list plenty of different circuits (Elektor has published several), but explain their operation only in pretty general level.

first time posting here.

I tried fixing my washer for what I believed was a lid switch dying.
I put the 16 gage wire in the first and 3rd slot (as every single guide showed) to make the continuous loop, and even confirmed with the wire thickness that those 2 spots were the main current and the middle was the ground.

As soon as I plugged it it, it POPPED hard, blew the fuse, and now the 3rd spot (and on the 16gage itself) is black around the tips.

Im not even sure how it did this. Both sockets still work and nothing was touching after what I did. I was under the assumption that nothing like this would happen so long as it never touched ground (like when you hook up only the reds on jumper cables between cars. Nothing sparks until theres a ground connected).

Did I somehow do something wrong?

>>1119579
Yeah I guess when I mean very specific, I mean a single application type of deal.

What good books are there that are like this audio amplifiers?

How can I make a driver for a stepper motor?

I have a bunch of ULN2003's, 74hc595's, NPN transistors and n-channel mosfets, also 4 wire (which I think are bipolar) and 5 wire stepper motors (which I believe is monopolar). Can I simply switch each coil sequentially with a mosfet for each one of them and power everything with 12v (maintaining a common ground with the controller) PSU?

>>1119587
Can't say I'm that familiar with audio, but Audio power amplifier design handbook by D. Self is rather well-known.
If you're ok with decades old stuff, you should check what transistor makers like Motorola and Mullard have written. Avoid stuff old enough to have germanium transistors, though.

>>1119588
>How can I make a driver for a stepper motor? I have a bunch of ULN2003's

googling ''ULN2003 stepper motor driver'' returns 225 trillion results.

>>1119605
B-b-b-ut.

How do I know how long I need to power the coils in order for the motor to actually turn?

What if I want to use discrete n-mosfets?

Is it possible to drive the bipolar steppers using only n-channel mosfets and npn transistors (like what is inside the uln2003)?

Can anyone point me towards some good aftermarket cable sleeves to provide extra insulation against ambient heat and wear?

>>1119588

Alright, so I took off the back plate on the unipolar stepper I had and you wouldn't believe what was beneath it. I redid the solder joints as well as I could. Now, how do I know if the coils are still good? Do I just measure their resistance with a multimeter?

>>1119608
> Is it possible to drive the bipolar steppers using only n-channel mosfets and npn transistors (like what is inside the uln2003)?
Yes. Use H-bridges.

>>1119660
Don't I need pnp transistors to make a h-bridge?

>>1117185
what the fuck is this braindead-monkey-tier soldering

>>1119308
>>1119309
Nigga those wires are going to short and probably kill your headphones. Heatshrink each splice seperately, then heatshrink the whole thing.

How would i go about making a LED matrix that has pic related shape ? it needs to be at least 32x32 grid (as in, be 32 LEDs wide and 32 high) and around 20cm2.
i found out that if i make it myself, i'll need to solder 847 RGB LED by myself and honestly, i never soldered anything on that scale yet, and it would be a waste of LEDs because i'd probably fuck everything up.
however, i have found a premade matrix on adafruit (https://www.adafruit.com/products/1484)) but now the problem is that it's not shaped like i want, and i'm not sure i'd be able to just desolder every excess LED on that board without any further problem. i thought about LED strips, but i have no idea about how to control each individual LED with them.

any ideas , /diy/ ?

>>1119701
Use individually-addressable RGB LEDs, get a circuit board fabricated, and use solder paste and a heat gun to install the components.

>>1119704
A heat gun will blow the LED's away, I'd rather try using an electric skillet or oven

>>1119712
Only if you're retarded and/or use a tiny-ass tip.

>>1119716

A skillet will reflow everything at once with no risk of blowing anything away

I think I'll replace the ULN2003 with individual mosfets. 12v / 6.8 ohm per coil gives about 1.8a and the ULN2003 can drive at most 500 ma per channel.

>>1119725

I decided not to replace the ULN2003 with 4 mosfets with an inverting driver circuit. The bjt base will be driven low by the outputs of the 595 shift register.

Can I add pull up resistors to the 595 outputs to keep the stepper motor from spinning or burning its own coils when the 595 outputs are floating?

>>1119735
>decided to replace

Fix'd. I'm not going to use the uln2003.

What do you guys think of this unipolar stepper motor driver? Would it work, or would it explode?

>>1119582
>Did I somehow do something wrong?

Yes.
You posted a picture of an animated feature character instead of schematic or photo related to your question.

>fixing my washer
not even a brand much less, a model number
>put the wire in the first and third slot
slots of what?

Try again with photos or at least drawing of what you're asking about.
It's also helpful if you state your country since wiring codes and practices differ by region.

>>1118987
Hey, if you're still there, here is the code for the train project. Probably not the most elegant, but it worked. And I did cheat a little by using the servo.h library (I do know better now though lol).

http://pastebin.com/8ujDrPU8

As for the heart rate sensor, there are definitely better IR sensors out there. I've seen ones that even come in a sort of silicone finger-clamp or sleeve.

Real O2 saturation devices typically use multiple wavelengths of light, and the transmitter and receiver are on opposite ends of the finger. I'll see what I can dig up on that project. I believe the pot was actually just there to adjust the contrast of the LCD screen.

>>1119695
I did cover them with electrical tape separately and then covered up with heatshrink

has anyone ever made a board with proteus?

it seems user friendly enough, though the only other layout software i've used is eaglecad.
and that was only once for a simple board


I'm wondering because I'm worried about complying to limiting specs of board services and such.
I'm thinking dirtypcbs, oshpark is more expensive and I dont live in america.

what do i need to look out for? I dont want to get my files rejected or get fucked up boards.

>>1119817
>what do i need to look out for?

Just the design rule file the manufacturers usually provide for you

>>1119815
I can't buy heatshrink smaller than 4mm>1mm at my local Jaycar, I don't know if it even exists. The electrical tape will insulate the wires fine inside the heatshrink as the tight (and possibly glue-lined) rubber will hold the tape in place, but the electrical tape is nowhere near as rigid so be careful you don't bend the soldered joints too much before you've shrunk the tubing. That's probably what happened to my mic cable, I'm an idiot for not checking if it worked before shrinking on the tubing.

>>1119923
I will remember that anon. thanks!

kinda wanted to use shrink wrap but then I'd have to cut and expose more of the cable.

>>1119817

Proteus let me short out a 5V and Ground on the schematic because I was lazy and didn't bother learning how to use the Design Rules Manager. Worth looking into. The websites should have some specs that you have to keep in mind, like how small a trace can be or how close sutff can be to each other. Be careful not to get confused with mils meaning thousands of an inch and regular millimeters. I remember advanced circuits having some sort of free software where you could input your gerber files and it would show you what it got interpreted as and if it broke any of the specs for them.

I think it was this one: http://www.4pcb.com/free-pcb-file-check/index.html

I thought there would be some manufacturer errors and shit but all the mistakes on the board were due to me.

>>1117368
>>1117206
I had a butane torch with a solder attachment, and the filling needle thing shit itself, so when I went to refill the butane would just spray out.

I found what's MUCH MUCH more useful, is the USB soldering irons. Although it might say 8 (but is actually 6) watts, they can solder a ton of shit. I use it more often than my normal soldering irons because it heats up quick, cools down quick, and I'm not fucking around with the cord (finding an outlet or pulling on stuff if I plug it in a desktop power strip and move)

Big clive has a great video:
https://www.youtube.com/watch?v=o-8D5t6TJYU

Mine I got off ebay iirc and the sensor thing didn't work, so it would randomly go on and off, mostly off. Pissed me right off. I found by random touching the board that shorting one of the 555 pins to high (not sure which pin, might even have been ground) that it would turn on or turn off when I decided. I had some tiny switches and screws, so I literally put a switch in mine. If you wanted to be a real bastard about it, put the switch in-line, and then just completely short the 5V to the gate of the mosfet or whatever it uses.

I power mine from a generic 2.1A portable usb battery and it works fantastic. Rarely it goes out (I think the supply has a standby) but I just unplug and plug it back in and it usually starts right up.

I use a copper-plated wool scrubber to wipe off the tip but I've used paper towels or toilet paper. What's nice is because it heats up in like 10-15s at most, even if I shut it off and let it cool, I can just turn it back on to melt the solder at the tip. I use "expired" lead-free solder and it works great. I've used it to desolder some stuff to, if you let it sit for a little longer before using it (like 40s) it gets stupidly hot and can go through bigger blobs fast.

If the tip ever went I would look for tips, probably not find any, and just buy a new one cause it was like $7 free slow shipping or $10 for faster shipping.

>>1119666
No, but you do need a high-side driver (i.e. the ability to drive the base/gate above the collector/drain voltage). Particularly for a FET (a BJT can probably tolerate 0.7V of Vce if the current isn't too high).

Typically you use a charge pump driven from the output to provide the high-side voltage.

anyone recommend a good starters book, currently looking at this one

https://www.amazon.com/gp/product/B00MHFWUPO/ref=as_li_tl?ie=UTF8&tag=marketorder-20&camp=1789&creative=9325&linkCode=as2&creativeASIN=B00MHFWUPO&linkId=77a21971591f36d7e714e363043a3bb3

>>1120061

the recommended books for electronics are in the first post of this thread. the book you mention is about electricity, which is generally about 120Vac stuff, and is very different from electronics. if you wanna be a hobbyist, then electronics is what you want. electricity is more about getting a job. a lousy dirty job at that.

I'm going to wire five computer fans to a 12v 4.16a power brick for cooling in a custom eGPU case.

Regardless of overkill, is there a simple way to wire a knob of some sort between the supply and the fans to decrease power so that the fans aren't on full blast so that I don't have to get a fan controller and a molex to ac adapter?

>>1120070
I'm very new to electronics and this is basically my first project (apart from earlier wiring an old cpu fan to a 12v ac adapter).

I've found a couple projects online using a rheostat for each individual fan, but I'd like to have one knob to control all of the fans in unison. I did remember I have an old potentiometer from a guitar project I never completed years ago but it is rated for 500k Ohms. Is this doable?

>>1120070

if you want simple, you can get one of these and put it in series with the fans. it's inefficient, but who cares, electricity is cheap.

of course, a PWM controller is the gold standard for this application.

>>1120082
I basically already have the fans coming and decided upon my current solution after ordering them and while full steam is okay, I'd prefer some sort of control. The fans are all 3 pin. I do have a potentiometer I was going to use for a guitar project that never got completed that is rated for 500k Ohms. Could it handle all of the power coming through when turned down? I'm super new to electronics and kind of fumbling my way through it right now.

>>1120084

a pot from a guitar will produce a wisp of smoke and die within 5 seconds. they're usually rate 1/10 of a watt, whereas you need about 30W (very roughly).

>>1120085
Thank you! I did not know that and could not find any wattage rating. I'll find a local electronics store and see what I can dig up.

>>1120085
Couldn't find any information on the sale page but on the site I finally found the amps. Each fan only runs from .84-2.04 watts so around 10w total for the fans. Though because the power supply I'm using will provide ~50w, do I need a rheostat rated for that?

>>1120091

if you dont care about looks, you can use light some old light-bulbs as series resistors. a 120V 50W halogen bulb for example is about 15 ohms. you can use more than 1 in series or parallel to get more or less resistance.

>>1120093

that works out to approx 1A of current max, so if you used a pot to drop half the voltage, you'd need a pot rated 12 ohms at 6W (realistically you'd use a 10W or more to keep it from boiling)

>>1119773
I built this and it kind of works. The stepper can spin both clockwise and anti-clockwise. Adding a pull-up resistor to the OE pin worked well enough to prevent the motor from spinning when that pin is disconnected.

It gets pretty hot. Is it normal?

I'm having a hard time finding those female breakaway pin headers on Digikey. I assume some of you have bought them before. Could you give me the part number for them?

Can anyone tell me what will happen if I leave pin 12, VL, floating on this analog switch?

http://www.vishay.com/docs/70040/70040.pdf

I can't find much information about it in the datasheet. I'm hoping it'll default to the logic levels given under the truth table on page 1.

I got a pack of "miniatures 1-amp diodes" from radioshack. Does that mean the diodes will be OK as long as they aren't subjected to current greater than 1 amp? I don't want to blow them up on my little LED circuit.

>>1119588
>4 wire (which I think are bipolar) and 5 wire stepper motors (which I believe is monopolar)

if i understand correctly, the bipolar will need two H-bridges as the both need to be drive one way, then the other during sequence.
the 5 wire one just has a common lead, so you can connect that high and pull the 4 wires down in sequence.
uln's are excellent for this.

>>1120214

they probably have an upper voltage limit too

>>1120189
If you leave it open, you can expect that the IC won't work. It is supposed to be connected to your logic supply, typically 5V.
That said, there are versions of DG211 which do work without VL.

>>1120269
Thanks.

>>1120180
http://www.ebay.co.uk/itm/10pcs-40pin-Strip-Tin-PCB-Female-IC-Breakable-Single-Row-Round-Header-Socket-SK-/381576373379?hash=item58d7b96483:g:~xwAAOxyhS9TfWBY

can i use a normal ac dimmer on a 12 volt motor?

>>1120614
>ac dimmer
is it an ac motor?

>>1120614
a dimmer is a triac.
google it and you'll see what it does.

>>1120614
>can i use a normal ac dimmer on a 12 volt motor?

nope. you might be able to get it to do simple on/off but you'd need at least 30V to get thru the diac, before it reaches the triac.

4u

Any obvious problems that stand out here to you guys? This is my computer speaker, which keeps shutting itself off randomly and occasionally turns itself back on for a second, then back off. Doesn't usually work for longer than a few seconds, but occasionally will work for more than a minute.

I don't really see any bulging capacitors or anything very suspicious. I thought the one cap near the fuse was the culprit for a moment, but it appears to just be hot glue on the top of it. I've replaced capacitors and fuses before, but really don't have any kind of expertise with this stuff. I powered it on while it was half-disassembled like this and couldn't see anything happening when it would power itself off. There are no strange smells and I haven't seen smoke at all.

There's also an on/off knob with an LED on the front of the speaker, which adjusts the volume too. It's in the bottom image. Should I try to take that part out too to check for issues?

Any advice or opinions would be greatly appreciated!

>>1120931

90% sure it's a connector

a PC speaker amp really has no reason to fail

>>1120931
I think I see a relay on the back edge in the top picture. Those are usually the first parts to go because of worn out springs and contacts.

>>1120931
theres orange gunk all around the area by one end of the fuse

at first I thought it was adhesive, but maybe not beacuse it even looks like there's some on the corner of the relay in the top pic

check that and check loose connections

>>1120084
Since they're DC fans, you can use a PWM. Anything over a few hundreds 100hz cycle speed wouldn't cause any problems. I could link a circuit I made, I first butchered a normal 555 circuit somehow, and after "fixing" it ends up letting me do 0-100% speed by using a 0-100% of VCC signal. Only takes a 555, two resistors, two caps, and a mosfet. It might take less because I just have those on my board and I was using it in combination with something else. The PWM is mostly linear, but the frequency changes. The minimum frequency was above 1khz I think on a 5V supply. I used a logic-level mosfet as the "switch" on the PWM output (there's a 1.7ish volt drop on the output, but a logic level mosfet will let like 8 amps through at that level)

I actually made a really clever design, because it runs into some stupid issues if you can't properly sink current at the control voltage pin.

>>1120931
>on/off knob with an LED on the front of the speaker, which adjusts the volume too

Yes this is a prime suspect.

Op amp, negative feedback: why does the left circuit work but the right doesn't? In real life you would tie +Vsupply to the positive terminal and -Vsupply to ground, no?

>>1121040
Opamps need negative supply voltage to produce negative output voltage. Typically they also need negative supply voltage to be able to handle negative input voltages.

The primary nuisance with single supply operation is moving "ground" away from zero volts.

>>1121040
Think about an Opamp as two opposite polarity transistors, one of which amplifies the negatives, one of which amplifies the positives. You can't amplify a negative voltage of say -0.2V up to -1V without a negative source at less than -1V, all voltages comparative to ground/earth. You've tied the ground to the negative power source, so now the greatest negative voltage the opamp can amplify to is 0.
E V E R Y T H I N G I S R E L A T I V E

>>1121048
>>1121059
Right, I think I follow. How does that work in practice? In a battery powered circuit for instance, surely you wouldn't need two separate batteries to supply power to the op amp? What I also don't understand about the circuit on the left is how the positive terminal of a -5v supply is different from the negative terminal of a +5v supply.

I have trouble waking up in the morning and want to make a wearable device that will give me an electric shock at a set time. How difficult would this be to make considering I have 0 knowledge and how to get started?

>>1121064
No offence but you shouldn't be working with opamps if you don't know whats the difference.

The difference is that in the right circuit you tied the negative rail of the supply to ground (the triangle) so it is now 0. The voltage between the positive and negative supply rails of the opamp is 5V. On the other hand in the left circuit you had two supplies, V2 which produced +5V relative to ground and V3 which produced -5V relative to ground. The voltage between the supply rails is thus +5-(-5)=10V. I hope you can see those are pretty different scenarios.

In real battery powered applications you would utilise biasing in a similar way to biasing transistors but I doubt you know how that works. So for example if you have single supply battery powered op amp (0 to 5V) and you want to amplify a 0.1V amplitude sine wave that oscillates between -0.1V and +0.1V, what you need is to bias the sine wave and center it on 2.5V. Then it will oscillate between +2.4V and +2.6V, which is in the workable range for the op amp. The way it is done is using DC blocking capacitors and voltage dividers and making the negative feedback only work for AC (another capacitor).

>>1121068
dog collar
connect controller to timer

What is the point of the capacitors in this circuit, especially on the LEDs? The Arduino makes the LEDs light up sequentially, the resistors drop the voltage for the LED, but what's the 10uF cap for? The OUT line is also just a PWM output

>>1121070

>>1121064
Give pic related a go for any simple circuits. I think you can use a voltage regulator IC to make the ground instead if you want, I've never used one though. I learnt about it by making Make's Elektrosluch: http://makezine.com/projects/weekend-project-sample-weird-sounds-electromagnetic-fields/

>>1121069
>>1121079
Thanks for making me slightly less stupid.

>>1121069
By the way, I meant I didn't get why in the left diagram V3 was made -5v and flipped upside down to produce the negative voltage on the + terminal, rather than have it be 5v and tying the + terminal to ground. Seems confusing to me. I see it makes no difference though, so I assume it must be convention.

>>1121089
The voltage source in LTSpice will always provide the nominal voltage on the positive rail relative to the negative rail. So it doesn't matter if you make the nominal voltage -5V and tie the negative to ground, or +5V and tie the positive to ground.

>>1121089
You can do it both ways. I guess whoever drew the schematic just thought that calling it a -5V supply would be clearer. It's not a convention.

can anyone help me with vaping electronics?

currently using Petri Lite v2 and it works. Problem is that the firing button is heating up. I did some reading and it either could be resistance build up or the entire thing needs cleaning.

So I cleaned the entire thing and even sanded it down to get a more clean connection. It still turns hot to the touch. I've searched for solutions but I am a retard and I can't properly diagnose what the problem is.

Friend says it is either that the spring isn't conductive enough to transfer the current. but I am not sure of what steps to take.

pic related is a 5-year old diagram I made. the positive pin is always in contact and the negative pin (button) needs to be pushed to get a connection that runs through the body from the firing pin.

>>1121071

the capacitors create a fade-in fade-out effect similar to the ''knight rider'' circuit.

>>1121096

you're carrying a bomb in your hand, and you're worried about a little heat from the switch? if anything, the heat is good, it means there's some added resistance in the circuit which means less current, which slightly less danger of an exploding battery.

>>1120931

i once fixed that exact same speaker. one of the two 1000uF caps at the top LHS was bad, and gave me no sound on the left speaker. however, your problem seems to be the big amplifier chip connected to the heatsink. i'd get the datasheet, and probe two points using a different computer speaker: check if there's an audio signal going into the chip (actually 2 signals, L and R) and then check if the signals are exiting the chip.

if the amp chip is bad, consider replacing all the circuitry with a cheap class-D amp from amazon.

>>1121107
nvm fixed it. faulty spring that was producing resistance because it wasn't fully connected flush to the pin.

>>1121096

it means the vape is probably shitty

seems like it would be wise to use one that uses a transistor to drive the coil

>>1121123
ill be buying a new variable mod soon I guess.

Anyone comfortable with Assembly for 8051 based microcontrollers here?
I want to toy around with an at89s4051.
Now from school I remember something about jumping to the Adress 0x100h being the first thing to do but I can't recall why.
Anyone know why one would do this? In school we used a xc888 by the way.

>>1121145
There's an interrupt vector table at the beginning of the memory. How much you need to jump to get over it depends on the exact chip you're using (and what interrupts you enable, if you want to save all rom you can).

>>1119973
>buy a usb soildering iron
Cmon bro. Dont make idiots buy useless shit

>>1121157
Is pic related what you are talking about?
If yes would jumping to 0034h + highest instruction length always work?

>>1121168
If you want an actual handler for each interrupt, then you'd typically have an AJMP at 33h and your main program would start from 35h. Or from 36h, if you used LJMP.
The minimum which would count as a handler would be a single IRET, in which case your main code would start from 34h.

I have a Sony TA V3 amplifier (pic related), my neighbor gave it to me a couple of years ago because he didn't need it anymore and I've been using it ever since because it works fine enough.
Recently the right speaker has started to crackle a little bit at high volumes, and the base seems a little less powerful compared to the left speaker.
I know old amplifiers often need replacements from time to time, and this one must be at least 30 years old, but I don't know where to start. Can anybody point me in the right direction?

I opened it up some months ago to clean the dust and replaced the bulbs of the display by LEDs (with the appropriate current limiting resistor) because bulbs were dim and one had blown, I haven't made any other changes or repairs to it.
I have basic experience with analog electronics and know about amplifier theory (currently studying EE), I also have all the tools I need to fix it (o-scope, multimeter, soldering iron, desoldering pen....)

>>1121096
Not familiar with that mod but the switch looks like the nemesis
I'd guess resistance buildup.
The spring doesn't carry the current, the pin it's over does.
Remove the nut and clean the pin and the hole it goes through.
Don't sand it, it'll make the fit looser.

The switch on my nemesis wears and gets sloppy(or comes from china that way)
I get a brass screw from the local hardware store, put it in a drill, and file it down to replace the tiny pin that acts like a keyway to get a tighter fit.
Requires a bit of patience to get a good fit but the resistance and heat will go down and the button will bind less if pushed from the edge.

I've heard graphite will help, but I've tried it and can't say if it helped or not.

On a side note, putting a washer made from a cereal box under the pin that screws in will reduce travel & make it fire easier and bind less.

>>1121177
>I'd guess resistance buildup.
>The spring doesn't carry the current, the pin it's over does.
>Remove the nut and clean the pin and the hole it goes through.
>Don't sand it, it'll make the fit looser.
already did that! took some time to actually fit a new spring.

>On a side note, putting a washer made from a cereal box under the pin that screws in will reduce travel & make it fire easier and bind less.
got pics?

>>1121171
This makes sense. Thanks.

>>1121181
>got pics?
I think this is thinner than a cereal box. Probably made from junk mail.

You can see the "pin that acts like a keyway " on the left button. If yours has that, making a tighter fitting one will help.

>>1120157
Ok, since I basically can't find cheap/free unipolar stepper motors I'm going to attempt to build a bipolar stepper motor driver.

I think I can make a bipolar driver with two FETs (for low side switching) and two DPDT relays working as h-bridges.

maybe not the right place to ask this, but does anyone know anything about wireless signal boosters? like if I have a piece of equipment that broadcasts a wireless signal 80m at 433mHz , is there something I could buy which would amplify that signal to give it a larger range?

>>1121321

>>1121321

>>1121331
>>1121334
thanks! I meant to ask if they will work as intended. Like what i'm buying is a station which has 3 sensors which all broadcast at 433MHz. If i signal boost the sensors, will the station accept the boosted signal or would it cause some issue?

what do i call those connector things on the power supply and where do i buy them?

>>1121358

Banana jacks/plugs. Any electronics place that sells connectors is sure to have some. Some RC hobby shops have them, too, if you're willing to pay their premium.

4mm is the de-facto standard size. They make others, but they're so uncommonly used that I've never even seen anything else in person.

>>1121359
i dont suppose you know what banana jack is in arabic

>>1121360
not him but can't you search banana jack in the latin alphabet on arabic amazon or something and see what comes up?

>>1121362
i think ill have better luck looking up apple daniels

I want to learn more about vacuum tube technology. I decided to look at an archive of this board to see if anyone else has asked about this topic, and I have found several suggestions that I plan on reading. One of these suggestions was getting an RCA tube manual to familiarize the reader with several concepts regarding the way that tubes work.

Does it matter what edition of the manual I get? Should I just get the most recent one I can (which I think is 1975)?

>>1121365
Can you just buy them on a place like aliexpress or something?
https://www.aliexpress.com/item/i/32581965140.html

How would I build an impulse oscillator?

I thought about just starting with a simple square wave oscillator like a schmitt trigger oscillator or 555 timer and just putting the output through a differentiator but the issue with that is I get two impulses corresponding to the rising and falling edges of the square wave. I only want the impulse from the rising edge.

Googling impulse oscillator gave me nothing, maybe there's some other name for it I just don't know or something.

>>1121449
Basic tube tech has been known since the '20s/'30s. How deep do you want to go?

>>1121505
>>1121505
I'm just starting out to be honest. I'm mostly interested in how they are used in audio applications. I want to just learn about common tubes in these circuits.

Anyone here fix cell phones or similar electronics? I replaced the screen on my ipod 4 touch and the adhesive that came in the kit keeps peeling apart. Is there an adhesive I can use in it's place?

>>1121546
3m adhesive strips between 1&3 mm are often used for this.

can i use an audio amp as a 2.4 ghz radio amp.

>>1121488

if you use a CMOS differentiator, then you just add a diode to kill off either the positive or negative peaks. (ignore the bottom part of the circuit - just use the top part. you can use a Schmidt inverter instead of the AND gate)

>>1121636

on this planet, audio amps go up to 20Khz - maybe 100Khz.

>>1121636
>10hz to 0.02mhz circuit
>Use it for 2400mhz
>ggwp

>>1121488
Depends on your idea of impulse. For example, a 555 oscillator with low duty cycle might be good enough.
Relaxation oscillators built from antique things like PUTs and UJTs produce narrow pulses natively. You can build similar oscillators with SCRs, neon bulbs and other components too.
Blocking oscillator might do the job as well.

And if you want to go with your current setup, you could just add a diode to the output to get the positive going pulse. Or if you use the output to drive a transistor, it does the diode's job too.

>>1121662
>>1121686
how do i make a 2.4ghz amp then ?

>>1121896

Buy one, or take enough EE courses or self study to the point you can design microwave electronics. Might take a couple of months or a couple of years.

>>1121908
definitely years senpai

>>1121174
Prime suspects: electrolytic caps, potentiometers, solder joints on high power components (like output transistors).

>>1121522
Personally I feel that BJTs and FETs are easier to understand, and have more modern learning material. Once you have some idea of what a transistor does, it's easy to see how tubes are a variation of the same thing.

>>1121908
>>1122022
To be fair, you don't need to know much to design a working low power 2.4GHz amp.

>>1121331
>>1121334
>millihertz

i'm taking a shot at a custom dc dc converter and i want to be able to throw cap values in easily for the control loop. will shitty ceramic bead cap leads fit snugly in machined pins? i don't have any on hand.

>>1122033

why the capacitor right before ground?

>>1122433
works with the inductor to short rf that would otherwise get onto the power rail and make your circuit a shitty antenna

rate my soldering abortion.
11 shift registers standing on the side for 88 outputs.

will later be used to drive a 14x60 "dots" vacuum flourescent display, after some level shifting

>>1121192
thanks!

got any tips for tight threads? I also keep getting micro metal shavings when I screw them back on and off when replacing my batteries.

>>1122560

I approve the VFD project.

>>1122560
It's a complete abomination

Electronics newbie here. I have this problem I've been battling for some time.
I need to make a fuse of sorts that would basically monitor several DC inputs, and whenever any of them exceeded maximum set voltage, say 12V, it would shut it down and inform a controller. Then it should be possible to re-enable the input with a command.
So far I decided to use a PIC microcontroller that would monitor the voltage but I ran into problems with the number of sources as most seem to only handle one input. Is there a controller more suited for this kind of application or should I take completely different approach to this problem?

>>1123022

I don't know anything about the PIC you are using, but in most micros you have a multiplexer (mux) inside that basically wires the ADC to a physical pin

It may have 1 ADC, but that just means it can only read 1 voltage at one time. The pin it reads off of can change.

you can probably switch the pins that the ADC is connected to through some bit flipping in whatever register the mux uses. Look in your datasheet for this.

>>1123049
Interesting idea but doesn't that essentially mean that it will be cycling through the inputs? That is not very optimal. Guess I will have to look for another controller.
Or wouldn't it be possible to implement the actual input switching with some analog components (transistors?) and have the controller handle only the 'logging'? What I'm trying to do is basically adding the logging and remote reset capability to a fuse setup.
Sorry if it sounds stupid, I'm only now getting into real-world applications.

>>1123088

The analog components you speak of are inside of the micro already

Any solution that involves multiplexing the ADC with outside hardware is pointless because it already does this on its own.

I wouldn't say that it's a bad idea to use a multiplexed ADC. It will still get many samples every second even as it is cycling through inputs. It depends on how fast you need to respond to your signal (I don't suspect it's that fast)

If you are determined to do it in analog, you should just skip the micro completely.

>>1123022
old school you would have an opamp configured as a comparator for each input. comparator feeds SR latch. latch drives a relay maybe through a transistor stage to control the source.

the set voltage would be configurable but only in hardware not in software.

then you can take a digital input from the latches to monitor individual circuits and a digital output to reset each latch.

if you run out of inputs what you do is use a parallel to serial shift register to read all the inputs with a single pin. same on the outputs if you want. monitor for state change by tying all of the latch outputs into a chain of OR gates to feed a single interrupt pin. when the pin changes and fires an interrupt you can scan the state of all the latches.
only problem is you won't be informed of a second trip but the circuit will still trip.

if you feed into ADC it will be muxed on the chip, i doubt you will find a chip with lots of adcs. microchip has product selectors have a look at how many adcs they have. problem is with adc you have dead time, the adc takes a sample then disconnects in order to measure the sample, if there is a transient overvoltage it won't be noticed. problem is worse with a mux, the dead time increases with each input being measured.

how many inputs do you need, how fast do they need to trip etc.

Anyone have any experience etching RF PCBs? The PCB I'm making has GHz components and there doesn't seem to be a good way to impedence match PCB traces. Best I've seen is to add a small nF ceramic cap on the output of all my surface mount components but that doesn't seem right since the inpedence will change depending on the length of the trace. Could I possibly etch two traces side by side and create a coax effect using their capacitance?

>>1123109

> there doesn't seem to be a good way to impedence match PCB traces

Huh? You can put 50 Ohm impedance microstrip on any PCB.

>>1123162

On any multilayered PCB I should say.

If push comes to shove you can use coplanar waveguide on a single sided PCB though.

Does anyone know what this is? I'm new to electronics, and i'm trying to fix my walkman. This was the only suspicious looking component. It says BPMB6A SE g. Thank you.

>>1123198
That's some polivariable capacitor
http://www.datasheetarchive.co.uk/bpmb6a-datasheet.html

>>1123198
That's some poly variable capacitor
http://www.datasheetarchive.co.uk/bpmb6a-datasheet.html

Sup /diy/

I am a caver and often find myself mapping out caves. I had an idea that maybe I could make some sort of device that could use sonar or lidar to generate a map of the cave. Sort of like how ocean scientists using sonar to map the ocean floor. Was wonder if you guys may have any ideas on how to go about doing this.

I'm an electrical engineering graduate student studying antenna theory/ design atm so I've got pretty solid theoretical knowledge, just not sure how I would go about actually making something like this.

I have an arduino uno and a raspberry pi 2. I'm leaning more towards sonar because it'd be more compact (I think at least) and less fragile.

Current idea is to use arduino/processing as that would be very easy to make a GUI and plots and everything. I would like to use the raspberry pi though since it is a bit stronger.

Any ideas?

>>1123221
Thanks man

>>1123239

A LIDAR scanner with accelerometers and a ton of software could do it. How much manyears and money do you want to spend a year R&D'ing it?

I don't think you have enough knowledge yet. Worrying about low cost processing platforms when the LIDAR alone is a very expensive bit of kit is a bit silly to begin with. This PHD level research.

It's been done by the way :

http://www.3dlasermapping.com/zeb1/

There might be more, but that was the first thing which turned up for handheld lidar environment scanner.

Currently working on a tiny USB controller for kshootmania/sound voltex. Atmega32u4 for MCU, Sanwa buttons, rotary encoders, and neopixel rgb LEDs for button backlighting. Planning on sandwiching it between a bunch of laser cut acrylic layers.

I'm using pcbmodE, which gives a lot of freedom for design (all done in Inkscape). I'm hoping to come up with some neat designs on the front/back using all the layers (silk/gold plated pads/soldermask), but don't know what I'll do yet. Any ideas?

>>1123277

sounds masturbatory

>>1123283
more or less. I've never finished a project I've started so I figured I'd pick something doable and at least make it sexy

kind of a complicated question but giving it a shot here anyway. I bought a chinese LCD controller to operate a salvaged LCD with a rasberry pi. I received it but after troubleshooting for a while I observed that the wire payout on the LVDS cable was different than the layout on the LCD datasheet. I messaged the guy to get a properly wired replacement but dont feel like waiting weeks.

Long story short, has anyone here ever made their own LVDS cable? Its just a bunch of really tiny wires curled together.

Howdy my dudes. I am trying to replace the broken power port on a laptop but I am failing to desolder the old port off.
I tried using a desoldering pump but I could not get the tip in between the finnicky gaps so a lot of solder remained.
I tried using desoldering braid, it worked great on the first socket but it removes barely any solder on the other 3 that are left.
I tried looking at guides and everything but as far as I can tell I am doing everything right. Except that I don't have extra flux to put on the braid as I work like one of them suggested (the shop was out of flux). Any newb mistakes that I might be doing without realising?

I only have a shoddy soldering iron with two settings, 30watt and 60watt. Which setting should I be using for a mobo? I have been using 60watt to get the solder to melt quickly but I am worried about burning the board.

Please help.

>>1123409
The pin you are working on needs a little solder around it to 'wet' when you start the de-soldering.
If it's completely free of solder on the top of the board around the pin the heat can't transfer easily.
Add a little bit of solder to the area you want to work on. Then apply the wick and heat with the iron.
Once it starts going into the wick keep working on that pin until the wick stops picking up solder.

There is always risk of de-lamination no matter which iron wattage/temp you use.

Low wattage/temp makes the work go slower - more time required raises risk.
Higher wattage/temp work goes quickly but the higher temp raises risk.

The wattage of the iron should be based on the physical size/area of the item being soldered or de-soldered.

I have 50 Watt heater clothing that I want to power from 16,4 V battery pack and I want to be able to control switching it on and off with arduino pro mini - using its 3.3V digital pin to open and close transistor.
What kind of transistor model do I need for this? It should withstand at least 3 Amps of current without overheating.
There are like milions of transistor types and I cannot find exactly what I need...

>>1123540

>>1123540
I'm not too down on what the specs of a NPN BJT mean, but you can just pop on over to Digikey and filter by all those characteristics and find one that you can buy locally/order in low quantities. You might even find a free sample you can request. You might want to look for a FET instead of a BJT, but I wouldn't know.

Does anyone know if you can ignore one of the inouts on a logic gate. Like if I have a nand gate with 4 inputs and i only need 3, could i not use one of them?

>>1123941
Unless you want it to never turn off. Vcc should be ~5v, jump that to the input you wont use.

This potentiometer is fucked and i dont know what kind of new one to buy. How fucked am i?

>>1123957
Ow shit i actually found it

Kind of related to electronics:
I am building a laser out of an old dvd burner
I need to buy some glasses before I light it up but I'm not sure what ones to get

It's a red laser which means it's wavelength is around 630nm

What color glasses?
I've looked on amazon but all the glasses are ambiguous about what they protect against

>>1116256
Op is not going to have access to wire binding machinery if not he would be done it already

>>1116539
No, he is telling you you're modelling the wrong thing. The tree structure is caused by capacitive discharge and not by mere conduction alone.

>>1123941
If it's a NAND/AND tie the unwanted input to high, if it's a NOR/OR tie the unwanted input to low, and if it's a XOR/XNOR what the fuck does a >2 input XOR gate even mean? If it's a NOT gate you're retarded.

Just bought a mobile electric heater similar to this to chill out outside, but it's always blasting at full power ( 3 positions switch: off, 1 lamp on, 2 lamps on ).
I would like to add some kind of variator on the electric cord so both lamps are always on but I can dim the power. What kind of regulator should I get ?

I built a 3kw electric scooter, I built all the motor controller and electronics myself, what is the best way to make a mechanical on/off switch on a 70V 150A vbus?

How does this look like? Powered with molex and will control psu fan.

>>1124378

automotive battery disconnect switch

It will be rated at 12/24 volt and several hundred amperes.
It's listed for that because that's it's intended purpose but should handle 70v easily.

>>1124387
These are too big to be used as an ignition on the handlebars though.

>>1124414
High current relay with a 12 or 24 or 48 volt coil.
Tap battery supply at required voltage.
Small switch on handlebar to operate relay.

>>1124384

i aint even looking at your retarded plate-of-spaghetti schematic.

this pic shows what a schematic is supposed to look like. you can grok the whole thing in 5 seconds, coz you're not having to trace the path of each line. there are zero crossed lines. the values of the components are right next to the components, so your eyes dont have to wander back and forth.

Unknown sylvania tube
Markings read
ac aea
9 pins
Heater is on pin 4 and 5
Help

Unknown 9 pin sylvania tube
Heater on pins 4 and 5
Markings are ac aea
Please help identify

>>1124693
>>1124688
Didn't mean to double post

>>1124695
u can delet 1

>>1124701
Eh

>>1124688
>>1124693

all tubes look the same to me

>>1124693
>Markings are ac aea

9 pin tubes like that 'usually' have a number first for the filament voltage
followed by a couple of letters then another number

12AX7, 6BQ5, etc
other markets used IDs like CV10321, N709 7189, 7189A, E84L, EL84S
these were all alpha-numeric or just numeric
I've never seen just letters

are we gonna have a new thread?

>>1124364
Normal dimmers are triacs. I wouldn't imagine it would cause trouble.

>>1123540
"logic level" or "powertrench". FDB6035AL Is one, I think it permits around 15A at room temperature at 3V