Small +5 volt 1 Amp Li-Ion Power Supply
![Original and hacked boards with battery and charger](psu_hack_files/stacks-image-aa77284.png)
The original circuit, hacked circuit and battery and charger
This is another project born of necessity. A new costume with a bunch of LEDs needed a +5 volt power supply. After burning out a Sparkfun boost converter module I turned to hacking one of my own circuit designs. For a series of gifts I had designed a small LED controller that drove commonly available +12 volt flexible LED arrays. It used a Linear Technology LT1935 boost converter IC to step the voltage from a Li-Ion CR123A cell up to 12 volts. I had some spare boards and parts laying around so I figured I could just repurpose the converter circuit to generate +5 volts with a change in the feedback circuit. Of course the empty pads where the PIC 16F1825 microcontroller went was too inviting and I ended up writing some code to display the current battery level and provide an automatic low-voltage shutdown so the Li-Ion battery wouldn't be damaged. This circuit can supply up to about an amp of power.
![Close-up of hacked board](psu_hack_files/stacks-image-e175128-300x218.png)
![Pressing button on hacked board to show battery level](psu_hack_files/stacks-image-a5d7f8b-300x224.png)