I have a MOSFET IRF Z44n and want to control 5V using 3.3V at the gate:
If I replace L1 with a voltmeter, the circuit behaves as expected: if SW1 is closed, I measure 5V. If SW1 is open, I measure 0V. I also can connect a lamp in place of L1, and it switches on when SW1 is closed (the lamp pulls less than 10mA).
Now the problem: if I close SW1 and connect the coil L1 that pulls normally about 500mA, I measure 0V in parallel to L1 with a total current of <10mA. Normally, the coil should pull its 500mA and generate a significant magnetic field (which it doesn't). As described above, connecting a lamp works.
Is the problem that the coil is pulling to much current? It isn't above the max current described in the data sheet. I really don't know what to do.