electronics – Andrew Nelson

Repaired Presonus HP4 v1 Headphone/Monitor Amp

April 11, 2014 andrew

My very useful Presonus HP4 v1 headphone amp fried last Fall. I found another on eBay for not too much, but I hung onto the old one. Turns out they’re full of this quad amp IC, MC33079P, and one on the input stage failed. The chip is obsolete, but I replaced it with an MC33079PG that seems to be the same. Or at least compatible. The hardest part was un-soldering a 14-pin IC without destroying the PC board. I added…

Shrinkify Arduino Project – LED Pumpkin Candle

October 30, 2013 andrew

I just successfully completed my first “shrinkified” project – a flickering LED pumpkin candle. I built the project on an Arduino Uno and then using a tutorial from the High-Low Tech group at MIT, I flashed a ATtiny85 with the code and freed up my Arduino. The LED candle flickers randomly and occasionally glares angry red for a few seconds before returning to flickering. The LEDs are tri-color and flickering is accomplished changing the green color value (against steady red)…