About

Battery Killer

This project was a test of several things:

I had seen people building joule thief circuits to use up the last remaining power from nearly dead batteries but I wanted to do something more complex as a challenge. I decided to build a custom PCB around a single AA battery holder and use it to power an ATTiny85.

I started by selecting a single cell AA holder that would provide the PCB footprint. I wanted something with through-hole pins so that my design wouldn’t have any wires that could eventually break.
The next step was designing a power supply. I knew that I needed a minimum of 1.8v to run the ATTiny85 controller so I opted for an MCP1640T boost regulator. It’s capable of running on well below 1.0v input and has an adjustable output from 2.0 to 5.5v which was perfect for my application.

PCB Front

PCB Back
The notch in the PCB is actually to allow clearance for the orientation pin on the battery holder. I only needed a few boards so went with OSH Park for fabrication.
The finished board.
It's alive! I included the button so that I could program multiple modes for the LED. I just have a few basic options so far: PWM fade, blink, solid on, and off.
Inline serial programming using pogo pins to connect to my Sparkfun Tiny AVR Programmer. This setup gives me an easy way to update the code in just a few minutes.