I have gotten info on how to use a 5v Relay module with raspberry Pi from viewtopic.php?t=197339
It says that I should use transistor 2n2222 and a resistor r470 as follows.
Unfortunately I don't have 2n2222 but instead have only BC546B. I am using the setup with a Raspberry zero and from the relay unit I am using only one relay and leave the other 3 unused. The relay is used to open/close and electric strike lock (it uses 12V).
How could I use the BC546B with this setup? I also have a zener IN4007 and "4v7 611" and different resistors and leds