I am trying to connect a Raspberry Pi / Arduino to a coffee machine. The coffee machine has a simple function, with a single button (momentary switch, on a DC cicuit) to dispense a coffee. I'm trying to add a parallel control to this button, such that the coffee machine can be triggered electronically (app, website, IR remote etc).
I have seen many examples of doing such projects with transistors as switches. I bread-boarded an example myself, using an NPN transistor in the common emitter configuration, with the load connected between the power supply and the collector of the transistor. That prototype worked great.
Opening up the coffee machine, the switch I want to add the transistor to is connected between the load and ground, so as far as I understand, this would mean needing a common collector setup, which won't be possible as the voltage of the secondary circuit is higher than the signal to the base.
If any of the above assumption is wrong, corrections are welcome. Perhaps there is a way..
If I can't use a transistor here, what alternatives could be used to control the secondary circuit?
Software engineer here, learning small pieces of electronics on the fly for this project, so you may need to assume less basic understanding than usual.