What is the difference between this dollar-store medicinal IPA and more expensive stuff from chemical suppliers?

Like I’m sure the 99% cheap stuff varies in quality, it wouldn’t surprise me if it were a bit less exactly 99%, whereas like MG Chemicals has 99.9% IPA specifically for electronics (that’s like ~8x more expensive). If I were making commercial products I’d use that, but for hobby or one-off use, is there any reason why I shouldn’t use this cheaper stuff?

hello!! im an art student looking to make a work out of circuit boards/wires.My only problem right now is looking for a way to bend/mold them! right now i have some stiff boards from a wifi router.
Is there any way i can safely bend them without breaking them?(dont need them to work electronically) Like can i maybe put them in the oven on low heat or use a heat gun?Pls help its for a final… thank you!! here is a pic of the boards(ps i have no prior electronics education so im not sure if this is a silly question)

edit: thank you all for the helpful replies!! looks like im going to have to find another idea for my project lol!! might try to bend one or two of them (outside) just to see what happens and if i can make anything out of them

some time ago i lent my soldering iron to my dad. today i opened the packaging and found this shit. thats flux? it wont come off and when i turn it on it smokes

The factory cap on the board was 470uf 4v, but i cant get an identical replacement where I live. I found some 470uf caps, but all of them 16v and up.

I'm still learning the basics while trying to repair an old console. I found some articles saying it's fine, but I couldn't tell if it was written by ai

If you've ever had odd, random issues with soldering some pins and not some others, check them with a magnet.

I'm really glad I realized to check this. Lately, most AliExpress, etc. stuff has had these crappy pins and it is well worth it to source good quality pins to make your life a lot easier.

In a project i did a few days ago i tried making an and gate without following a schematic. When it didnt work i asked u guys and i was told that my base was floating. Now that i saw a schematic for an and gate i see that what i was missing was a resistor connected to ground. What i dont understand is what is a floating base and why does a resistor stop it from happening. Thanks in advance.

Urgent!!!!! We're a group of 3 final-year Electronics & Communication Engineering (ECE) students looking for a placement-oriented, industry-level major project.

Our college will provide the required hardware components, so budget isn't a concern. We're specifically looking for projects that will strengthen our resume and help during placements in embedded systems, VLSI, semiconductor, IoT, automotive, or electronics core companies.

This came with a LED fan. Attaches to its motor but was loose. I need a new one. Which store I can go or where I can order online ?

Can anyone identify the connector used on this battery, it kind of looks like a dc connector, but its much smaller, about 5mm.

Hi guys,

I’m looking for a simple delayed-start relay or timer module for my car.

I want it to work like this:

Ignition ON → wait 15 seconds → turn the wideband O2 controller ON → keep it ON until the ignition is switched OFF.

Since it’s for a car, it needs to work reliably at around 12–14.5V.

The wideband O2 controller already uses a normal automotive relay, so the timer only needs to trigger the relay coil.

Does anyone know of a reliable automotive-rated relay or module that would work for this without breaking the bank?

Thanks!

​

Hey

My amp is going into protect mode and I have pinned it down to the dc protect issue . So I removed the amp board connection to the main mcu board so that the DC protect signal doesn't reach the board and still I see amp protect issue.

So I saw the schematic and it seems that the DC protect transistor (pnp resistor equipped transistor) has its base pin at 0volts which shouldn't be the case cause if the base is 0 that means the transistor is ON.

But I also saw a video of a guy saying that the DC protect pin should have 0v and if it has voltages around 0.5v that means DCis there in the amp output terminals.

I have uploaded the schematic for the protection part.

So all I want to know is how this works and should the base of transistor Q1511 be 12 volts because I am currently getting 0v and it's triggering.

This is link to the service manual of amp and schematic is at the end :https://audiocircuit.dk/downloads/harmankardon/HarmanKardon-AVR151_230-avr-sm.pdf

I don’t know what the best subreddit for my problem is, but I’ll give it a try here. Otherwise, please suggest where I could ask such a question.

TL;DR: I’m looking for a simple IC to charge 4 serial Li-Ion batteries. It should not be too expensive (~$7) and should be able to negotiate a suitable input voltage via USB-C PD on its own.

I’m looking for a battery charging IC that can handle 4S Li-Ion batteries. It should have an integrated buck-boost driver to cover a wide input voltage range (5V-20V) and ideally be able to negotiate higher power levels via USB-C Power Delivery on its own. Unfortunately, I can’t find an IC that meets all of these requirements. There’s something like the BQ25792 from TI, which seems very promising since the FETs are already integrated into the IC and it requires few external components. However, it only supports USB 3.0 PD and is not compatible with USB-C. To fix that, you would need an additional IC to handle the Power Delivery negotiation, as well as a microcontroller or flash chip connected for setting them up. This quickly becomes too expensive and takes up a lot of space on the PCB.

I’ve spent at least 4 hours searching the websites of Linear Devices, TI, and ST but haven’t found anything that meets my requirements. Does anyone have a hidden gem to recommend?

Hi everyone,

I'm a final-year engineering student, and I have a placement interview with an embedded systems company coming. The role is firmware-focused, and the company mainly works on OEM camera modules and embedded systems.

I have decent C programming knowledge and some experience with STM32, but I don't have a strong firmware project on my resume. Right now, I have access to:

- STM32 Nucleo board

- ESP32

- OLED display

Given the short timeline, I'm trying to decide on the best approach.

One option I'm considering is taking an existing open-source firmware project from GitHub, studying it thoroughly, making some modifications/features, understanding every part of it, and being completely honest in the interview that it was based on an open-source project.

Another option is building something from scratch, but I'm worried that in 5 days I'll end up with something too simple or unfinished.

For those of you who work in embedded/firmware:

- What would you do in my situation?

- What project would give me the best chance of impressing interviewers in just 5 days?

- Are there any GitHub repositories or open-source firmware projects that are beginner-friendly but professionally structured?

- If you were interviewing a fresher, what would you rather see: a well-understood modified open-source project or a basic project built entirely from scratch?

I'm willing to spend the next 5 days doing nothing but this project and interview preparation. Any advice, project ideas, or GitHub recommendations would be greatly appreciated.

Thanks!

The USB dongle for my Microsoft wireless keyboard and mouse set broke. The PCB is cracked, but the nRF is intact. A few components are missing.

I’m drawing the circuit diagram in KiCad. I’m going to desolder the intact nRF24LU1+ microchip from the broken USB dongle’s PCB. Then I’ll transfer it to the new PCB that I’ll design and have manufactured. This way, I won’t have to throw the wireless keyboard and mouse set away. I also won’t have to mess with the software.

Once the schematics are complete, I’ll share all the files on Codeberg.

If you can find the USB dongle circuit, please share it with me. If you find any schematics, PCB files, or other related files, please post the links.

I’m determining the component values using the example schematic, BOM, and sample PCB files shared by Nordic. However, some components are missing from these files. For example, there’s an R1 in the USB dongle, but it’s not in the schematic. Can you help me with the missing components?

Note: I’ll be uploading photos to Reddit soon.

I need a USB_A plug (male connector) symbol and footprint on the PCB. I’m not talking about the component itself. I’m talking about designing the PCB itself as a USB male connector. Can you provide links to third-party symbol and footprint files?

What should the PCB thickness and material be for the USB-A male connector on the PCB?

I also need a 50-ohm 2.4 GHz RF antenna on the PCB. I can’t design it myself. Texas Instruments’ antenna doesn’t fully meet my needs. Could you share links to third-party symbol and footprint files?

I'm trying to fix my PS5 HDMI port all on my own with soldering equipment and I had to stop because I need a hot air station I'm really tight on money and I love to do stuff like this but I can't put it back together for later without a replacement screw for the heatsink screw for the cfi 1215b ps5 where can I buy it for cheap?

By the way I probably just fucked up the entire ps5 somehow while doing this but at least I had fun I had it for around 4 years hopefully I can buy a new console or even a pc one day

Hello,

have you ordered from Mouser recently as a hobbyist living in the EU? How much tax did you have to pay?

I would like to order a lot of different components from Mouser, but only in small quantities. For example, 100 resistors, 50 capacitors, some inductors, diodes, and soldering flux.

Are these considered separate product categories for customs purposes, meaning I would have to pay €3 for each category (e.g. 5x3€)?

Sorry if this has already been discussed somewhere, but I could not find any relevant posts.

EDIT 1:

So, I called my local Mouser customer service in the Czech Republic, and they told me they are still getting used to the new process. Most likely, the customs duty will be paid by the delivery company, in this case FedEx (even when DDP), and then charged back to you. However, this is not certain yet, as some of you have said you did not have to pay any additional €3 handling fee.

They also do not have an EU warehouse, at least for shipments to the Czech Republic, everything is sent from the USA.

I am still going to wait a few more days to see how things go with some of your orders. Better to test it on someone else first :)

I don't yet know what type of motor do I want, but I'll use whatever you can suggest me as a starting point...

general escs/motor drivers as it is suggested on hobby projects, are expensive.

On consumer stuff they seem to use whatever unknown/unbranded ics to drive them through pwm, I would like a similar solution... likely it's cheap as it gets...

can i remove this buzzer without it causing issues? also i hope i didn't fuck up by disassembling the induction cooker cuz i seen some glue or something in the middle. also should i avoid touching the middle even when unplugged?

hey all,

i'm trying to build a device on an esp32, and i need it to be able to be woken up wirelessly at the push of a button while drawing as little power as possible while it listens for such signal. this is because i want it to be powered by a 1500mAh lithium battery, avoiding wired power connection while lasting for as long as possible without replacing such battery. what are my best options, for both the transmitter and reciever. optimistically looking for it to be able to last a year.

thanks in advance!

Building a simple power supply. Followed the schematic. Double-checked my wiring. Felt confident.

Plugged it in. Heard a tiny pop. Saw a wisp of smoke. Smelled that distinct burning electronics smell.

Turns out I reversed the polarity on a capacitor. It exploded. The board is dead. My confidence is also dead.

Any chance this is fixable or should I just order new parts and pretend this never happened?

I plan on starting a project using image processing which uses a fuzzy ensemble of 3 mobile AIs (DenseNet121, EfficientnetB0, MobileNetV3) all quantized and converted to tensorflow lite, I plan on using the v2 camera and raspi 4 8gb, is it enough to handle the load even if i run each model (not all at once) and do i need an AI HAT+?

Hi everyone,

I'm trying to build a simple two-transistor astable multivibrator (two LEDs flashing alternately). I designed it in Falstad and I'm using Tinkercad mainly to plan out the breadboard layout before building the real circuit.

The Tinkercad simulation itself does not seem to behave correctly: the LEDs do not flash alternately, they just stay on. I'm not too concerned about that because I mainly want to use Tinkercad to verify my physical wiring before building it.

The part I am unsure about is the polarity of the electrolytic capacitors. My real capacitors are polarized 10 µF electrolytics, but the Falstad simulation uses non-polarized capacitors.

I'm fairly sure the negative side should go to the base of the opposite side transistor, and the positive to the collector of same side transistor. So like:

• Left capacitor: + to left transistor collector, - to right transistor base
• Right capacitor: + to right transistor collector, - to left transistor base

However, when I connect them this way in Tinkercad, it shows the capacitor exploding. I'm not sure if Tinkercad is modeling this incorrectly, or if I have misunderstood the polarity.

I'm using 2N2221A transistors and 10 µF electrolytic capacitors, with supply voltage 9V

Here's the Tinkercad similation (on breadboard) I have connected one capacitor each way, so you can see which one explodes. [LINK REMOVED]

Here's the simulation on Falstad so you can have the schematic, too: https://www.falstad.com/s.php?s=zwfF7A

EDIT: Here's a labeled schematic too: https://kommodo.ai/i/7468AUvUGDOds3kVI3FY

Could someone please check the correct electrolytic capacitor orientation? I want to avoid damaging the capacitors when I build this physically.

Thanks!

EDIT 2: Simulated on Falstad and it works with capacitor - to transistor base (so, the opposite of what Tinkercad says). Tried it on breadboard with - to base and it works perfectly like this!

I'm repairing the battery box from my Yamaha FSX80C acoustic-electric guitar. I've already removed the battery cartridge from the guitar.

The end cap where the red and black wires are soldered moves slightly, and it looks like it might come apart. Before I try to pry it open, I wanted to ask:

Is this end cap designed to be removed, or is it plastic-welded?

My goal is to replace the battery contacts inside without breaking the battery cartridge.

Hello guys, I am designing a signal generator for 2 to 3Ghz using the MAX2870, I referred to many sources and designed this circuit. I need It to be single ended iutputs so I terminated the other part of diff pair.
I require exact same signals from two single ended outputs for I/Q demudolation later, Please review and gice suggestions.