STM32 Open Source Multimeter

One of the most essential tools for anybody interested in electrical engineering is certainly a Digital Multi Meter (DMM). The problem is you really never have enough of these – there is always one more voltage or one more current that you need to measure when testing a circuit. So about a year ago I … “STM32 Open Source Multimeter”

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Seven Segment Multifunction Display

Often, when I am prototyping something on a breadboard or elsewhere, I need to see voltage levels at multiple points of the circuit. Of course you can hook up multiple multimeters, but a) I don’t have that many multimeters and b) they are usually relatively big and take a lot of space on my small … “Seven Segment Multifunction Display”

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ESP8266 ultra low power thermometer

This is another project I originally build for a ground school here in the Czech Republic. But in the end, I liked it a lot, so I build a few of these modules for myself as well. It’s basically a small ESP8266-based board with a BME280/BMP280 sensor and these features: measures temperature, humidity, pressure (BME280) … “ESP8266 ultra low power thermometer”

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Testing the range of NRF24L01+ modules

One of the biggest trends these days is making everything wireless. And sometimes it really comes in handy to have a radio module capable of transmitting data between two microcontrollers. And because I don’t know that much about radios, I have to stick to ready-made modules, like the NRF24L01. While you can get a lot … “Testing the range of NRF24L01+ modules”

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Simple camping light/torch

One of the most useful tools when camping is a flashlight. They come in a ton of different shapes – headlamps, torches, lanterns… I have a good headlight, but sometimes I want to, say, illuminate a whole tent or a room. For this a headlamp is not suitable, because it is very directional. So, from … “Simple camping light/torch”

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Arduino Universal Battery Charging Shield update

One of my most viewed projects ever (both on Instructables and Github) is my AVR Universal Battery Charger. It was also one of the very first projects I ever published, so there wasn’t a proper schematics or board layout (back then I simply didn’t care), my code was messy and the hardware had some flaws. … “Arduino Universal Battery Charging Shield update”

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3D printed charger for Yi 4K camera battery

I own an action camera – the Yi 4K – and I am very satisfied with it. However, even though it has longer battery life than a GoPro, it still runs for only ~90 minutes on a single battery. For this reason, I bought a bunch of replacement batteries from Ebay for just 6 dollars/piece! … “3D printed charger for Yi 4K camera battery”

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An interesting experiment: cooling a Cree LED on a normal FR4 PCB

Modern LEDs have enormous efficiency – up to 40 % – but this still means that if you mount a 5 W LED on a PCB it will generate up to 3.5 W of heat. In one of my recent experiments, I tried making a headlamp using a Cree XPG-BWT LED. I made a small … “An interesting experiment: cooling a Cree LED on a normal FR4 PCB”

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Trace & via current carrying capacity on PCBs from JLCPCB

If you ever designed your own printed circuit board, you might have wondered “how thick does this trace needs to be?” or “how big this via needs to be?”. As always, you can try to Google it – however, you will find a lot of conflicting information, and that is why I ordered a simple … “Trace & via current carrying capacity on PCBs from JLCPCB”

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