I have an IoT project in which I want to leverage existing bicycle LED lights, which have their own battery power. So, rather than using the current from the microprocessor to power the lights, I just need a way to wire my logic board to the bike light and control the on/off of the light.
I don't have an electronics background, so this might be a very elementary question. Is there an inexpensive electronics component that I can somehow wire or solder onto the bike light that can be controlled by another low-voltage circuit?
The ideal component would be able to switch rapidly on and off, preferably without sound / mechanical parts. I'm envisioning wanting to strobe the lights quite rapidly, again, controlled by the logic board.
If there are more than one kind of component, which might be the best for a small, DIY wearables project? IE: low-cost, easy to hook up, easy to source.
Best Answer
Relay:
simulate this circuit – Schematic created using CircuitLab
Advantages: simple, very well isolated, very little loss of power in load
Disadvantages: relatively slow (perhaps 10s of Hz), needs a fair amount of control current (typically more than logic circuits can supply)
Transistor (BJT shown):
simulate this circuit
Advantages: fast (easily up to Mhz), very small control current (typically < 1/50th of load current) required.
Disadvantages: No isolation, voltage loss across transistor switch, may be harder to wire up. Can't control AC circuits. Relatively low controlled output voltage - depends on transistor, can get >100, but typically less than 30V