Hi. I've been able to find circuits to test creating a NOR gate - via an NPN 547 and a few diodes - connected to an LED. What I haven't been able to find is a good example of creating an AND gate with 2 diodes and a pull up resistor (along with an LED). When I try the circuit above (applying voltage to both "A" and "B"), when I measure between "out" and "ground", I can't get this circuit to make any difference when I turn off the voltage say at "A". I'm just seeing voltage drops across the diodes. Can someone tell me how I can do this as a test.