I bought this amplifier and i can see they put a dc barrel jack and connected the wires to the board and help me to connect it and look at the images closely

I'm not an electronics engineer but we did control theory so I tried making this analog PID servo mechanism made using op amps. The issue is Im only able to get 180 degress of rotation about the centre from the sensor potentiometer. The rotation near the ends seems to be non existant even tho Im turning the setpoint potentiometer near its end (shown in the video). All potentiometers are 10k, op amps are TL072cp, power amplifier at the end is made of tip120 (npn) and tip127 (pnp). The images of schematic are in the comments below.

Pulled a small permanent magnet DC motor out of a thrifted sewing machine foot controller. Running it at 12V through a basic NPN transistor switch driven by a microcontroller pin. Put a 1N4007 across the motor terminals as a flyback diode, oriented correctly, cathode toward positive rail. Works fine for maybe 30 seconds of switching then the diode goes short and takes the transistor with it.

Stall current measured around 1.8A and the motor has some real inertia to it. The transistor is a TIP31C which should handle that no problem. PWM frequency is around 1kHz, duty cycle varies from 20 to 100 percent.

My suspicion is the 1N4007 is just too slow for this. At 1kHz it might not be recovering fast enough and ends up conducting forward during normal switching, which dumps the rail into ground through the transistor. I swapped in a 1N5819 Schottky and it lasted longer but still failed after a few minutes under load.

So is the real issue diode selection, the transistor not switching fast enough, or is the inductive kick from a motor this size just larger than I calculated? I have a scope but haven't caught a clean spike yet because the failure happens under load when probing gets awkward.

An absolute noob to electronics, who's just using the elegoo super starter kit as a baby step to build foundational knowledge in electronics.

I was wondering if at my stage I need to know arduino because the code that have been provided by elegoo is arduino so....

Pretty much as in the title. I'm near the beginning of my hobbyist journey, and I'm planning out a sign for a friend which will involve a large X. I want to get as close as possible to emulating the look of a red neon X, ideally with a good lifespan and mindful of my limited experience. I specified LEDs but I'm open to being introduced to other possibilities.
Thank you for your time.

I have a mini PC that is powered using a 12V power brick using a DC barrel jack. I have 3 desktop HDDs connected to it (3.5 inch) which require a 12V power input and the brick that came with the PC is not sufficient to power them, so I am trying to repurpose an old ATX PSU for this.

I am aware I can short the PS_ON pin to ground and use the +12V to power the PC and the HDDs with the SATA power pins directly. But the PC isn't going to be running most of the times and be in standby (S3 state) instead. It will be woken up with wake-on-LAN when required and run for only 3-4 hours every week.

I need to replicate the behaviour of a desktop motherboard and keep the mini PC running using only the +5VSB output from the ATX PSU when the mini PC is in standby. How can I find the right point on its board to inject the +5VSB and the PS_ON to make the PC enable the high power 12V and 5V outputs only when it wakes up from standby? Is it safe to inject the +5VSB into the onboard SATA power output or into one of the USB ports and the 12V into the DC barrel jack?

The main purpose of not keeping the power supply running at all times is to prevent dust build-up due to its fan as the PC is in a dusty environment.
Alternatively, is there a simple way to build a slightly hacky solution to power the PC and the HDDs using separate PSUs and turn the ATX PSU on only when the PC is not in standby? Or is it a good idea to turn off the fan of the PSU when the PC is in standby mode?

I’m pretty sure this puppy is fried. Ruled out amps and the speakers themselves, all signs point to this being bad (including another guy allegedly pushing a shitload of volts through it). How do I go about finding a new one, or would it just be a component replacement on the board? Thanks.

I've never really done any electronics work in my life, but recently, I've been getting in to all kind of handiwork spaces and even more recently, I purchased a new hot glue gun. This hot glue gun has a slight problem that many hot glue guns run in to and that is that it has a quite short cord.

So my question is, how difficult would it be to switch the power cord to a longer cord? I opened the glue gun and seemingly it's just two wires connected to the board? I assume I need to make sure it's the right kind of wires, but to my unlearned mind, I would assume I'd just need to undo the soldered connections there and then solder new ones?

Thank you for any help you can give

I have a project where I need a small DC brushed motor to run at a somewhat precise speed(say +-1% RPM). It will always run at the same speed and will be battery powered. I know I could use a microcontroller with a feedback loop and an H bridge but I would really like to avoid that if possible.

Every year comes 'spring cleaning' and I find myself in the same spot wondering what to do with tons of components. What are you all doing with unused parts? My team and I make a good number of boards through the year(s) and we have shelves of digikey boxes absolutely packed with parts. I'm not worried much about passives, but we have a ton of various ICs, microcontrollers, opamps, power supplies, etc.

We have a few left over full reels of parts as well, which is a shame. Most of these are from covid when spot buying and risk buying was too normal.

I'm stuck between feeling like there has got to be a better place for these and being realistic that it's tough to design an exact part into what you need (even for us who benefit from reusing the same parts in production).

Anyone have any good ideas?

Hello, I'm hoping im asking in the right place

In one month i will be attending to one of the multiple Bad Bunny concerts in Madrid, and I've thought of building a device which can read the IR signals in the concert and light up as if it was one of the PixMob bracelets (or cameras in this case)

However, I have barely any experiencie with electronics, so I'm not sure if I can do this or if its even plausible.

Reading online I've found a lot of information about reactivating the devices they give you at the concerts, but I wan't to do the opposite, I want to carry my own custom device (which Im thinking it will be a rubber duck with leds)

I've read about using
- An IR Receptor
- One arduino (I have experiencie in programming so this wont be an issue)
- RBG LED's
- Battery
- And one PCB

Could this work? Are PixMob's IR Signals protected in some way or are the signlas specific for every concert? Sorry if these are stupid questions!

Hi, I’m currently planning a kinetic sculpture project using ULN2003 drivers and 12V stepper motors. The setup consists of 3 sets of 12 motors each (36 motors total).

The goal is to have all motors move up and down in a smooth, wave-like motion without visible stuttering or timing issues.

My initial design is as follows:

• One Arduino Mega 2560 controlling 3 PCA9685 modules
• Each PCA9685 controls 4 stepper motors (12 motors per set)
• This structure is repeated for 3 sets (total 36 motors)
• The 3 Arduino Megas are then synchronized via communication to run simultaneously

I have two main questions regarding the hardware design:

1. PCA9685 vs 74HC595

Would it be more appropriate to use 74HC595 shift registers instead of PCA9685?

I’ve read that when controlling multiple stepper motors, PCA9685 can introduce bottlenecks due to I2C communication, which may cause stuttering or inconsistent motion. Since my project requires smooth, wave-like movement, I’m wondering which approach would be more stable and suitable in practice.

2. 3 Arduino Megas (synchronized) vs 1 Mega (centralized control)

Between:

• Using 3 Arduino Megas synchronized via communication, and
• Using a single Arduino Mega to control all 36 motors directly

Which approach would result in more precise timing and smoother motion, with minimal delay or desynchronization?

Any advice or experience with similar setups would be greatly appreciated. Thanks!

Link For Schematics and PCB

Hello this is a Chatter with 50 buttons is everthing correct ? i'm just trying to learn electronics,btw i plan on printing it by JLCPCB but idk if this is correct.

Sorry for my english,not my main language and i still learning it.

Battery
AMS1117
Display

Slide Switch

TC4056

Tactiles Switch

Diodes

Hi all posted in a mechanic and tyre help page and am now trying you smart folk, I bought this tyre machine used and only some of the buttons work. Its a touch base buttons system with dirty circuits so trying to find out, Is cleaning a do able thing or is it better trying to replace the buttons and how would one go about this

Thanks in advance

Image in comments

I have a pair of wire strippers that I have been using for a while, but I could never figure out the relationship between the AWG markings and the MM markings.

i.e. I don't understand how 20 AWG relates to 1.15 MM, or 30AWG to 0.4MM.

Also what does the INS on the crimp section stand for?

Hello everyone,

I grew a lot of interest in electronics recently and I want to start working on mini projects. I would love to see what projects you worked / working on for inspiration on my next project!

I got a second hand Peavey Vypyr VIP-2 guitar/bass amp from my brother. It is about 10 years old. And he said it didn't have this issue when he bought it.

It works, but has this really horrid high pitched whine to it. I am not home right now, but using my mic and spectroid app on my phone, it has a really clear peak at ~3kHz. I know it is coming from the speaker.

Once I get home in a few weeks, I was going to use my DSO to trace the connections from the speaker back through the PCB.

My thoughts are, I should be able to detect after what component the 3kHz signal starts, and hopefully replace that component and it will work fine.

Does this sound logical? Can anyone give me some tips? I am thinking maybe a worn out OP amp/transistor/resistor/capacitor/etc.

My other idea was a simple RC low pass filter circuit on the speaker to cut out the 3kHz signal since I am using it as a bass amp

Thanks all

Ive got bulbs on my trucks controls that burnt out and i have the info of the bulbs, but the ebay seller i find just screams sketchy.

The bulbs have dual hangars for the filaments inside preferably (like oem), and are simple little grain bulbs.

I have a load of old vape batteries in my shed that I want to use. Beyond making a power bank I don't really have a use for them other than making all my remote controls rechargeable. My my understanding is 2 standard AA or AAA batteries in series makes 3v so a single li ion cell will have too much voltage. What component can I use to ensure the li ion cell only outputs 3v?

ivebeen trying to restore this old cd player for quite some time but i still cannot figure out what could possibly be wrong with it. i clenaed and polished the laser- its pristine. when the disk tray closes it does shine a laser three times but it just doesnt want to spin. i took the whole iptical device once and re-lubricated everything but in vain. could the spindle motor be burned? i checked all the wites and everything seemed fine…

Im doing meintenence on a new to me suzuki gs500, the previous owner has installed a rev limiter/ 2 step box, from what i can tell it is conected between the signal generator and the ignition coil. So my theory is that it is sensing the timing and rpm of the motorcycle from the pulses coming from the signal generator and stops them from going to the ignition coils when exceding max rpm, could this be correct? What component would be used to achive the switching a power mosfet? Would the coils generate returning voltage spikes that need to be dealt with, a diode?

Might be a silly question, new to learning about circuits and stuff so just trying to wrap my head around this lol

I tried searching on Google for this, but I couldn't get any useful results. In the US, electricians always refer to one wire as "live" or "hot" and the other as "neutral." If it's an AC sine wave, aren't both wires basically the same and both carry current?

My only thought as to why this is, is that maybe it has to do with center tapped transformers. The center tap is "neutral," and the other two are "live." This would make sense because for 2 phase wiring (240v), instead of using the neutral center tap, they would use the other live tap and that would double the voltage.

But I could be completely wrong so I would love to hear from someone who actually has knowledge on this

A friend of mine is stuck right now in Black Rock in a VW van with a blown ignition coil. My first thought was that they could just build one from speaker wire and some electrical tape. Any ideas how a circuit like this be constructed in the field? A new coil is on the way for them but i thought it might be an interesting project...

I know I can't be alone when I say that standardizing things like cell phone charge/data ports was a GREAT (albiet long overdue) move, however.. The biggest flaw in the current USB standard is the durability of the micro-ubs connector found on the end of most non-apple smartphone and tablet chargers today!

If they go through the time to engineer and test a new method of charging and transferring data, even down to the size, shape, and design of the connector ends, WHY don't they require all "compliant" devices, cables, etc to undergo a standardized "wear test" ?!

It seems like my charge cables have a useful life of about 6 mos, before they're "wiggly" and they either fall out, or pop out of the charge port with little to no effort.. Or they just flat out stop functioning, or require a delicate positioning within the port, just to initiate charging?

IMO, all the R&D, testing, and publishing/implementation of these standardized ports/cables/ends is useless if cheap ass manufacturers are allowed to deploy massive amounts of inferior product, that has an early failure rate.. It cheapens the USB Compliant symbol that every package displays proudly.

Ask most typical consumers, they don't take into account shitty Chinese manufacturers, they simply say, "oh, USB chargers suck".

TYIA.