I have a momentary push-button switch in an existing installation that I can hijack for a project. The project requires a 5 VDC relay to activate and the rest of the circuit is powered through there.
But how do I make a momentary push-button switch activate a relay?
I built a circuit like this in the Falstad circuit simulator.
The output is the collector of the NPN with the 1 kohm base. I connected this point to the negative terminal of the relay and the positive terminal is connected to Vcc (12 V). This doesn't work, because the relay coil pulls the collector up and breaks the circuit.
If I add another NPN with its base connected to the NPN with the 1 kohm base it pulls the PNP base down and the PNP will never activate.
Do note I'm a newbie, just a hobbyist here. Btw, I have no access to flipflops, diodes, etc. All I have are resistors and NPN/PNP and various capacitors and a few relays. I will have to drive 2 hours to buy other components if need be.