How do you step up a power transistor that will be coming from a nor gate which is in line to a relay. I need to step up the voltage from 5 to 12 volts in order for the relay to trip. Nominal current of the relay is 30mA.

 

connect gate via 1k to transistor base of BC639, a 4.7K from base to GND, Emitter to GND, collector to one side of relay coil and apply 12V to the other end of coil. Next connect a 1N4007 Diode across the relay coil, cathode of D going to +12V side of coil

 

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This is not the forum to ask this kind of question, it should have gone into the electronic chat forum.