Im working on a project that uses an electronic door lock. It needs a lot more power than an arduino can supply, so my thought was to use a transistor to switch on a second power source solely for the door lock. I've been trying to figure this out for hours. I thought transistors were just electrical switches. Just plug the + side of a battery into the collector of a transistor, and a side of the door lock into the emitter, then connect theother sides of both together.Then send a little electrical signal to the base from arduino. Nothings working. Please help.
A TIP31A is a NPN transistor so is most suitable for 'low side' switching of a device load, meaning you wire as follows. + external voltage to the load (solenoid), other load lead to the collector, emitter wired to external negative terminal, base wired to suitable series resistor (200-1,000 ohms), other side of resistor wired to arduino output pin, and finally a wire from arduino ground pin to external negative terminal (or emitter lead).
That make sense?