Thread: Logic Gate circuit

Hi, I want to make a simple AND logic gate using transistors.

I found this diagram:



I believe it is using 2 NPN transistors to make an AND logic gate.

I've been trying to make a simple gate with two switches but I'm failing miserably.

The transistor I bought looks like this:




I just can't figure out where the ground end goes and how the switches are wired to the battery. Can someone please help me out? Can someone draw out a diagram including the power source for this AND gate with the two switches and a light bulb?

I've tried many times but can't figure out why the light bulb won't turn on when both switches are down.

thank you so much in advance.

sei italiano ? io nn sn ancora arrivato a quel punto con le porte ma penso che tu mi potresti aiutare nel mio progetto light saber, no ?

E, B, and C stand for emitter, base and collector. The emitter is shown on your diagram with an arrow symbol. The collector is the pin connected to the + voltage. The base has the input resistors connected to it.

You would connect one side of each of the the two input switches to A and B. The positive terminal of your 6 volt battery would connect to the other side of the switches and to the collector of the A transistor. The negative side of the battery would connect to where the ground symbol is shown on the 4.7K resistor and to one side of the 6 volt lamp. The other side of the 6 volt lamp connects to the terminal labeled "Out" on your diagram.

If you are still having a problem, take your voltmeter and measure the voltage to ground at each terminal of the transistors. Make a table. I'm sure somebody can help troubleshoot your circuit with that info.