What would be a feasible approach/circuit-design to make a self-powered wireless pushbutton, assuming it is even realistic?
This is what I mean by each of the three terms:
Self-powered: Power derived only from the mechanical action of pressing the pushbutton
Wireless: Pressing the pushbutton makes an RF transmission (let us consider a case with peak current draw of 40 mA during the transmission)
Pushbutton: Any type of pushbutton I can get at a hobbyist store or even build myself, but not a pushbutton where I have to turn a crank to activate the switch ;)
I would like to set up a little "network" project in my home (indoors), with these pushbuttons located at various points, but would like to do away with any battery power source, hence I'm experimenting with the self-powered idea. After all, the pressing of the pushbutton does bring in mechanical energy that could be used, and moreover, the resulting RF transmission event will be the only time the circuit will be alive or need to draw current (of around 40 mA).
My broken thoughts so far:
- I am considering using a capacitor/supercap that charges up during the mechanical event.
- Perhaps I could use some method of harvesting (piezoelectric, gear-based, etc.) of the mechanical energy from the push.
- I've noticed that there is this interesting chip that might be of use here: the LTC3588