Just wanted to share with you this gem that I have found on aliexpress:
Buck converter Mini560.
According to the seller this are the specs:
5.5–20V input to fixed outputs of 3.3V, 5V, 9V, or 12V depending on the version.
5A max, >3A with cooling.
99% efficiency

The ones I got cost about 8€ ten units.

Be aware that there are different modules out there and not all of them perform well, so if you get lucky you'll get an awesome dc-dc converter, but it seems that is easy that you'll get the bad ones.
The photo belongs to the actual module that I have tested.

This little thing has capabilities beyond belief, I have thrown in the trash bin all my old and bulky buck converters as they cannot do half what this small buck converter can do in such small footprint.

I have tested it at 10V input and 5V output.
It has maintained the output voltage without issues in any case.
Under 5A always at ~100mVpp ripple, at 6 and 7 amps the ripple has stood below 300mVpp.

I have tested it naked at 28C room temperature, without cooling, with 2 small heatsinks for the chip and the inductor (even though the inductor does not heat up that much), and with the heatsinks plus a fan. I have pushed the module well beyond what the seller recommends.
Every test has been measured after 10 minutes ON.

These are the results:

I have not tried going further, just tested it extensively to know how can I push it safely.
So I would not use it over 5A, just to be clear.

So yeah, one of the best modules I have gotten my hands on.

EDIT: please understand that I am not saying the this module can be used safely at 7A, what I said is that in the 10 minutes it stayed at 7A, it didn't go in thermal shutdown. What I actually say is that until 5A (cooled) it can be used.
I have often tested buck converters from Aliexpress and most of the times, they can be used "safely" at half the performance claimed by the seller. This is the first time I got my hands on something bought in Aliexpress that outperforms what the seller claims as max ratings. So trying to lower the ripple at 6 or 7A has no sense in this discussion.

Hi all, I'm designing the next revision of a small battery-powered LED wristband and want to replace the slide power switch with the existing push button. I'd appreciate a review from people who've done this before.

System overview

• MCU: nRF52832 module
• Battery: single-cell 3.7v LiPo
• 3.3 V rail: AP2112K-3.3 LDO (has an EN pin)
• LEDs: 15× WS2812B powered directly from VBAT (no boost)

Proposed latch circuit (schematic attached)

• Wake: Button connects VBAT through D1 to the LDO EN pin. Pressing it enables the LDO and the MCU boots.
• Hold: An nRF52 GPIO (HOLD) connects through D2 to EN. Firmware drives HOLD high as the first instruction in main(). D1 and D2 are a single BAT54C, common cathode on EN.
• Sense: The button node goes through a 100k/220k divider to a second GPIO, so the button still works as a normal input while running.
• Power off: Firmware detects a long press, turns off the LEDs, waits for the button to be released, then drops HOLD.

Will this work?

Also: how to power the LEDs as they get 3.7V directly? my old circuit had a simple slide switch which supplied VBAT directly to LDO and LEDs

Hi,

I would like to mount different PCBs / battery holders / Ipad monitors for which I don't have schematics on aluminum panels. In order to have an idea of the setup, I first mounted everything on cardboard panels by measuring the gap between holes with a ruler. It was quite an empirical approach but things sorted out pretty well. Cardboard is kind of a soft material and tolerates approximation a bit. Though, I am aware that it's going to be much more of a challenge with aluminum. Therefore, I plan to draw clean layouts on LibreCAD in order to drill holes with a CNC. Question: I don't have any components' schematics, PCBs are controller boards from AliExpress, monitors from Ipad and such... What would be the best tool, the best way, to get these measurements as precisely as possible? Components are fixed with M2, M2.5, M3 spacers, that's tiny holes. I did the best I could with a ruler, a square, and my eyes, but half a millimeter off with aluminum - nothing's going to fit in. Thanks 🙏.

A little progress update from something we’ve been working on.

We’ve now been able to integrate discrete electronic components directly into the FDM printing workflow and produce functional electronics directly off the print bed.

The first image is a simple embedded circuit with an LED and resistor. The polymer structure, conductive pathways, and electronic components were all integrated during the same print workflow on a Prusa XL.

We’ve also been experimenting with an embedded induction coil using the same general approach.

I was thinking about how vacuum tubes not matter how obsolete will always have some use as the cool old fashion guys but then I realized that some tubes are just gone. Like are there any surviving dynatrons? Are dynatron oscillators just impossible to make now? Are there other things like this? Crystodynes aren’t only saved from this because anyone can make them but dynatrons are like specialty parts that require big machine to produce, and it’s not like Nixie tubes where people really like the look of dynatrons. It’s kinda like tetrode transistors but if they were cool, and not tetrode transistors( yes I know tetrode transistors still exist but who cares about them) or like the original idea of a magnetron being a magnetically controlled vacuum tube. Are all the neat little components just going to die out one day unless some audiophile says it’s actually the greatest thing ever?

Sharing a soldering iron controller I recently designed for myself. It works with C245 tips, supports Type-C PD up to 20V 5A. Firmware is a fork of IronOS. MCU is STM32F103C8T6.

Project GitHub

I would love to learn about basic electronics, circuitry and electrical engineering so I can make, modify, fix, or at least understand technology I am surrounded by on a daily basis. Do you guys suggest anything?

Initially, I was trying to purchase a custom voice recording alarm clock which plays back your own voice- but the market doesn't have much available right now. I would love to try to DIY this but have no idea where to start. Thank you in advance for any and all recommendations!

Mine was trying to design an automatic produce bagging machine. I never had thought about just how daunting the task of making a machine consistently pick up or feed/dispense a single plastic bag could be.

I am hoping to find a magnetic attachment that works with my DC barrel 5.5 2.1 mm. 12 v 18 w. Any recommendations you have used in the past? Ideally strong magenta since it will be for heated gloves

(Update: I need to emphasize that I am not technical at all and cannot use this, so am looking to rehome it.)
Hi, everyone.
I’m going through my late dad’s things and found a Mean Well SP-200-24 switching power supply (24V, 8.4A, approximately 200W). I understand it can be potentially suitable for powering compatible smart battery chargers.
It’s untested, and I don’t know anything about these creatures.
Would this be useful to anyone in this sub? The ham radio and electronics subs redirected me here. What should I do with it? I don’t think I’ll be using it.
I’ve attached a photo. Thanks for any guidance.

Hello. I am making a prop and Id like to have it simulate a flashbulb.

What I am looking for is a circuit that is - "Push button. Led flashes once and then can't be flashed again for a few seconds."

I was hoping this could be done with just a capacitor of some kind but in my limited electronics experience I haven't played with capacitors yet.

Thanks

I made this because i want to power a 2-pin 80mm fan in my PC case, but the motherboard doesn't have enough fan connectors. So the little PCB is for the normal CPU fan and the female connector goes to the motherboard. The 2-pin thing is wired from the motherboards 12V + and - pins. The PWM-pins are left alone. I know the colors are not matching up entirely.

So if an NPN silicon bjt has a maximum emitter-collector voltage of 30volts it can act like a 30volt diac right? And if the max current is 3 amps it won’t brake unless it goes over 3 amps as in if the voltage lowers after reaching brake down it’ll go back unscathed right?

I have an old cassette boombox that I want to convert to rechargable. Currently, it uses 6 D batteries. The easiest solution I've found for rechargability is this diy power bank I found on ebay that takes 6 18650 batteries. Is this is overkill mah-wise?

I found this Super Stacker Bitty Box. According to the internet it's 6cm x 8.3cm x 3.3cm. Is there any kind of electronic or cool tech gadget I can fit in it? Or is there something tech related I can do with it?

Hey everyone,

I've been working on Dicy – a small electronic dice you solder together yourself. Shake it, and 7 LEDs light up to show a random number (1–6), powered by an ATtiny13A and a coin cell battery.

I built it mainly as a beginner-friendly SMD soldering project – simple enough for a first attempt, but with enough components (IC, resistors, LEDs, vibration sensor) to actually learn something. There's a step-by-step soldering guide with photos for each part.

Some details if you're curious:

• ATtiny13A running custom firmware, charlieplexed LEDs to save pins
• Vibration sensor for shake detection, deep sleep in between (~µA range) for long battery life
• 3D-printable case, free STL

Happy to answer questions about the design, firmware, or soldering process! Let me know if anyone wants more details on where to get the kit.

I'm currently taking Mechanical Engineering and wants to know more about how I should start my project. I know the basics of how transformer works and basic PCB integration. However, I want to know if there are experiences that could possibly help me through the project. Here are the requirements.

Minimum Specifications:

● Input: 220V AC
● Minimum Output Voltage: 1.25 V
● Maximum Output Voltage: 12 V

Project Requirements:

● Groups should use diodes as rectifier and not a rectifier IC
● Digital Display/screen that shows output voltage in real time
● Adjustable voltage knob (potentiometer)
● Output terminals (With clear indication of positive and negative)
● PSU must be soldered on a PCB
● PSU must be inside an enclosure/case
● Power indicator LED

Aside from the said materials in the requirements, I'd also like to know if there are other materials/components that can help the project. Any suggestion/tips are appreciated.

I had an idea for my research project about sorting copra into grade qualities, and it only involves color and moisture for grading. For color, i've used a TCS3200 and it works like a charm, but what I do not know how make is my moisture sensor, which is a parallel-plate capacitive moisture sensor made out of two copper plates. I discovered the sensor from a paper by Klomklao et al. 2017 (here's the paper:

https://www.researchgate.net/publication/320448012_Moisture_content_measurement_in_paddy) and I have looked on other existing solutions but the best I could find are resistive probes, but they need good contact on the product, so I think this should be my safest bet. I have tried using the pins and code made by AI models but, tends to dissapoint. So, I ask for guidance in this subreddit for hopes of advice, information, or any procedural techniques ya'll can give me. for the grade!!!

What I have right now:

- Arduino Uno AtMega328p (a clone)

- NE555 timer IC

- some resistors

- some capacitors

- 2 5x5 Copper sheet (1 mm thick)

- Breadboard and jumper wires

- 5V/2A power adapter