Experiment: Resonant Inductive Coupling
Because the automatic drip irrigation system on the balcony needed power - at least some of the time - I decided to do some quick and dirty experimentation with resonant inductive coupling.
The basic idea is to have two coils of similar dimension (the simple case).
Drive one coil with an AC signal - in my case this was done using a function generator and hold the second coil close to it.
For optimal power transfer, make sure the receiver coil is resonating at the frequency you’re using to drive the sender coil.
The most difficult part if you don’t have to have a LCR meter at hand, is finding out the inductance of your - probably - hand-made coils. Luckily there’s several methods to measure this if you happen to have some other tools at hand. I’ve used method two outlined in this handy howto.
To design the resonator circuit for the receiver, there’s also a nifty little calculator.
I somehow didn’t manager to get this setup to drive a LED on the receiver end, but that might be down to either too little drive strength or me screwing up the receiver circuit. Probably the latter.
However, I was able to get a nice strong coupling at least on signal level when measuring it with my scope.