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/diy/ - Do-It-Yourself

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1600531 No.1600531 [Reply] [Original] [archived.moe]

New Old Stock Thread: >>1594926

0. Electrics ≠ electronics. Home appliances/sparkies to /qtddtot/ or /sqt/. PC assembly to >>>/g/.
1. Do your own homework. Search web first. Re-read all documentation/datasheets related to your components/circuits. THEN ask.
2. Pics > 1000 words. Post relevant schematic/picture/sketch/9001.5 hours in MS Paint with all part numbers/values/etc. when asking for help. Focus/lighting counts.
3. Read posts fully. Solve more problems than you create.
4. /ohm/ is an anonymous, non-smoking general.

>I'm new to electronics, where to get started?
It is an art/science of applying principles to requirements. Find problem, learn principles, design and verify solution, build, test, post results, repeat

>Project ideas:

>Principles (by increasing skill level):
Mims III, Getting Started in Electronics
Platt, Make: Electronics
Geier, How to Diagnose & Fix Everything Electronic
Kybett & Boysen, All New Electronics Self-Teaching Guide
Scherz & Monk, Practical Electronics for Inventors
Horowitz and Hill, The Art of Electronics

>Design/verification tools:
NI Multisim
iCircuit for Macs
KiCAD (pcb layout software, v5+ recommended)

Mouser, Digi-Key, Arrow, Newark, LCSC (global)
RS Components (Europe)
eBay/AliExpress sellers, especially good for component assortments/sample kits (caveat emptor)
Local independent electronics distributors

>Related YouTube channels:

>Li+/LiPo batteries
Read this exemplary resource first: https://www.robotshop.com/media/files/pdf/hyperion-g5-50c-3s-1100mah-lipo-battery-User-Guide.pdf
>I have junk, what do?
Take it to the recycler.

>> No.1600534

I don't like having to wait for my soldering iron to heat up for a few quick joints. Battery-powered irons have caught my eye.

Bigclive gives big ups to https://iso-tip.com and it seems pretty alright. I'll probably wind up getting one to support small business.

However, I also always see these cordless soldering irons in Harbor Freight. https://www.harborfreight.com/3-in-1-cordless-soldering-iron-64034.html
Have any of you used the harbor freight one?

>> No.1600535

Get/diy a solder station with T12 tips.
The heating element is integrated in the tip there, which allows it to heat up in just a few seconds.

The TS100 and TS80 also use similar tips which also heat up very quickly.

>> No.1600537
File: 205 KB, 1200x1200, 64034_W3.jpg [View same] [iqdb] [saucenao] [google] [report]

haha what the fuck

>> No.1600541
File: 66 KB, 800x508, 3_solder_joints.jpg [View same] [iqdb] [saucenao] [google] [report]

fast enough?

>> No.1600549

what does this go with?

>> No.1600562


>> No.1600581

>no K-tip

>> No.1600910
File: 270 KB, 1033x1461, 1525070542916.png [View same] [iqdb] [saucenao] [google] [report]

this thread's digits brought to you in part by the slow but venerable TLP531 optoisolator

>> No.1600921
File: 2.96 MB, 4032x3024, B528509E-807D-42F2-866B-DC32BCA1C871.jpg [View same] [iqdb] [saucenao] [google] [report]

>Lithium Chemistry
Jesus christ I hate vapefags but most of the 18650 blogs are from those cunts. Bro says ICR is one of the most dangerous types of cells and can’t be discharged >1C. Is this true? How the hell would that work in a power tool battery pack?

Thought I saved pic of black dude holding the metal part like a pen.

>> No.1600934

Does flux feel like magic to anyone else? I've been building electronics for 15 years and I know how and why flux works, but it just feels like black magic the way it makes solder go exactly where you need it in the perfect amounts.

>> No.1600937

I think the magic feeling comes from how it coats parts, cleans, and transfers heat so effectively.

>> No.1600940

any sufficiently advanced technology is indistinguishable from magic

>> No.1600944

power supplies are the new glue logic. discuss

>> No.1600945

It's literally made of tree sap too(rosin flux atleast), like what the hell.

>> No.1600956
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halp, the flux fume dissolved my brain
and no calculator allowed

>> No.1600958
File: 23 KB, 848x349, 1541666156679.png [View same] [iqdb] [saucenao] [google] [report]

do you agree that Pic related is the same circuit?

>> No.1600968

Lithium Ions have datasheets too, they should say a continuous and pulsed maximum current on them. No clue what kind of current a power tool pulls in use, but at startup I know it can be much higher. Perhaps the diy electric vehicle crowd would be slightly better equipped to answer your questions, as their battery duties are more varied than just powering PTC heating elements.

>> No.1600969

yes, I do, thanks. i had a dose of acetylcholine to neutralise the flux effect and now i'm on track again. 12 parallel 4 is 3 and 8 plus 3 is 11. now we have 11 parallel 5 which is 55/16, hmm..

>> No.1600972

i think i solved it. 64/16 would be 4 and 48/16 is 3, so it must be in between which means (B) is right.

>> No.1600977
File: 10 KB, 306x298, inside 18650.jpg [View same] [iqdb] [saucenao] [google] [report]

The battery-powered spot welders know best.

>> No.1600979

For pulsed loads perhaps.

>> No.1601013

I use ts100 and i absolutely love it.
If you can supply it with 24V it heats up in less than 10 seconds to 300°C

>> No.1601074
File: 41 KB, 505x575, atvground.png [View same] [iqdb] [saucenao] [google] [report]

What is this symbol at the bottom.
Its the ground side of a battery, it gets grounded to somewhere put theres another wire coming off to a connector and i don't have a clue what the little T thingy is. they decided to not say what their symbols mean it he book.

>> No.1601084

ok, noob here. I just made a 50Mhz LC oscillator that runs on 9V. Now I want to use that signal to mess around with simple digital modulation.
What sort of amplifier should I use for this? I just need something near 8Vp-p and that doesn't fuck with the oscilator when connected.
Is making a common emitter amplifier like in the textbooks enough for this frequency?

>> No.1601087
File: 15 KB, 584x441, Untitled.png [View same] [iqdb] [saucenao] [google] [report]

You can improve cheap optocouplers speed with a pnp transistor. It makes the Vce more constant and that helps with the miller capacitance. Managed to get from 1us rise time to 200ns once.

>> No.1601098

Diode. there should be a part list if its an actual schematic.

>> No.1601112

for least effect on the oscillator, take your output from the output of the gain element, maybe even use a FET amp stage
anyway before you put the wave on your antenna you need to clean your signal, the last thing you want is for all the tire pressure alarms on your block to go bonkers. an LC low-pass is enough. you might want to pick up some RF toroid cores and lern2wind
into what? into the conventional 50 ohm load, that's 1.28 watts, 31.1dBm, about 100mA static consumption with a class A amp and peaks of about double that. plan on dissipating half a watt through that transistor, which is a lot to ask of a 9V transistor battery. did I mention horrible linearity?
also you might want to think about a loicence if you transmit above 20dBm (which is more like 4.5Vp-p) or at all in the ham bands (you might be stepping in the 6m band right now). they hate freebanders and interferers and will track you down and report you like the bored, territorial, civic minded people they are. if you pull your oscillator just a few hundred kHz lower, you might be in a safe band generally used for low-tier radio-remote-control models/cars and such. since you're not sending voice, you're probably in the clear (check your local laws and regulations before you proceed)

that doesn't look like our flavor of diagram. you might want to check out a nerd site for that make of whatever it is
but I'm going to guess the three-lines symbol is frame ground and non-detachable, and the one-line symbol is some sort of ground bus for accessories etc.

>> No.1601116

Circuit doesn't work, no base drive for the NPN transistor and the 1K resistor would ruin the claimed effect. The natural solution is a common base stage, emitter directly connected to the (open) collector of the coupler and the base properly biased, cascode configuration.

>> No.1601117
File: 67 KB, 1000x1000, HTB1Pbzqo5OYBuNjSsD4q6zSkFXae[1].jpg [View same] [iqdb] [saucenao] [google] [report]

This doesn't have and fancy digital shit in it right?
It is just 5 slots connected in parallel to each other right?
(it's intended for phones i think)

>> No.1601118

I didn't pick any specific values for the resistors, they change with whatever current you set the coupler with. And it does work, I've built it.

>> No.1601119

I just want to trigger some LEDs and mottors using the oscilator, the range would probably be my living room.

>> No.1601122

there is an outside possibility that it might have a few analog bits if its supposed to act as a microfilter too or maybe some lightning protection or possibly even a ringing capacitor but no nothing digital if its for connecting extra phones.

>> No.1601138

do you think there will be any problems if i want to use it as a hub for i2c devices ? (+, -, sda, sdl)

>> No.1601143

that's a voltage-controlled current source inside the optocoupler

that is correct

if you turn the speed down, and don't have too long of stubs connected to that expander, and manage to get termination right, you might be okay

>> No.1601158

i run at 100k and need 2 meters at most for the connected devices so it should be fine

>> No.1601243 [DELETED] 
File: 130 KB, 1366x768, btR3C.png [View same] [iqdb] [saucenao] [google] [report]

I have a mini split air conditioner, and I want to modify it.
I want to stop indoor fan every time outdoor fan stops running, so I can leave it on 24/7, without worrying about fan consuming electricity.
AFAIK, they have BLDC motors.
It is on-off unit, so it has 5 wires going to outside unit (L-compressor, N, PE, 4-way valve, L-fan)

>> No.1601245

I have a mini split air conditioner, and I want to modify it.
I want to stop indoor fan every time outdoor fan stops running, so I can leave it on 24/7, without worrying about fan consuming electricity.
AFAIK, they have BLDC motors.
It is on-off unit, so it has 5 wires going to outside unit (L-compressor, N, PE, 4-way valve, L-fan)

>> No.1601260
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found a crack in the PCB near the hole, it causes the relay to not turn on properly. How do i fix this, can i scrape away to the copper and put a bit of solder across it?

>> No.1601272

scrape, pre-tin, wires.

>> No.1601276
File: 4 KB, 168x126, wires.jpg [View same] [iqdb] [saucenao] [google] [report]

like this

>> No.1601278

even for that tiny crack I need to wire across it? i have small gauge wire. what exactly is pre-tinning?

>> No.1601280
File: 86 KB, 789x731, wire.jpg [View same] [iqdb] [saucenao] [google] [report]

or do you mean bare wire? i was going to do this

>> No.1601283

What's that meme soldering station I should get if I am tired of $20 chinkshit and want to spend like on the order of $100? Hakko 880 or something, right?
Also, if I want to have a hot air thingy too for desoldering and shit - can I buy a blower handle for that same hakko station or should I get something else instead that has both?

>> No.1601291

>bare wire?

>> No.1601298

Better drill a hole on the end of crack, to relief tension, and do scrapy-scrapy to those traces, and solder tiny wire on top of it,

>> No.1601308

well even after fixing that, my problem didnt get fixed. but at least i avoided a future problem i guess

>> No.1601482

Can you figure out why it doesn't work? Perhaps the component that was causing the PCB stress in the first place is damaged also?

>> No.1601484
File: 421 KB, 2048x638, sa370.jpg [View same] [iqdb] [saucenao] [google] [report]

its an issue with the relay on this old stereo receiver. when i plug it in the relay will click-click-click like its not getting power, but if i let it sit pluggde in for a few hours it will click slower and slower until it just turns on like normal.

>> No.1601488

That sounds like an awful problem to troubleshoot. It sounds like it could be the driving transistor, the nearby passives, or the relay itself. Try measuring the current into the relay by measuring the voltage across what I hope will be a resistor in series with the coil or the base of the driving transistor, otherwise I'm turning up blank. A replacement relay with a lower driving current could be better use of your time, or even just a solid state alternative (FET with pulldown) since it's likely LVDC.

>> No.1601491
File: 2.51 MB, 3264x2448, IMG_3855.jpg [View same] [iqdb] [saucenao] [google] [report]

well what happened was that i ordered it on ebay and it was working before it shipped. fedex damaged the package severly, and I was able to file for a refund for damaged but I got to keep the unit. Again it DOES work normally eventually, its just if there's a power loss or a drop in AC voltage it will go back to its clicking cycle until it feels like working again. I didnt see any other cracks on the PCB when i looked though, but it could be an issue somewhere along the PSU lines.

>> No.1601500

>all those shielding traces

>> No.1601507

wish me luck on my calc II final
it's the only thing preventing me from getting into engineering college

>> No.1601513

Can you remember your laplacian identities?

>> No.1601529

this is accurate. i know all the textbook on designing a switcher, offline or dc-dc, and the thought of it still daunts me. easier just to buy one. and there's just no contest when you're not the one paying for it.

>> No.1601536
File: 137 KB, 1440x810, 51838811_1997472516973276_3619010632692531200_o.jpg [View same] [iqdb] [saucenao] [google] [report]

What is the output sink/source current of gate driver????

>> No.1601539

based sudaca

average current is Qg*f*Vg. peak depends on gate loop resistance but gets up to around 2A.

>> No.1601555

best nitty-gritty low-level books on RF signals over cables for amateurs? background in basic power theory, telecommunications, and some molecular physics from college
figured I'd ask here for better chances than /qtddtot/, thanks in advance or just tell me to kick rocks
need to learn how to into digital signals and return paths for work but know basically nothing outside of a little radio

>> No.1601561


130nC*20kHz*20V =0.052A

>> No.1601564

130nC*20kHz*620V(High side) =1.612A
do I understand it right?

>> No.1601565

Pretty sure it's the gate voltage that matters. Where are you getting 620V (in terms of your project) from anyhow?

>> No.1601566

no i was dumb that's actually power, 52mW. average gate current would just be Qg*f, for all the good that does you.

>> No.1601569

ิbootstrap gate driver
now i get it
the larger the gate current the faster gate will be charged and turn on

>> No.1601571

No I meant more what are you using as a 620V voltage source

>> No.1601572

yes. your dominant losses will always be conducting and switching (linear region) losses, which iirc should be balanced in your design to minimize losses. the whole gate system doesn't generally dissipate much power itself but just controls how long your fet takes to switch, aka how long it spends in the linear region.

>> No.1601573

just assume the maximum number from IR2113 datasheet

>> No.1601574

Oh, I thought it was implied that there was a ~620V rail. I wouldn't use the maximum voltage instead of the actual rail voltage in that sort of calculation.

>> No.1601593
File: 472 KB, 1497x1445, IMG_20190425_141136.jpg [View same] [iqdb] [saucenao] [google] [report]

Look at my baby, it just arrived and it is beautiful!

Please, try not to be too jealous.

>> No.1601594

put it in your ass

>> No.1601633

In also interested.

>> No.1601638

i have the 888d and i'd recommend it. buy other types of tips too.

i have an expensive hot air station and it's an annoying piece of shit so you'd might as well try the blower handle.

>> No.1601641

>so you'd might as well try the blower handle.
Is there one, even? I actually looked through hakko's website yesterday after posting this and didn't find one. I can see hot tweezers, a couple of different irons (including a nitrogen compatible one lole), but no blower.
Could you point me to one if you know of one?

>> No.1601642

I would like to use one of those cheap pcb making services.
Can i just send them a file in made in fritzing or is there some specific software you have to use?

>> No.1601643

I am also open to different apps for making pcbs.
My designs are pretty simple so i don't need anything fancy

>> No.1601645

>legit hakko
>on the order of $100
lmao no

>> No.1601647

Ew, use KiCAD (FOSS) or pirate Altium or Eagle, don't bother with that webshit. Proper PCB design software can be learnt in a day.

>> No.1601660

Fritzing is shit but what makes it "web"shit?

>> No.1601663

Nobody uses it so it's covered in cobwebs

>> No.1601666

I domn't mind pirating, which of them do you think is the best?
I want something that is extremely simple because, 90% of my designs are single layer pcbs with 20 holes and some traces in between

>> No.1601674

Oh you actually download it? That's even worse!

I've only used KiCAD and it's more than good enough for what I use it for. Eagle has a free trial that you could check out also.

>> No.1601681
File: 1.57 MB, 3648x2736, P1050104.jpg [View same] [iqdb] [saucenao] [google] [report]

hi /ohm/
so i salvaged this nice b&w crt tube out of a mini tv and want to power it to display lissajous curves on it
i understand that you need several differents voltages, at least 3 if i understand correctly, as :

some 6v for the heater
something like 135v for the electron gun
hv kv for the flyback

i've only found power supply for oscilloscope tube that don"t use flyback transformers, so what would be the simpliest way to power it ?
i have this shematic for the hv flyback http://www.electronics-lab.com/project/flyback-transformer-driver/ , would that work ?
thx !

>> No.1601700

>over cables
that would be transmission line theory, no?

oh I meant that most any function of significant complexity has its own power supply rail requirements, and these days it seems more common when integrating new functionality into a design to add a buck or even a linear regulator than a few odd logic gates
non-isolating converters don't bother me much anymore, what with just-add-water converter ICs and cookbook design. off-line converters are still a bit voodoo to me. I might try putting a couple together this summer just for the experience

why don't you look up the datasheet for that tube to see what it needs?

>> No.1601707

that's calc III and diffeq for me I believd

>> No.1601710

Is it normal for boost converter to make hornet sounds when you draw higher currents from it?

>> No.1601718

half a shot before a final's a good idea, right?

>> No.1601723

>Can i just send them a file in made in fritzing or is there some specific software you have to use?
It has to be a Gerber file. The software used to generate it doesn't matter.

>> No.1601729

Try doing some aerobic exercise and taking 200mg of caffeine 30 minutes before the test.

>> No.1601739

if it's chinese then that's normal. don't use it anywhere near its rated current.

>> No.1601741

what makes that sound tho? there is no speaker

>> No.1601743


>> No.1601747

the inductor is a speaker. some capacitors are also speakers, though not in this case. when you pass current through it, it generates a magnetic field that imparts a force on the inductor's core, causing it to vibrate (and compresses it i guess via magnetostriction, but i kind of doubt that's the driving factor). if it sounds at all like a hornet instead of tinnitus that means the converter is operating at very low frequencies which generally don't make sense from a design perspective, so it's either a piece of shit or its listed ratings are exaggerated or something's wrong with it. it'll work though. i guess the vibration might wear out the enamel on the inductor coil eventually which is a fire hazard.

>> No.1601776

Is it possible to shutdown a triac or a thyristor in the middle of the wave? I'm trying to make some sort of high power trailing-edge dimmer.

>> No.1601779

> if it sounds at all like a hornet instead of tinnitus that means the converter is operating at very low frequencies which generally don't make sense from a design perspective
Low-frequency vibrations usually correspond to the mechanical resonant frequency of the core or windings and/or the frequency response of the control loop, not the switching frequency.

>> No.1601787

>the frequency response of the control loop
if that's where's the driving energy at those lower frequencies is coming from then my mind is blown, since i can't think of any other source below the switching frequency

>> No.1601792
File: 45 KB, 764x450, 1527838232786.jpg [View same] [iqdb] [saucenao] [google] [report]

in photoflash circuits I have seen a second SCR which switches off the main SCR by discharging a negatively charged cap into it. you might be able to turn off a 3-quadrant triac the same way. search for "thyristor commutation" to learn more about how people do it
I have also seen people use SCRs/MOSFETs/IGBTs for ac switching by putting them inside a bridge rectifier and isolating the gate drive

it could also be overcurrent protection timeouts. lotsa magic in those little black boxes

>> No.1601796

That's what I need, thanks.

>> No.1601810
File: 71 KB, 902x623, elv-di300.jpg [View same] [iqdb] [saucenao] [google] [report]

Example of BR+MOSFET
230V 300W

>> No.1601815

I failed the final

>> No.1601817

why didn't you cheat? that's how i got through school and i haven't had any problems since.

>> No.1601819

You can't cheat good algebra skills
It also doesn't help I have a professor who sees herself as the gatekeeper of engineers, who also likes to put very esoteric and difficult problems on her exams.

>> No.1601820

i cheated at 90% of my exams
only an idiot wouldn't. 90% of what youa re forced to learn in school is useless trash you will never need

>> No.1601821

>that would be transmission line theory, no?
I reckon so, but you're asking the wrong guy, will google around and see what I can find, thanks for the term

>> No.1601822

>It also doesn't help I have a professor who sees herself as the gatekeeper of engineer
You say that like keeping out brainlets is a bad thing.

>> No.1601826

change schools immediately

>> No.1601835

how do you even cheat on a college exam? I'm not going to, it's not worth it, but I am considering buying a used TI-89 for the CAS system

>> No.1601892

in my favorite example, i had a guy turn around and hand me the answers literally five minutes before the exam. it's all about knowing people that can get you old test q/as, even if they're not exactly the same. i definitely wouldn't have passed that class otherwise since the prof was a senile old soviet.

>> No.1601943

It gets worse in college.
>t. depressed 7th semester EE

>> No.1601944

Also once in college get the fucking old tests, teacher can't change their personalities or their way of thinking for basic classes. Some other classes are so hard I had a guy leave to get a coffee because it was hard as shit.

>> No.1601952

I *am* in college.
Believe me I did everything I could to get the old tests. She refused stating that it would be pointless as she changes her exams every semester, and she does. There's no real way to prepare for the curveballs she throws on the test. You think you'll be prepared after having done every problem in the book but then she fucks around with trig sub, or some incredibly difficult partial fraction question that has extremely strange solutions that you practically need a matrix to solve, etc.
I could go on.
She tests you on how well you can solve her problems, not on how well you can apply what you learned in the course.

>> No.1601958

Sell your memes and get out.

>> No.1601970

That was the plan...
Until she failed me with a 69%

>> No.1601994
File: 44 KB, 606x530, rank1.png [View same] [iqdb] [saucenao] [google] [report]

That's how it is, there are bright bulbs and there are dim bulbs.

>> No.1602004
File: 62 KB, 606x530, 1533266657592.png [View same] [iqdb] [saucenao] [google] [report]

did I do it right?

>> No.1602012

Just do your best, in time you'll see that most of that is more of the same, and that the real thing they teach in those classes is dealing with cunts and stress, and it weeds out the weak.

>> No.1602029

It's you fuckers cheating all the time that pushes up the difficulty of the tests in order to keep the pass rate constant, go fuck yourself.

>> No.1602036


>> No.1602039
File: 4 KB, 700x250, mains protection noise circuit.gif [View same] [iqdb] [saucenao] [google] [report]

Found this while designing a similar circuit, and I found it a bit odd that the MOV(s) were going after the common-mode and normal-mode chokes. I'd have thought that putting it before the chokes to react as fast as possible would make more sense. Thoughts?

The project is a little mains/rectified mains box to tap into with binding posts. Using two single diode rectifiers because capacitance is cheap and I'd rather have the ground reference. By two rectifiers I mean one positive and one negative for a HV split rail.

B, A and E, C and D.

>> No.1602045

>I'd have thought that putting it before the chokes to react as fast as possible would make more sense. Thoughts?
i want you to explain what you think you mean by as fast as possible

>> No.1602051

Well the chokes will have some effect on the response time, since they'd resist changes in current, right? So you could have a >1kV voltage spike at the input before the MOV's voltage gets above its trigger level, and this higher voltage could breakdown between traces or between the common-mode choke.

>> No.1602053

my reasoning is that, like many conductive materials, lamp filaments have a positive temperature coefficient of resistance and behave as self-heating PTC thermistors. Ro||p = 1/2*Ro = 1/2*Rp, so B will bear the greatest voltage of any lamp and have the highest resistance, therefore dissipating the most power and producing the most light. A and E will dissipate equal power, but not as much as B, but each of them will be brighter than OP

>> No.1602054

I suspect he was disputing your labelling choice, since I've no fucking clue what you're trying to show just by changing C and D to O and P. Is that the stellar absolute magnitude scale?

>> No.1602055

oh shit I didn't read, sorry for being a retard

>> No.1602061

It says rank from brightest to dimmest, not indicate in a humerous manner which two bulbs are the dimmest and leave the other labels alone. clearly B is the brightest, the labels should have been reordered.
the other was that typical nomenclature op is poster who starts a thread, it seems strange to insult an innocent party arbitrarily.

>> No.1602062
File: 100 KB, 600x800, 1023309965.jpg [View same] [iqdb] [saucenao] [google] [report]

>Valve oscilloscope needs repair
>"Old valve oscilloscope. It used to work fine. Just plugged it in, green light on front goes but then noticed some smoke coming out of the back."
>$1 reserve
oh man, shame it's too far to be worth shipping

>> No.1602182

I have a year left what am I in for
I'm actually a computer engineering major but it's very similar to EE here

>> No.1602184

Eagle is super easy to use, has gotten a lot better the last few years. Free version would be more than enough for your needs.

>> No.1602243

stick with fritzing son, it is developed by the cern eggheads so it's guaranteed to be good
plus it has no rival for simple pcb design, and you can even switch between breadboard, pcb and schema design at any time, no other tool offers that and it is completely free too

>> No.1602248

Fritzing is garbage. Doesn't even have a proper editor for parts.

>> No.1602258

I need to charge a power drill liion accumulator with my bench power supply.

Since liions are sensitive cunts i need to adhere to proper charging cycles, so i was thinking of running the bench power through an SSR and the SSR will be controlled through a PWM from an arduino so i can easily set the exact current going into the liion while measuring the liion voltage with the same arduino.
will this work?

>just get a charging circuit from chinks
no those are for shit like aa cells, the currents i need would atomize them

>> No.1602263

fuck i just realized the minimum output voltage is 5v on the ssr
so i will change the ssr for an array of fets

>> No.1602274

Ok firstly, SSRs are only for switching AC power. When it comes to DC there's no reason not to use a single FET. Secondly, many chink charge circuits have an option to set the charge current with a resistor, which would be a pretty good option.
Otherwise, charging a lithium ion with a smart controller could definitely work, I'd use a buck converter with the MCU for current and voltage feedback instead of raw PWM though. It's a fairly flexible project, especially if you program the arduino to have a potentiometer/rotary encoder to set the charge current. Add a progress bar and current readout and you've got a pretty nice project, even if a chink circuit would work just this time.

>> No.1602290
File: 19 KB, 450x450, 61z+nW6a4pL._SY450_.jpg [View same] [iqdb] [saucenao] [google] [report]

>SSRs are only for switching AC power
How embarrassing.

>> No.1602306

Well I guess you got me. So it's a MOSFET with galvanic isolation and large heatsink capability? Ok I guess, but are there any uses for one? Most use cases where you're switching high DC currents you'll be doing so at slow enough speeds that a normal relay is a better choice. And even for cases where you're PWMing some DC load, 99% of the time you'll find it easy enough to just use a MOSFET with the control circuit referenced to the same ground as the power circuit. And even if your ground references don't line up for whatever reason, you could just use an optocoupler circuit and normal MOSFET with a heat sink of the same size and get the same current-carrying capability as an SSR for a 10th the price.

>> No.1602332

oh wow they just now announced a web version:

>The biggest takeaway from the GitHub discussion is that there simply aren’t enough developers for Fritzing. Fritzing is written in C++ and Qt, and there simply aren’t enough skilled devs to work on it. Future versions of Fritzing will be written in JavaScript.

the Fritzing devs are literally too dumb for C++

>> No.1602396

how does one charge an SLA battery? I know of trickle chargers but I think they're only for topping off rarely-used batteries, not for actually doing a recharge of a fully discharged SLA battery.

>> No.1602408

you could trickle charge a battery from the fully discharged state but you'd be waiting a long while
if you're in a little more of a hurry, you would use a constant-current constant-voltage scheme, with limits approximately 1/10C current and 2.3V/cell unless the datasheet for the battery says it can take more

to be fair, C++ was born under some truly shit design constraints
and a large UI is a pain to build declaratively

>not just connecting an inductor and freewheel diode to a PFET and switching it on and off with the PWM feature of the lolduino, using analog inputs to read current and voltage

>> No.1602436

>Ok I guess, but are there any uses for one?
Think industrial. Think of them as a time-saving, COTS, value-added lego module that any monkey can install in a PLC panel that gives you the advantages of solid-state switching over mechanical relays; without having to design a module with optoisolation, trigger circuitry, drive circuitry, and heat sink mounting.
Sort of the same reason you might use an off-the-shelf SMPS instead of designing your own for every project.
The market supports DC SSR's existence, so somebody out there sees the point.

>> No.1602439

We are in the end times of computing. Babel tower of programming languages.

>> No.1602446

fritzing is dying?
fug, but there isn't any other good alternative
kicad and the like are overcomplicated pieces of shit

>> No.1602448

no, just ported to a new platform
no, you're just a hack

>> No.1602449

just follow a simple tutorial
kicad is unintuitive but not that complicated

>> No.1602455

Is it bad to have different solar cells in parallel?

>> No.1602461
File: 109 KB, 680x863, Clipboard01.jpg [View same] [iqdb] [saucenao] [google] [report]

Starting to doubt if this will work.
I looked inside of the battery and there is a fucking supercomputer in there.
What the fuck is all that shit for?

>> No.1602469

Those are just transistors, probably power mosfets, and a mosfet driver or microcontroller in the center

>> No.1602479

why don't you look up the chips and answer your own questions

>> No.1602570

Comment from the current maintainer:
"The article is misleading, the releases planned here are based on the current code (that is in C++, just to be clear)."

>> No.1602573

>What the fuck is all that shit for?
current limiting and voltage monitoring

>> No.1602601

How old radios amplified uV from the antenna tto V? A bunch of common emitters in series (like 4 or so) and a power gain stage at the end?

>> No.1602620
File: 14 KB, 319x91, cc.png [View same] [iqdb] [saucenao] [google] [report]

In DC conditions, what happens in the following circuit?
I'm asked to find the voltage and energy of the 80uf capacitor, but i can't understand at all what happens.
Given that in -DC conditions- there's some flow at least until the capacitor fills, what would happen here?

>> No.1602629

1. Q=C*V
2. KCL (applies to charge as for current).

>> No.1602642

Well considering there's no resistance, they have to be asking about the steady state, so you'd have to basically turn the whole thing into a voltage divider question. Or use node/net analysis or whatever. You might just be able to imagine each capacitor as a resistor with 1/C resistance and turn it into an actual voltage divider, which would be pretty easy to sort out, and would avoid dealing with things in terms of charges.

>> No.1602645

Voltages from left to right: 90, 60, 12.
Charges (μC) from left to right: 2700, 1800, 840, 960, 960.

>> No.1602660

what is the name of the phenomenon where, over time, the flow of electrons actually physically moves the atoms of a conductor to one end of the material?

>> No.1602661

Excellent method!
12V 80µF 5.76 mWs

>> No.1602663

Electrostatic induction? Skin effect? The fact that a net charge will always be on the surface of an ideal conductor because the electric field within it must be zero? Need more context.
>moves the atoms of a conductor to one end of the material
I don't think this happens, since the material is nothing without its atoms.

>> No.1602665

It's an actual effect, I've read articles on it. I just can't for the life of me remember what the hell it's called.
It's an issue only on extremely small scales, like on the scale of computer processor transistors and microelectronics

>> No.1602667

Found it, it's called "Electromigration"

>> No.1602679

>The earliest commercially available ICs failed in a mere three weeks of use from runaway electromigration, which led to a major industry effort to correct this problem

>> No.1602693

Thanks for the help anons

>> No.1602703

Thanks for the interesting problem.

>> No.1602757

What's the simplest oscillator one can build out of some caps, inductors and transistors?
Simpler than Colpitts/Hartley preferably.

>> No.1602765

A 2-transistor relaxation oscillator? They're pretty reliable, and you could probably fix it to use LC delays instead of RC delays, if you really wanted to. I think that would give something of a sinusoid too.

>> No.1602766

that looks great actually, thanks!

>> No.1602768

you're roughly correct for most of radio history, with a few resonant circuits and crystals added here and there. compare the superregenerative receiver, which is basically an amplifier with a tuned circuit on the verge of oscillation

the mains is a hostile environment. the MOVs are placed to protect the circuit from anything that has gotten past the Ls and Cs. common-mode choke coils are made to withstand a few kilovolts for a whole minute

operating on what frequency, built with what construction method? Colpitts/Hartley are pretty simple as oscillators go. maybe look into the Clapp oscillator. bias with trim pots to start

>> No.1602774

>common-mode choke coils are made to withstand a few kilovolts for a whole minute
I see now that common-mode chokes are made with a >2-3mm gap between the two windings, though mine was salvaged from an old appliance and has some insulation scratched off the outside. Nothing a little CA or epoxy can't fix.
Since I plan on using the MOV in conjunction with a PTC thermistor as a resettable fuse, would it be advisable to keep the thermistor at the input side and have the MOV at the output side?

>> No.1602779

Can I use a zener instead of a transistor?

>> No.1602782

No? Why would a zener be a replacement for a transistor of all things?

>> No.1602784

the MOV is placed to help trip the fuse in case of overvoltage

>> No.1602789
File: 1.14 MB, 1140x1128, 1556324108540.jpg [View same] [iqdb] [saucenao] [google] [report]

>>I have junk, what do?
>Take it to the recycler.
Why I do it wrong? I wanted to return laptop bricks that were broken, and in result I got another 4 laptop bricks, 3 of which are working.
I can't sell that much power supplies...

>> No.1602791

Somebody in Youtube said they operate on a similar principle, but I couldn't find any info online.

>> No.1602793

what they meant is that a transistor is essentially two zener-like diodes *in theory*, but how they operate are anathema, likewise for their applications and usage. You can't just stick two diodes together and make a transistor.

>> No.1602796


>> No.1602801

I see, thanks anon!

>> No.1602804
File: 51 KB, 465x692, 48417172_529058320946467_6990156761407684608_n.jpg [View same] [iqdb] [saucenao] [google] [report]

no problem. Reading that article over it kind of sucks. I was going to try and provide more info but I just went through my electronics encyclopedia and also The Art of Electronics and neither elucidate on the Transistor diode model. It's an interesting theory, look into it from better sources.

>> No.1602815

I will admit I haven't really seen that model before, I'll check it out more, thanks!

>> No.1602842
File: 266 KB, 756x1008, IMG_8282.jpg [View same] [iqdb] [saucenao] [google] [report]

I don't know what I'm doing wrong, everything I look up says the yellow wire is just a tachymeter and doesn't need to be connected for the fan to spin. The battery box has two rows of AA batteries and my multimeter says it's at 12V which should be enough for the fan. But it's not spinning, I've tried nudging it to get it started but that didn't work. What should I try next?

>> No.1602850
File: 87 KB, 1168x657, IMG_20190501_082643.jpg [View same] [iqdb] [saucenao] [google] [report]

Im trying to make a "Keep Talking and Nobody Explodes" game board (the one where all of the modules are). This is my board.

The problem is that i want the modules to be removed with screws, because of the pcb sizes, i need to use standoffs. I cant find standoffs with longer outside screw length. I cant secure the bottom of the standoff, because its outer thread is too short.

Any ideas on what mounting system i can use? Maybe even something completly different. I just want the modules removable and exchangable.

>> No.1602851

do you have a friend with a 3d printer?

>> No.1602852
File: 110 KB, 1168x657, IMG_20190501_083525.jpg [View same] [iqdb] [saucenao] [google] [report]

With modules

>> No.1602853
File: 75 KB, 1168x657, IMG_20190501_082737.jpg [View same] [iqdb] [saucenao] [google] [report]

I could maybe get acceses to a 3d printer.

Picture of the standoff

>> No.1602859

I don't know anything about music, but I want to make some stuff for making weird musical sound effects like a synth with turbopositronics. Do not concern yourself with what turbopositronics are, just that they can function analogously to electronics. So turbopositronic analogs of VCOs and amplifiers are available, what else do I need to make an interesting sounding device? Are there any interesting music signal processing devices that don't need keyboards? I would like to make some turbopositronic music signal processors to sell to hipsters.

>> No.1602861
File: 5 KB, 195x259, images.jpg [View same] [iqdb] [saucenao] [google] [report]

Is this consider fully isolated???

>> No.1602876

There are chink services that will make you a pcb from a gerber file, but are there any cheap services that will also put actual components onto that pcb?
so you can have the pcb shipped to you with most of the components in place, since most of the stuff is very standard such as smd resistors so all chinks have them on hand

>> No.1602885

Yeah, I know SeeedStudio offers it.
There are probably cheaper options too.

>> No.1602887

Bike got stolen, what's a good circuit that uses a loop of thin cable I can put around my next bike that will protect it? I'm thinking it would be easy just to use the wire, a big pullup resistor, a FET, a coin cell, and a buzzer so when the loop is broken it releases a loud noise. Might even be able to get rid of the current wasted by the pullup by using a JFET or other depletion-mode FET. However, that would be too easy to counter by taping the two ends back together, and has no method of safely unlocking it. For either to work I'd need a latching circuit of some kind, and I'd want to make the battery life as long as possible. Is an MCU like an ATTiny on standby likely the best way to go about this? Also circuit ideas.

Yes this is the anon who was designing bike lights like 2 years ago but stopped because the circuits were awful.

>> No.1602895

posted this in the arduino thread:
any EE's here? Whats the current opinion on using arduino's for prototypes? I recently did a prototype for my senior project using an arudino nano and a couple of enviornment data gathering sensors, just dont know if it'd be something worth putting on my resume since its arduino based and not a different microcontroller.

We used arduino because we procrastinated building the project using a tivaware microcontroller and the arduino was faster to put together without days of debugging.

>> No.1602897

I think it's perfectly reasonable for use with prototyping, no reason to go the hard way. But I can't say I've ever looked for jobs as an EE so I couldn't answer your final question.

>> No.1602904

Arduino is fine even for production use in some cases.
People think that arduino is bad because it is super simple to develop software for it. Professional chips should be super hard to program, the high difficulty and steep learning curve makes them professional.
This wide spread opinion is beyond retarded .

>> No.1602910

We use it sometimes here at the uni. Microcontroller classes on the control system engineering are taught using the atmega328. I use it when I have a class that involves a project and I can't be bothered to make something smaller with pics.

>> No.1602918

when the alarm goes off they're just going to grab the bike and run
it's fine, but the chips are kinda shitty and overpriced.

>> No.1602920

>People think that arduino is bad because it is super simple to develop software for it
>Professional chips should be super hard to program, the high difficulty and steep learning curve makes them professional.
No you mongoloid, people think it's bad because it's bloatware that uses processor time inefficiently, hence wasting power, and fills half the damn MCU up with libraries that you only use one or two functions from. There's even a hard-limit on the maximum bitrate you can feed back to your computer with the serial write function, if I'm remembering that correctly. While not as obvious on an ATMega, I ran out of room on my ATTiny85 digispark to put even 100 lines of code after installing a couple of libraries.

It's the same with programming languages. Hey why doesn't everyone just program in python because it's easy instead of C or Haskell which are deliberately made to be difficult? The answer being the same, it's slow, inefficient, and lacks certain more fundamental features. To do anything useful with it you need countless libraries of bloaty, crowdsourced code. Much like arduino, there's not much wrong with using it for high-level simple interfacing work, unless time is of the essence.

>when the alarm goes off they're just going to grab the bike and run
It would be locked to the bike, like with those locks that go through the disc brakes of e-scooters.

>> No.1602932
File: 107 KB, 1080x1920, Screenshot_EveryCircuit_20190501-132453.png [View same] [iqdb] [saucenao] [google] [report]

I can't get this to work the way I want it. I want the output voltage from the opamp to be x10 (so 981mv) of the current going through the shunt.
But changing the resistor values around gives me shit results. What am I missing here?

>> No.1602935
File: 18 KB, 413x550, brain.jpg [View same] [iqdb] [saucenao] [google] [report]

You are aware you can program arduino in assembly and use lower level functions of the atmega328p? Arduino tards are retards for other reasons, you are a retarded for not using things the way they are supposed to be used.
>look function
>take function you need
>use it instead of the damn whole library.
Arduino is just a tool, like PICs and MSP and PLCs, don't blame a tool for your shortcomings.

>> No.1602938
File: 47 KB, 1143x661, Untitled.png [View same] [iqdb] [saucenao] [google] [report]

I don't have time to see what is wrong there, but there is a nice current sensing circuit that uses opamps and transistors.
270 ohm is the load, 100 ohm is the shunt and the others set the gain.

>> No.1602940

The output is the voltage at the emitter .

>> No.1602953

how did it go anon.

Had a blast in calc II, but mainly bc I was good at it. Calc III was most difficult for me but I think they were both professor combinations. Calc III prof made me feel challenged like I was at ivy league, although he did not teach very well

>> No.1602958

I honestly think this should be in the sticky but last time I added something useful someone took it out for the stupid fucking no cigarette meme

head over to http://the-eye.eu/public/ and into the electrical folder. It has more books than you would believe, but will require a tad bit of work on your part (member ctrl-f). I would recommend, but I can't.

>> No.1602961

I lol'd initially, but really this progression makes no sense. Can't tell if it's deep irony or just shitty effort

>> No.1602967
File: 38 KB, 638x521, file.png [View same] [iqdb] [saucenao] [google] [report]

tinyurl.com y4bjo7gw
about as close to your ckt as necessary to get wats going on (but use my link). now that it's working try adjusting one of the feedback resistors (5% tolerance e.g. would be 100k -> 105k) and you'll quickly see why this circuit kind of sucks out of theory. I recommend the other anon's. (wire's crossed because it's inverting by nature)

However, this is a classic basic ckt and you need to work on theory if you do hope to evolve

>> No.1602968

of course!! now when your circuit pops the only thing standing between gnd and 120 Vac is you!

sarcasm aside if that was your personal touch to the plug and you don't know what you're doing, don't

>> No.1602976

Here, the transistor is used to amplify the voltage from the opamp?

Oh, i see where i was making the mistake while calculating the resistors now, thanks!

I am not exactly the lowest resistance wire on the spool when it comes to electronics, so i am starting with designing the stuff i need with as few parts as i can get away with, since i get confused easily

>> No.1602989

You could solve the circuit. You just have to consider
You'll see the opamp serves to put the load voltage at the collector.

>> No.1602991

Also the circuit you built there, the diference amplifier is kinda shitty to do in practice at home (atleast for current sensing), mostly because cheap-medium opamps have input-output limitations and they have quite a bit of error (even the one with 3 opamps). If you do them in a breadboard soon you'll have a rat's nest that is impossible to troubleshoot.
Current sensing is not simple, and diference amplifier and instrumentation amplifiers are best bought that built.

>> No.1603007

microelectronics by sedra Smith discusses that model iirc

>> No.1603018

>put the load voltage at the collector
Load voltage doesn't appear

>> No.1603022

Computers typically follow the color code Black=Ground, Red = 5V, Yellow=12V

Try connecting the Black to the battery negative and the yellow to positive?

No idea what type of fan you have there. Most computer fans are 12V, but I'm just assuming you have a computer fan. Its possible that fan could also just be dead.

>> No.1603028

Find out what size the bolts threads are and just pick up some longer ones at a hardware store.

Or, Buy a long but thin bolt (like 6-32 at 1 1/2 inches) and push it up through the hole from the bottom of the board. Run a nut on it from the top to hold it in place.
Those will be your stands, you can stack more nuts to increase the height. Just drop your modules onto the bolts sticking up and use another set of nuts to secure.

>> No.1603029

Negative feedback of the opamp forces the two inputs to be the same. The voltage at the EMITER is proportional to load CURRENT because it is a CURRENT sensor.

>> No.1603030

No, on a 3 wire fan, yellow is feedback and red is the supply voltage.

>> No.1603031

Prototyping? Yes. To get something going fast and dirty its fine.

Production? Hell no. Its a terrible and crappy thing. If you show it off to friends, it may look cool, but thats it.

If you try to get a job in the engineering field, I dare you to use and arduino examples in your resume, you'll get laughed out of the office.

>> No.1603033

I got in as a 6 month intern at a paper mill because of some projects I showed, some of the were lolduinos. (I just bootload it and used only the chip kek.)

>> No.1603036

'Arduino' is the bootloader system. You also have physical specs for things like expansion boards.

If you get a real programmer and get rid of the bootloader so you can program in pure assembly, or code directly to the atmega, you as no longer using the arduino bootloader, just hardware specifics.

They are HORRIBLY inefficient and slow compared to a straight atmega coded in MPLABX and flashed straight to memory.

The Arduino IDE doesn't care about efficiency or code size, its designed to be simple for those who can't grasp bare metal designs. Its a good entry point, but once you get serious, its just toy after that.

>> No.1603037

I was telling you the normal colors for an ATX standard PSU

For an ATX fan:
Ground: Black
Power: Red or Yellow
Feedback: Yellow, white, or green

Again, assuming that is in fact an ATX standard fan. If you get nothing from 12 volts to black and red, its dead.

>> No.1603039

That's what I said, just quantitatively.

>> No.1603040

>Intern at a papermill


Its because the duino platform is premade and there isn't a lot of actual building involved. A lot of the more difficult work and real engineering is done for you. People looking for talent in the field know this and aren't impressed.

>I just bootload it and used only the chip kek.
At least you built your own circuit. I highly recommend learning to program and build from scratch without the arduino garbage

>> No.1603041

>I was telling you the normal colors for an ATX standard PSU
Yeah I know. But PC fans don't follow that color code.

>> No.1603042

I did the others with PICs and analog stuff. I was just in a hurry. Jesus fuck people you are autistic. It's just a tool. Use it when it suits you. Also
>using uCs instead of PLCs EVER

>> No.1603048
File: 240 KB, 1536x2048, IMG_20190501_171356.jpg [View same] [iqdb] [saucenao] [google] [report]

I had no idea we had this sort of technology. There is no battery and yet it spins when it gets hot. Fucking how?

>> No.1603057

why don't you use the spacers with both ends female and add thread locker to the bottom half only?

plenty of board houses offer PCBA services, the best thing to do is ask
also there's an outfit by the name of Macrofab, in NYC, that looks to offer a reasonably priced service built in the USA

hey bikeanon, how you been?
anyway just use a micro, you can then pulse current into the cable for continuity checking and also latch as needed. could also add a shitty little IoT module with GPS to find out where your bike's rolled off to

here's a nickel, get yourself an RRIO op amp
t.someone who had to work up a high-side current sensor just yesterday

>8-bit AVR
>current year

last time I did a project with PICs and showed the shop, it got me fired
t.maybe should not have hooked that radio remote controlled switch to the e-stop on that press

>> No.1603058

Seebeck junction

>> No.1603060
File: 3 KB, 363x227, d915e53ad6a77678cb974ebaca8eaabf.png [View same] [iqdb] [saucenao] [google] [report]

Is CD4093 really one of the most versatile in the CD4xxx series? Each input pin of its four NAND-gates has schmitt trigger circuits, making it suitable for working with analogue as well as digital signals. Can be used as:
- oscillator
- on/off controllable oscillator
- pulse shaper
- delay generator
- simple voltage comparator if great accuracy is not required
- two gates can make a basic R/S flip-flop

>> No.1603062

Is that another name for peltier?

>> No.1603067

Yes, or a TEG (Thermo-Electric Generator).

>> No.1603077

Dunno if this is a good place to ask, but a townhome I'm looking to purchase had some major electrical damage in the main panel.

Every single neutral wire was burnt to a crisp thru the insulation.

I suspect the seller is unwilling to pay to fix it, but I'm curious how much it'd take to have someone come out to begin with?

>> No.1603078

And to think i carried around solar panel s like afaggot when camping in forests when all i need is a 4x4 square that will give me 1A when I start a fire.

>> No.1603081

>last time I did a project with PICs and showed the shop, it got me fired
this displeases big clive >:(

>> No.1603084

The heat sink is necessary though, so you're still packing weight.

>> No.1603085

Why? Do you need to make sure one side is colder?

>> No.1603087

It produces power based on the difference in temperature between the two sides.
Heatsink the side you want to keep cooler

>> No.1603088

you are asking what is ultimately a legal and labor-market question pertinent to a particular jurisdiction, not a question of physics. see /ohm/ rule 0

yeah, it decoded the HT12 protocol in software and switched a couple of relays on/off according to commands. the plan was to drive one of the other techs into rage with a press stopping at random. good times

>> No.1603091

That is not a problem, big aluminum heatsink s weigh nothing and are much smaller than solar panels and unlike sun you can start a fire anytime you want

>> No.1603099

Doesn't beat a small Sterling engine as generator though.

>> No.1603102

In a regular DC circuit, what do we refer to when we talk about the voltage of, let's say, a node ''A''?
The voltage across a passive component, or a voltage source is measured across its two terminals, but what determines the voltage of a node, then? If it's just a dot, what is it compared to?

>> No.1603108

Have fun carrying that around with zombies behind your back

>> No.1603114

>thread locker
Hmm, i would use it in a wooden board, would it still work?

>> No.1603118

>what is it compared to?
Another node, e.g. the common reference called ground.

>> No.1603120
File: 65 KB, 1000x750, 1550980025368.jpg [View same] [iqdb] [saucenao] [google] [report]

the potential with respect to that of some chosen zero point in the circuit, usually called "ground", often the most negative potential in the circuit

Pic related. might use something else grippy on the non-detachable half, so that the wood won't compress and leave your firmly threadlocked screw flapping in the breeze. hot snot? a spring/serrated/star washer or combination thereof?

>> No.1603121

>voltage <=> height in a gravitational field
>Voltage law <=> if you climb a set of stairs and then go down the same set of stairs you end up at the same height you started at

>> No.1603142


I'm not that other guy btw. If the fan wasn't dead before, it is now, because I tried connecting the yellow wire to power and it started smoking. The yellow wire is indeed 5V, but I think since it's a tachymeter, it is an output and wouldn't need to be powered. At least that's what I gathered from reading online.
I think I'll just order another fan, this time a two-wire so it's as simple as possible.

>> No.1603164

>diference amplifier
in almost all cases i need an opamp to take a difference between + and - legs and amplify it by some number like 10 or something
I thought op amps are only sold as bare op amps, do they sell special versions with resistors and stuff in place, so you only have to hook up your shunt?

>> No.1603173

So, let's say I have an IC which is only 5V tolerant and I have 10 Voltage supply.
So i create a square wave that is 50% on 50% off to create 5V. How many iterations of this square wave do i have to execute per second to not damage the 5V only IC and make it go like "wow this is totally 5V"

>> No.1603177

If you use a pair of potentiometer, a pair of op-amps and a h-bridge circuit, can you make a brushed DC motor stay at a fixed angle? The second potentiometer would be used to determine where the motor is, and the op-amps would compare its output to the first potentiometer, making the motor turn either left or right until it got to the right point.

>> No.1603183

>How many iterations of this square wave do i have to execute per second to not damage the 5V only IC and make it go like "wow this is totally 5V"
Give up on this line of thinking immediately, it will not work how you think it does. Look up buck converter instead.

>> No.1603184

what you do is
how much current does ic draw
design rc filter to smooth out square wave

>> No.1603196

Yeah they do. Opamp is not only a "chip", it's a circuit like any other, so you can have a IC with several opamps inside that is not actually an opamp itself.

At core the opamp does make the difference of two inputs and multiply it by something, but that something is very large, that is why they are used in closed loop; to select the gain you want.

The circuit you describe is usually sold as a "current monitor" or similar names. They are done in a single package because then you can use very precise values for your circuit. In some applications a 5% or 1% error is not allowed.

>> No.1603228
File: 56 KB, 806x728, 1530493686533.png [View same] [iqdb] [saucenao] [google] [report]

let the load guide you

>> No.1603232

>pulse current into the cable for continuity checking
Wouldn't it be better to use the cutting of the cable as an interrupt? Whichever one takes less power I guess. Ideally I'd put the thing in the frame so it can't just be bashed off, so replacing batteries wouldn't be an easy task. I might look into energy harvesting, either with IR LEDs or some sort of antenna.

>> No.1603280

>Wouldn't it be better to use the cutting of the cable as an interrupt
I meant "pulse voltage onto the cable". note that you'd be drinking pulldown energy the entire time it's locked, until the lock is opened or cut, vs. it only takes a microsecond or two of current flow to check the continuity status, and you could disable almost the entire chip the other 99.999% of the time
>energy harvesting
I'd think a linear alternator would be well-suited for a human-pedaled bike

>> No.1603300

Well I suppose checking once every second or so is easily fast enough. But would waking it for 1ms every second waste more power than a 10M pullup? Pic related, the 50k pullup required for the MCU itself (if I'm reading the datasheet correctly) is active only when the loop is cut.
>a linear alternator
Could be a pain to get in there, but if a single magnet strapped to the wheel with an inductor near it would work then I could definitely go with that. Just did some dirty calculations with Lenz's law, looks like getting a decent voltage with a tiny magnet like that won't be too difficult at all. Plus I can use it to measure my speed.

>> No.1603301

I'm gonna be perfectly honest I didn't read the rules. Thanks.

>> No.1603405

right there with you brotha
shouldn't you know lol (subject wise)? I still haven't taken an Algorithms class and I haven't taken CS for almost 3 years

>> No.1603423

what is the correct work order when soldering smd stuff?
In some tutotirals they only use solder but in others there are many more steps
>ejaculate flux goo everywhere
>melt with hot air gun
> put a bit of solder on your soldering iron's tip
>rub over smd
>remove any excess solder with john wick
>wipe away flux goo with alcohol
is that it?

>> No.1603426

you gotta put the components on the board bro

>> No.1603433

What's the cheapest rasp pi that I can use to make a pi hole? Something wired preferred

>> No.1603434

orange pi zero?

>> No.1603437

there aren't that many. only the big ones have ethernet like the pi B etc, zeroes are wifi only and are very weak, but they are awesome if you need a cheap "arduino" that runs linux on it

>> No.1603530
File: 9 KB, 458x365, colpitts-oscillator2.png [View same] [iqdb] [saucenao] [google] [report]

Brainlet here again, how is it in a circuit similar to this, the amplitude of the output doesnt go to infinity?
The way I'm thinking of it is, the oscillations in the tank circuit get fed to the amp, which then adds current according to the direction of the oscillation, but then shouldnt thay feed even more current to the base, which would feed even MORE current back into the tank, and infinitum or until something blows out?

I understand why LC circuits oscillate, but it seems like an amp would just keep feeding it energy in one direction until something blows out. Of course I know this ain't true since they work, but I'm not sure what I'm missing.

>> No.1603542

Is this the perfect power supply for Ts100?

>> No.1603544
File: 660 KB, 1922x1437, 1509827171954.jpg [View same] [iqdb] [saucenao] [google] [report]

>buy 20 JRC4558D op amps for €0.80 from aliexpress
>despite knowing they're most likely fake and unusable garbage anyway
Why do I keep doing this to myself?
Must have wasted at least €100 like this over the last couple of years.

>> No.1603574
File: 23 KB, 298x678, colpitts.png [View same] [iqdb] [saucenao] [google] [report]

No infinitum. An amplifier limits its output by clipping above a certain level. To get a clean sine you set the loop gain to just cover the losses, such that the clipping is soft and the sine shape has as little distortion as possible.

The image only shows the principle of the Colpitts oscillator, no power supply, no biasing. The circuit at the bottom is even more simplified. You see that the LC circuit acts as a π filter that can be used to match output to input by means of the C1 to C2 ratio, like a transformer. When you tap the inductor instead of the capacitor the circuit changes its name to 'Hartley' oscillator.

>> No.1603584
File: 215 KB, 640x480, O2Bypass01.jpg [View same] [iqdb] [saucenao] [google] [report]

I'm a fucking idiot and forgot entirely what we discussed last time I brought this up.
A buddy wants me to do this mod for him, but I wanted to shrinkify the design quite a bit. I guess I could just order the shit and tape it all up instead of putting it into an enclosure, but I also wanted to know how durable the components originally used are in an environment like the engine compartment of a truck used for wet/muddy/dusty conditions.

Can someone remind me?

>> No.1603596

you ain't getting MUSES amps, to be sure, but a 4 cent audio op amp is a 4 cent audio op amp. not to over-shill but LCSC has the perfect combo of low prices AND the knowledge that your chips weren't skimmed off the top of Wun Hung Lo's solder pot

those in the picture are pretty durable but I still wouldn't leave them naked in a hot, high-vibration environment like a vehicle under-hood. in particular, I would look closely at the temperature ratings for that capacitor
one good, economical way to shield components from the elements would be to pot the entire finished circuit in epoxy
also, you can search the diy archives for your older discussion, where you included the same yotatech link

>> No.1603655

are there any feasible DIY methods to smooth the output of a modified sine inverter so it doesn't fuck up small electronics as much

>> No.1603671

Why not use a wall wart

>> No.1603681

motor/generator with a huge fucking flywheel/harmonic dampener on it.

>> No.1603692

if everything was easy life would be boring

>> No.1603694
File: 218 KB, 1532x518, 1547433464592.png [View same] [iqdb] [saucenao] [google] [report]


>> No.1603728
File: 10 KB, 611x330, FOOBVLYI74L94WZ[1].png [View same] [iqdb] [saucenao] [google] [report]

How could this even work?
If you try to limit the gate voltage in order to limit the current the resistor will do nothing since gate current is always zero, so there won't be any voltage drop over the potentiometer

>> No.1603739

while BJTs are current-controlled current sources, FETs are voltage-controlled resistors and draw negligible current on their gates. you would therefore instead sample a voltage point, in this case from a voltage gradient across the length of the track of the pot

>> No.1603744

what's stopping someone from using an oscillator like a colpitts oscillator as a type of inverter

>> No.1603761
File: 13 KB, 229x177, bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb.png [View same] [iqdb] [saucenao] [google] [report]

what are these doodads on the output of this opamp?

>> No.1603769

Thank you, would you be able to explain how a BJT acts similarly to an op amp with an inverting input?

>> No.1603774

it's a transconductance opamp. that's a current mode output. you can do some fun tricks with those

>> No.1603790

A: you'd burn a bunch of power in the transistors
B: your output frequency and amplitude would be dependant on the load
C: inverters are basically useless for powering anything that doesn't use an AC motor or transformer since SMPS devices can run fine off HVDC instead

>> No.1603803

there's always a 9 volt drop on the potentiometer there. Current doesn't need to move out of the middle pin to make it still divide the voltage.

>> No.1603810
File: 56 KB, 800x447, inverter-circuit.jpg [View same] [iqdb] [saucenao] [google] [report]

>an oscillator like a colpitts oscillator as a type of inverter
Not a colpitts it's still a feedback oscillator

>> No.1603811
File: 656 KB, 758x866, Annotation 2019-05-02 184800.png [View same] [iqdb] [saucenao] [google] [report]

Browsing through an archive and wondered what you fellas though about this 'breadboard' technique? I think I'm going to try it out, bc dead bug sucks ass when a single pin on your 14 pin dip falls off. Also not a fan of vero style boards, seems like you either pay too much or get POS chinky boards

>> No.1603812
File: 53 KB, 500x380, 1546731440822.jpg [View same] [iqdb] [saucenao] [google] [report]


>> No.1603827

>Father is an awesome handyman and electrician
>I'm mediocre at best when it comes to handyman work
Fuck genetics
Based pa, anyways

>> No.1603838

I know my buddy went the apple watch route a few times. I think it was for biology or etc(med) tho, might not fair as well in EE. In a math class, I forgot some definitions and went to the bathroom and just looked up shit lol. I never know if they care

>> No.1603845

>PCBs and components will not ship together from today because of a customs declaration issue.
>Please enjoy hueg shipping discounts

>> No.1603848
File: 148 KB, 1000x750, stunneded.jpg [View same] [iqdb] [saucenao] [google] [report]

>went to the bathroom and just looked up shit
qaulity control!
they won't even let you do this when sitting a ham exam

cute! I do something like this, but with copper tape instead of tinned wire, and with SMD instead of THT, but the ground plane is nice
>14 pin dip
>current year

>> No.1603855

so it's not a separate component, it's just showing the form of the output of the opamp?

>> No.1603866

it's part of the OTA symbol, an illustration of one of its features helping to distinguish it from other architectures of op amps, including the more common voltage op amp. e.g. Norton op amps (current-differencing amplifiers) will have an arrow representing current between the + and - inputs

>> No.1603890
File: 111 KB, 1756x757, bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb.png [View same] [iqdb] [saucenao] [google] [report]

I know it's a second order filter but something tells me it's not supposed to be only generating like 20 millivolts

alright now it's making a lot more sense. I'm trying to figure them out so I can do more signal processing stuff with them like active filtering and synthesizers, etc.

>> No.1603946

I'm going to have to choose my specialization soon.
What's the job market like for those who specialize in Signal Processing?

>> No.1603976
File: 526 KB, 996x1600, nigger what you doin.jpg [View same] [iqdb] [saucenao] [google] [report]


>> No.1603978
File: 120 KB, 620x1004, bitch what you doin.jpg [View same] [iqdb] [saucenao] [google] [report]


>> No.1603979
File: 35 KB, 412x600, fine ass legs.jpg [View same] [iqdb] [saucenao] [google] [report]

Might as well have this too

>> No.1603988

I want to get a blow gun like that, do i need the whole ugly brick station as well or can i power the hand held heat gun from my lab bench power supply?

>> No.1603990

If you have a big enough relay and lead you can power it from your kitchen.

>> No.1603993

They need quite a lot of power, so your lab power supply won't work.
They are powered by mains, controlled with a triac.

I've seen diy projects that built their own controller for those handles.

>> No.1603994

>went to the bathroom and just looked up shit
Wouldn't you be looking down at shit then?

>> No.1604016

Both invert the signal: input goes up, output goes down, and vice versa. The (resonant) LC circuit inverts too, which lets the entire circuit oscillate. Right loop gain, right phase.

>> No.1604017
File: 74 KB, 928x437, BJT-FET.png [View same] [iqdb] [saucenao] [google] [report]

>FETs are voltage-controlled resistors
Not so simple. Better unlearn that meme, it only impedes understanding.

>> No.1604137

Does current across BJT go up as the base current go up ?

>> No.1604144
File: 782 KB, 4256x2832, 1534689518848.jpg [View same] [iqdb] [saucenao] [google] [report]

seems pretty reasonable. 6mA is a pretty high Iabc tho, maybe you need a smaller cap instead of those 10uF. also those linearizing diodes are not there to help gain

>can i power the hand held heat gun from my lab bench power supply?
depends on your bench supply :^)

if you mean collector-emitter current and the transistor is in the active region, then yes, by a factor of the transistor's beta, as long as there is current available (otherwise it saturates)

>> No.1604148

Yeah I did mean the collector-emitter current. But then how does this invert the signal?

>> No.1604150

Yes, the current through (not across) the transistor goes up. And if there is a collector resistor the collector voltage goes down because the current increases and the voltage drop across the resistor also increases.

>> No.1604154

I see, thank you, I think I get it.

>> No.1604169
File: 37 KB, 1331x147, this shit's better than fiverr.png [View same] [iqdb] [saucenao] [google] [report]

I made a chink do something for me for 4¢

>> No.1604193

Why... how... WHO sat down, deliberated an endless number of would-be models; who was it, that after considering an endless number of possible handsome studs, 10/10 females, aspiring youth talent, that THIS guy..this FUCKIN guy: "We need him in our modeling agency, and I know that this is my best possible option"

After typing that out I feel I kinda bad but damn just how did this pouty pea brain looking fuck make it through some selection process

>> No.1604247

>just how did this pouty pea brain looking fuck make it through some selection process
he black

>> No.1604248
File: 49 KB, 435x439, ch.png [View same] [iqdb] [saucenao] [google] [report]

I'm building a miniature lighthouse and need to decide on its light characteristic. I'm looking for something simple enough to build with discrete logic ICs, yet more complex than a simple NE555 flasher. Which one would you recommend.

>> No.1604263
File: 1 KB, 439x102, hi.png [View same] [iqdb] [saucenao] [google] [report]

Morse code equivalent of 'lol'.

>> No.1604375

I've been taking apart some old electronics lately, why are inductors so relatively rare? You see capacitors, tranistors, chips, everything, but not alot of inductors.

>> No.1604382

inductors are a bit more expensive than other passives, and most needs not having to do with power conversion, storage or filtration can be served about as well with other, cheaper components

he answered his phone when the stock photographer wanted to tick some diversity boxes

>> No.1604449
File: 20 KB, 437x321, Annotation 2019-05-04 144851.jpg [View same] [iqdb] [saucenao] [google] [report]

Why single supply comparator Vin go to negative input???

>> No.1604458

That's not the negative power rail. That's the inverting input.

>> No.1604461
File: 101 KB, 1650x808, LM13700.png [View same] [iqdb] [saucenao] [google] [report]

The fuck are you even doing applying 200V to that amp input bias pin. First problem is your 30k resistor is dissipating over 1.3W which is a lot, especially in an application like this and will melt standard 1/4W resistors. But the bigger problem is the absolute maximum amp bias current is 2mA (assuming the spice model is based on an LM13700, a very common OTA) and you're pushing nearly 7mA. Nothing about this makes any sense. Why?

>> No.1604542
File: 25 KB, 498x313, bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb.png [View same] [iqdb] [saucenao] [google] [report]

I was just basing it off of this Typical Application diagram from the 13700 data sheet. I don't know what the fuck I'm doing, and the only way I could get it to work was to set the bias to crazy high voltages.

>> No.1604552

The CS classes are the easy ones for me. I do a lot of hobby programming stuff, so that helps I guess. I have a good idea for the course material but I'm just praying the classes are actually good. My computer architecture class has been a bit of a dumpster fire, hoping the advanced one I'm doing next semester will be better.

I don't think I've ever read something so pands-on-head retarded

The pot always has 9V across it, the wiper makes it an adjustable voltage reference. Very little (practically zero) current flows into the gate so the voltage that would be seen at the wiper in a non-loaded scenario is basically the same as you'll get with the FET attached to it.

>> No.1604584

So far the Computer Architecture classes I've taken have been pretty abstract overviews of various ISA designs. Nothing really practical. Only my embedded and PLC classes have actually been practical

>> No.1604586

that would do it

>> No.1604619
File: 191 KB, 1200x900, power.jpg [View same] [iqdb] [saucenao] [google] [report]

Looking for a power supply like pic related.

I'd like a 12Vdc at 15A ideally, but a 13A would be the lowest I could do.
I can find a ton of 12V 10A, but nothing really higher without being massively higher, like 25A and costing way too much.
Any help? Thanks.

>> No.1604622
File: 209 KB, 550x550, file.png [View same] [iqdb] [saucenao] [google] [report]

can you use a chinese industrial supply? these should be cheaper per watt and available with more options online.

>> No.1604623

I have one of those that can supply 30Amps and it works great. I need one that is enclosed like in my pic because it will be laying around to power a system I built. I'd like it to be smaller and, like I said, enclosed.

But it is an option to get another smaller one, just not my ideal solution.

>> No.1604631

i wish you luck. a 180W supply close to its rated current will be dissipating a few watts inside that closed plastic enclosure, and the poor thermal properties of the plastic mean it'll get very hot internally. there's only so much you can squeeze out of that form factor even with expensive parts.

>> No.1604634

shit you're right, I completely forgot to change the default values on those caps

>> No.1604644

Thanks for the luck. The 180w rating is actually well above what the system will be using. I believe the system maxes out at 120watts full power but shouldn't go over 100w for 90% of the time. I'm throwing in extra power *just in case*

>> No.1604681

Where can I find schematics for a laptop motherboard (Toshiba Chromebooks 2 cb35)? Also, how do you fix such things without schematics. I have two in front of me, one broken and one working. I'm thinking of comparing voltages at random points, but it is very time consuming. Any ideas?

>> No.1604683
File: 3.26 MB, 3968x2976, IMG_20190504_221521.jpg [View same] [iqdb] [saucenao] [google] [report]


>> No.1604699

That's a nice idea. I like that.
Too bad it looks like it will require too many logic ICs to fit inside the lighthouse. There's only space for a 7*7 cm PCB.

>> No.1604722

It's the 'spot the ham' pattern. One 4017, two 555C, six diodes.

>> No.1604731
File: 60 KB, 1203x635, Untitled.png [View same] [iqdb] [saucenao] [google] [report]

Seems that wikipedia article on Injection locking wasn't lying. The time for frequency and phase lock depends on how forcibly I fuck with the oscilator, but it seems I can get a 45 hz thing follow a 60hz source.

>> No.1604755
File: 56 KB, 503x259, main-qimg-02b0d64bf42e7088e2f4d22c341d76ab.png [View same] [iqdb] [saucenao] [google] [report]

Let's see if I got it right. the sequence for "LOL" would be the following. Let's say lamp on-time of 1 second corresponds with a dot and 3 seconds for a dash. Each dot/dash ends with 1 dark second. And I guess some lamp-off time is needed at the end of each character, too? Let's say 3 sec.
L -.---.-.-
O ---.---.---
L -.---.-.-

Patterns (0/1: lamp off/on):
L: 10 1110 10 10 + 000
O: 1110 1110 1110 + 000
L: 10 1110 10 10 + 000

Combined, a single LOL cycle might look like this:
Which would be completed in 40 seconds.

>> No.1604767

a 3-beat space (total) between characters is customary. only + 00 instead of + 000. 7 space beats would be appropriate at the end of the message
so a total of 12+14+12+4 = 42 seconds, at like 1wpm

>> No.1604774

Yes, except what the guy in >>1604263
posted is actually the Morse /equivalent/ of LOL, which is exactly as it shows in the pic - it's HEE with an abbreviated space between the two Es. The shortened space has something to do with a carryover from a different telegraphic code, but I don't recall just now what the details are.

>> No.1604801
File: 12 KB, 628x383, morse-montagne-hi.png [View same] [iqdb] [saucenao] [google] [report]

You got it, the cw op code for "I'm laughing" is HI (not HEE), like .... .. or didididit didit or bleebleebleebleep bleebleep, like in the image posted earlier, also filename.

>> No.1604809

What are some DC voltage booster circuits?
I know how a boost converter works but I don't want to use a timer, I was wondering if there are more.

>> No.1604835

anyone know where to find the through hole solderable US mains prongs on digikey? their connector search is a clusterfuck.

>> No.1604846

>solderable US mains prongs

>connector search is a clusterfuck

"Mains prongs?
perhaps the clusterfuck is related to you search terms

>> No.1604847

somehow i doubt you tried searching that

>> No.1604866

>i doubt you tried searching that
I wouldn't bother.
I don't even understand what
>through hole solderable US mains prongs
I doubt if Digikey knows what they are either.

>> No.1604869

Usually you'd use some sort of screw terminal connector with mains prongs. Or an IEC plug soldered onto your board instead. If you're making a nightlight or doorbell that sticks directly onto the wall you might be out of luck.

>> No.1604879
File: 126 KB, 352x265, file.png [View same] [iqdb] [saucenao] [google] [report]

shame. i've seen pcb prongs on chinkshit before but i can't even find them on ali. i've found one random source so at least they do exist.

>> No.1604881

Can always just buy some copper or brass stock of the right size and go at it a bit with a file and drill.

>> No.1604890
File: 14 KB, 400x400, s-l400.jpg [View same] [iqdb] [saucenao] [google] [report]

What do I search for on aliexpress to buy some 2n2222 transistors with bent legs?
Have no idea what they'd be called, only have pic related because I came across it on an ebay just now.

>> No.1604891

oh these are fun

>> No.1604893

>with bent legs
but why

>> No.1604895

you want "formed" leads, but i don't see them when i search using that term. they'll definitely be on digi though.

>> No.1604904

For breadboards

Thanks very much
Strange how they're not on ali, I guess they might be under another term after chink to english translation, I'll keep looking for a bit.

>> No.1604936

>For breadboards
If it's not for mass-production just bend them yourself. I always bend them really weirdly to get their emitter sitting on the ground rail anyhow.

>> No.1605026

Boosting DC can only be done with switching converters. If you don't wanna mess with inductors and transformers you can use switched capacitor converters but they're usually kinda limited. They can typically only double your input voltage or invert it and they can't provide a ton of power either. They're usually used to generate negative rails from a single positive supply to power low power analog chips or to create a higher single supply voltage for them. Same shit effectively.

Also you don't use timers for switching converters. I mean, you can use a 555 to generate signal to switch your FET but it's kinda shit because there's no feedback so it's not regulated. You'd typically use dedicated controller ICs.

>> No.1605051

Well you COULD do feedback with a 555 into its reset pin with a zener or FET, but it wouldn't be terribly pretty.

>> No.1605058

>Boosting DC can only be done with switching converters.
Use a DC motor to power an AC generator.

>> No.1605070

That's A:
an inefficient rotary phase converter
and B:
still switching because you've got non-DC somewhere

>> No.1605078
File: 9 KB, 518x230, 555smps.png [View same] [iqdb] [saucenao] [google] [report]

>reset pin
Nixie fans have learned to use pin 5.

>> No.1605081
File: 55 KB, 800x649, FC9DX4EJAMTWCAX.LARGE[1].jpg [View same] [iqdb] [saucenao] [google] [report]

I was wondering if someone can help answer this question. In pic related here, theres a blue line going from D3 on the nano to the RX on the 8266, and my question is, if theres that 1k resistor already going from D3 to RX, why does there need to be 2k resistor soldered to 1k and then goes to ground? Whats the purpose, and its significance? When should I know to do that?

Also another semi related question, It seems some resistors can't transfer data only power? I tried flashing 8266 on biege colored resistors, then I had some blue colored ones (values were similar I think? this was a while ago, and didn't really cared about asking at the time) and blue resistor let me flash my 8266. If that's the case, what alternatives can I use to use rx/tx serial on 8266 with other devices that use 5v?

>> No.1605084

>voltage divider feeding an NPN
uh what

>using an ESP8266 as a wifi module
>using resistors as logic level shifters
why not just use it as its own standalone mcu, I don't understand
use fet-based level shifters instead bro

>> No.1605087

Don't get me wrong, I did a quick look into level shifters, and it looks like you need two different power sources? One for high, and the other for low?

>> No.1605091

oh nevermind, it seems you can use single power source as long as you use the correct voltage for high and low.

>> No.1605094

Does the 8266 not have a 3.3V output pin on It after the lin-reg? Anyhow those level shifters are for 2-way comms, 1-way comms can be done with resistors to step down, and I assume the Arduino's digital inputs are open-base/gate transistors that can easily run off 3.3V. Could use a voltage divider feeding the FET level shifter anyhow.

>> No.1605095

I want some simple way to detect power outage on my arduino so i can save data into eeprom before it shuts off.

I was thinking of using an opamp comparator where the + input is supply voltage and - input is a cap charged to 90% of supply voltage.
So if the power gets turned off, the supply voltage starts to fall rapidly and becomes lower than the voltage on the cap, so the opamp will output HIGH into an arduino interrupt pin and a simple function to save data is executed

Do you think this will work?

>> No.1605100

It's a little unreliable since comparators might not act as nicely near their rails, and somewhat relies on the voltage difference of the diode between the battery and the capacitor, but it's definitely simple and I think it would probably work. With the diode there (to stop the main capacitor from charging up the power supply's output capacitor), there should always be 0.6V or so between the PSU and cap when the PSU is running, so measuring when this voltage difference inverts should trigger the comparator when the PSU is shut off hard, but if the voltage drops slowly (like if the PSU's output capacitor is too large or if the PSU is replaced with a battery) the voltage of the capacitor will just remain 0.6V below the PSU and approach zero.

To avoid this issue you'd need to compare the voltage to a known reference, like a linear regulator (which you'd have anyway if you were running it off a battery) or a reference diode.

>> No.1605106
File: 2 KB, 242x146, pin5_ton.png [View same] [iqdb] [saucenao] [google] [report]

>uh what
the magic of pin 5

>> No.1605114

Or just use a dual comparator IC and waste less power with a more reliable oscillator with a similar amount of passives.

>> No.1605115
File: 225 KB, 2048x1536, IMG_20190505_110614.jpg [View same] [iqdb] [saucenao] [google] [report]

I am making this soldering and testing station i found on the internet
I hope it will be worth the time and plastic

>> No.1605116

Looks pretty flimsy, I'd check the actual filament cost and compare them to a similar product from ali.

>> No.1605118

A much smaller station like that on ali costs almost 30 bucks, mine will cost less than 10 and will be much larger and more modular, so as far as price goes there is no comparison

>> No.1605120

Yeah they are surprisingly expensive on ali. I'd print 5-10 of them and give it a test run in that case. Not sure if acetone vapour polishing would do them any good, but I doubt that scratchy finish would be terribly functional for bearing surfaces.

>> No.1605122

the photo is what i already made, the arms are working great, joints being rough is actually good because they don't slip and hold position well, i just hope they won't wear out too fast

>> No.1605124

>what i already made
Oh, I thought you were posting some other's creation and asking whether it would likely be worth making, which would be more of a 3dpg kind of post. But no if that's working then great. Surprised the chinks can't make them cheaper though, it's probably because they're using nylon or something for the main plastic.

>> No.1605129

>A much smaller station like that on ali costs almost 30 bucks,
Those just use flexible cooling pipes for CNCs.

You can get them much cheaper and then just print/diy a base for them:

>> No.1605130
File: 24 KB, 437x321, 456789.jpg [View same] [iqdb] [saucenao] [google] [report]

Why Vin go to inverting input for the single supply comparator???

>> No.1605131

circuit diagram please

>> No.1605134

other in use, no see?

>> No.1605138

Can you easily separate those joints?

>> No.1605152

>coolant pipes
m8 you're a fucking genius
This is probably a standard thread too so you can likely just jb-weld some nuts to a C-clamp and clip that on your bench or something along those lines. And somehow fix some sturdy alligator clips to the ends of course.

pretty sure

Look up "comparator oscillator" or check out this video: https://youtu.be/QLQrLO0zvDI. He calls it an op-amp oscillator, but since the v+ and v- aren't at approximately the same potential I think it's better done with a comparator. For single-rail purposes you just replace the single resistor to ground with one to Vcc and one to Vee, and the cap to ground just goes to either voltage rail. The other of the two comparators would be used to handle feedback via a voltage divider from the output. You can also take the "triangle wave" out from the capacitor, feed that into the other comparator and feed a potentiometer voltage divider into the it as well and get an easy PWM circuit. Look up "PWM triangle wave" if that doesn't intuitively make sense.

>> No.1605162

>pretty sure
That's great. Those things are really cheap as well I ordered a pack to try them out.
It's great them being hollow, since i can fit wires inside

>> No.1605165

>fit wires inside
For what purpose? Grounded clips? DIY endoscope?

>> No.1605172

>Look up
Thanks, known.

>> No.1605181

spring wired needle probes to have contacts on flat pads

>> No.1605235

I handwired a mechanical keyboard and i'm not happy with how it turned out so I am going to make a pcb and redo it. Can I drive a 3mm green ultrabright indicator led seriesed to a 1K resistor directly from a teensy++ 2.0, or will the current smoke the i/o pin?

>> No.1605249

learn Ohm's law

>> No.1605254
File: 32 KB, 490x328, btomtu.jpg [View same] [iqdb] [saucenao] [google] [report]

too complicated

>> No.1605257

I know ohms law, but thats useless without the specs which are buried under hundreds of pages of incomprehensible datasheets. google tells me a super bright green 3mm led draws 20ma, I don't know should I source or sink that current etc.

>> No.1605258

>computer dies
>pull the psu out
>12v rail drops to 9v when i draw 2a from it
welcome to the shitlist, seasonic

>> No.1605352

literally just remember VIRus

>> No.1605375
File: 733 KB, 1197x642, rigol kit.png [View same] [iqdb] [saucenao] [google] [report]

is this a good deal for a home kit?

>> No.1605382

unless you make fuck you money i don't think it's wise to buy that kit. if you're experienced enough on the hobby to know you need a function gen and benchtop meter, then you'd probably already have a psu and scope. if you are newer then just get the scope for now.

>> No.1605392

nah get usb scope for $60, make bench supply from a pc PSU + buck boost converter for $5 and a multimeter for $30 and of course TS100
that is all you need

>> No.1605435

I mean, all the equipment is reasonably good for a home setup sure... but is it a good deal? Not really.

Getting the Rigol scope on it's own isn't really a bad investment but the PSU, function gen, and DMM are all overkill. For a power supply you can find PSUs on ebay for as little as $40 and and if you want dual channel, which I recommend, it'll run you a bit more. They'll usually be somewhere around 60-120W per channel, 0-30V. You can get function gens super cheap. 0-2MHz function gens can go as low as $20. The Rigol unit does have an edge on cheap function gens since it's dual channel and probably goes up to 20-30MHz but for something just to get started, 0-2MHz is fine. Even if you want the 20MHz capability you can get used units for cheaper than the Rigol that will do it but you'll pay more between $70-200 for that. I got a Wavetek 288 that ran me somewhere around $80. For a bench DMM you can get a good Fluke or Agilent unit for between $50-$300 depending on the exact model and how patient or lucky you are. I'm relatively sure my Fluke 8840A didn't cost me over $100.

Point is, you can get the full gamut of reliable name-brand test equipment for under $1000 so there's no real reason to spend $1500. Nor is there any reason to waste your time with shit USB scopes and fucking around with ATX PSUs and chink boost converters. Cheaping out too much will give you nothing but headaches in the long run.

>> No.1605527
File: 10 KB, 680x54, ayy.png [View same] [iqdb] [saucenao] [google] [report]

Ctrl+f your way though the datasheet, pic related.
Also 1kΩ sounds too big, a green light will have a potential of 3V, so you'll need to drop 2V across the resistor at 20mA, meaning 100Ω is your number.

>> No.1605530

Again with this shit? For an on-the-go setup sure, but none of the rest of that is portable, so instead suggest one of those T12 stations that have the same features and go for half the price of a TS100.

>> No.1605565

also get special copper tip for immitation crab meat

>> No.1605727

Is there some magical math equation that would allow me to convert voltage of an alkaline battery to capacity left? I don't need mAh, just % is fine so that i know there is say 50% capacity left

>> No.1605739

Look for the thing's datasheet and find a voltage-capacity curve? If you get a voltage-time graph with constant current or constant resistance, you could convert it into power by P = V*I or P = V^2/R, then integrate the power with respect to time to get energy with respect to time, and then combine that data with the voltage data. There's software out there that can turn picture graphs into actual data points, but the whole thing would mean a fair bit of faffing about, likely in python.

So instead I'd just look at the graph that has the most similar intended lifetime, see where your voltage is, and check its time with respect to the max.
For example: http://data.energizer.com/pdfs/e91.pdf
If your expected lifetime is 10 hours, that's as long as the CDs/Games graph, so at 1V per cell you're at about 2 hours left, or 20% left. Comparatively, if you mistakenly used the 90 minute graph for the high-current digital camera, 1V would look more like you've got 33% left.

If you really wanted a theoretical equation, all I can tell you is to look into the Nernst Equations and clench your butthole for some nasty chem/math.

>> No.1605744
File: 5 KB, 548x313, AA-500mA.png [View same] [iqdb] [saucenao] [google] [report]

Take a look at discharge curves.

After 0.9V the battery is basically spent.

Enter some data points and approximate a function.
Even a linear one isn't that inaccurate:

The more you increase the polynomial degree the better it gets:


>> No.1605752

thanks for replying. I found a post by paul stoffregen saying not to draw more than 20ma continuous, max rating screencapped is twice that, so for safety i'll use a transistor or change out the resistor to 2k for some headroom.
I actually backlit the entire handwired keyboard with 1k resistors per led and it turned out nice so it's a good value. afterwards I cut down the power more at the mcu with 500 ohm to adjust the brightness.

>> No.1605755

Oh you should swap the axes and invert the capacity,
so you have a convenient function where you just have to insert the voltage and get remaining capacity

>> No.1605759

Thanks, that will do nicely. I don't really need a high level of precision, +-15% is fine, i just need a project to monitor its battery so it can alert me when it starts running out, while being able to check the rough capacity left along the way

>> No.1605764

>Ah vs V
Uh, doesn't that make less sense than using Wh? Because having Wh on the axis means you're actually checking how much energy is stored, as opposed to charge. If you're feeding a linear regulator then Ah makes more sense, but a switch-mode converter running off the cells would be far better with Wh or J.

There's also a maxiumum current draw for the entire MCU, which you must not surpass with the sum of all digital output pins' currents.

>> No.1605768

200ma I understand. the mcu draws 50ma, the 3 indicator led another 60ma at most(more like 30 ma) and the keyb matrix pins draw around 1ma each for pullups. I'm just gonna use a dev board and avoid the smt soldering.

>> No.1605802

>hot air station costs $12 from chinks
>they all have $25 shipping cost

>> No.1605805

Only the gun has free shipping tho. I wonder how hard would be to diy the brick for it

>> No.1605854

Why not buy a cheap paint-stripping hot air gun and a PID controller?

>> No.1605863

Because it is made for paint stripping?
And i doubt they can beat $3 for the gun itself with a set of nozzles.
I figured it out, the heat element in the gun is powered directly by AC which i will trigger via SSR, the fan is 24V so simple boost converter will handle that and the thermocouple will be hooked up through an op amp to an arduino mini along with the reed switch for automatic shut off and i will also toss in a potenciometer and an oled and let the arduino controll the temperature.
this will be easy as fuck and it will look great

>> No.1605884

>use arduino mega 3.3V rail to pull sensor pins high so that raspberry pi can work with them
>decide to measure said arduino 3.3V rail because I was bored
>it's 5V
What the fuck is going on and why are my raspberry pi GPIOs still working
can someone check their arduino for reference?

>> No.1605893

What do you call those displays that digital watches use which drain almost no battery?

>> No.1605894

advances ics like that have overvoltage protection, so they won't burn but it will wear them out much faster

>> No.1605895

LC Display

>> No.1605897

you mean LCD?
Those need lots of power for backlight and stuff, i am trying to find some small display which will display a value from arduino nonstop which minimum battery drain.
The digital watch-like display seems ideal, but i can't find anything like that on ali (apart for e-ink but that is expensive and not ideal for what i need)

>> No.1605899

I thought the raspberry pis didn't have that

>> No.1605901

can be many things, some sensor automatically convert output to 3v3 even with 5v input, some protocols like i2c only pull to ground so it doesn't matter what voltage the output pins are, only the pull ups for the lines

>> No.1605910

(Most) LCDs come with a reflective back so you can read it without any extra backlight when it's not completely dark.
Digital watches rely on that too, and only turn on a backlight when you press a button.

>> No.1605921
File: 99 KB, 1000x1000, HTB1ttcGeIrI8KJjy0Fhq6zfnpXaR[1].jpg [View same] [iqdb] [saucenao] [google] [report]

I see. I'm going to try this one, seems pretty wide spread in the fartduino community and you can pull a jumper to turn off the backlight

>> No.1605969
File: 34 KB, 804x495, 2019-05-06 19_40_50-EveryCircuit.png [View same] [iqdb] [saucenao] [google] [report]

why is it not working

>> No.1605977

looks like ur dumb tester has a diode in it

>> No.1605978

It does, something else doesn't because it's floating.

>> No.1606141


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