If you don't know the voltage drop across a component - with component in the case being a single electronic piece or a "black box" device. All you have are the two wires. I get putting voltage onto the circuit then measure the voltage across the leads to get the voltage drop. But what if you don't know what the safe voltage threshold is on the device? Do you start out with using a 1.5v source, and slowly increase the voltage until you see a drop across the component?
I have a tipper rain gauge circuit that will close the circuit based on the magnet/hall effect transistor.
What I don't know, is whether it's a 3.3v - 5v or 9v circuit , so before I try to figure out it's current draw - I need to run current through it, and don't want to fry it trying to determine the voltage drop.
This is more of a general question, if I come across this for something else where I don't know anything about a device.
What is the procedure to determine voltage drop - and current used - both require power up the device/component?
I currently do not have a variable power supply (which is why I'm looking at stepping up in 1.5v increments aka "AA"'s) - but it seems I might need one in the future.