Category Archives: Electronics

My First Crystal Radio

As I was trying to organize things a bit in my “office”, I happened to unearth a bit of nostalgia. This is my first crystal radio. I built this thing after reading about it in some old book. It’s probably … Continue reading

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Retro LED Displays

I recently found some HP 5082-7433 LED bubble display modules on eBay. These are three digit, 7 segment displays with decimal points. The “bubble” is a magnifying lens molded into the epoxy package. I ended up finding a datasheet (warning, … Continue reading

Posted in Arduino, Electronics | 3 Comments

Frankenstein’s Lawnmower

I have a battery powered lawnmower. It’s powered by a 17Ah 24V battery which lasted four seasons before it just wouldn’t finish the lawn. The replacement battery started giving me trouble by the end of the first season. It was … Continue reading

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Constant Current Dummy Load

This is a constant current dummy load I put together recently. It was inspired by the EEVblog version. Mine is simplified, using only one op-amp. It also requires a multimeter to monitor the current. I used parts I had on … Continue reading

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Interfacing the PS/2 Keyboard

As an exercise, and to help me learn about the protocol, I’ve set up my trusty Arduino to read scancodes from a PS/2 keyboard. The protocol is fairly simple. The keyboard uses four pins in the connector whether it is … Continue reading

Posted in Arduino | 2 Comments