In anticipation of my Raspberry Pi arriving I have created a LiPo (Lithium Polymer) to Micro USB adapter. This adapter converts the power from a 2s – 4s LiPo to a regular 5v. This is then outputted through a Micro USB to be plugged into a Raspberry Pi board. I will be using this to power the Pi when I use it as a ground station for my Arducopter (Which will be a whole new Instructable).
Unfortunately due to the frustration of my PCB etching attempts failing I forgot to take build photos. I only took a few once I was finished, hopefully it will be enough. I hope you all can figure out how it all fits together from the diagrams and photos. I have tried my best to explain what I did.
Please let me know if there is anything confusing you.
Step 1: What You Need
Parts that you need:
1x 7805 Voltage regulator
2x 25v 10uf electrolytic capacitors
1x Micro USB cable
1x Deans Plug (Whatever Plug you use on your LiPo’s)
1x Small cable tie
Heat source to shrink the heat shrink (I used a hair dryer)
Hack saw to cut the board down to size
Step 2: Failed PCB's and Schematic
My original plan was to print my own PCB and use that but after two failed attempts I gave up and simply build a simpler version on Veriboard. Once I was thoroughly frustrated from my one hundredth attempt at printing my own PCB failing, I drew up a schematic of a very simply Voltage regulator circuit. The capacitors are not strictly needed as this is not rectified AC but it doesn't hurt to put them in.
Step 3: Building
I did not cut the board first which I think made it a lot harder later on. I would place the parts and determine the size of veriboard needed. Cut it first it will make life ten time easier later! I wanted to make this board as small as possible so I place the regulator on the top and the capacitors on the bottom of the board. I put the ground pins for both of the capacitors through the same hole to make it slightly smaller. On either side on the MicroUSB cable I drilled 2mm holes and treaded a small cable tie through. This will prevent the cable from ripping out at any point.
Step 4: Finishing Up
All that remains is to put heatshrink tubing over the entire board to prevent shorting during use. I used a hair dryer to shrink the tubing, I find it has sufficient heat to shrink all types of heatshrink.
See the image of the board powering a USB to SATA driver board.
The nice thing about this board is that you can simply replace the MicroUSB cable with a cable to charge your phone or iPod. Meaning you can venture out into the wild and still charge your devices using a large LiPo.
I hope you enjoyed reading this as much as I will enjoy using it!
If I can get my PCB etching working I will finish building my V2 board which has a voltmeter and an LED on it which will prevent over usage of the LiPo (If it works, a new instructable will be on its way soon).