Three Steps to using the Vampire Charger to power your Phone:
Step 1: Attach the
device to a source of power
Step 2: Wait a second
Step 3:
Connect your USB device
Theory of operation:
Left part of the circuit: Tries to harvest ANY voltage at all from the terminals.
Use it to power the logic that decides which of the middle parts is run. If this one stays dead, the boost converter is on by default.
Otherwise the buck converter and transformer are on by
default.
Middle
parts: A transformer + rectifier (will take 110VAC and bring it to
12, or 220VAC and bring it to 24), OR a buck converter, OR a boost
converter.
Right
part: The output.
Bottom
part: The logic. We will be using window comparators, for efficiency.
Right now we are using an arduino to drive some relays to do a proof of
concept.
To increase efficiency, there’s going to be one LED for the whole board ( lit = OK, not lit = not OK) that will turn itself off when the USB cable is inserted, by seeing if anything is connected to the data line. (If it doesn’t turn off because the USB device is charge only, we’ll live with it, maybe add a toggle switch.)
I have been wanting to do this for almost ten years now. Three mins after seeing this hackaday project on HaD and I'm I just finished ordering the component list. It's literally in the mail lol. First project that made me "want" it for myself right away. This is great I'll post my final build as I plan to maybe add a magnetic easy connection component onto/with the alligator clips. ie: so that I can fast attach to any flat/flush contacts you can't get a good bite on with gator-clips.