This is a SR-Latch build with Transistors. The button S1 or E1 (as an Input) on the left side is for the “Set” function and the button S2 or E2 on the right is for the function “Reset”. So when we are pressing the button S1 our output “Q” (blue LED P1) is setting to a HIGH/ON/1 position. But when we are pressing the button S2, you are resetting the output Q and it is going to a LOW/OFF/0 position, at the same time the output “inverted Q” (green LED P2) switches to a HIGH/ON/1 position. So the inverted Q is always doing the opposite of the Q. This circuit consists of 6 resistors, 4 NPN transistors, 2 LED’s and 2 DC voltage source’s. Please do NOT build this circuit 1:1 at home, normally it should have more resistors. This circuit is also NOT calculated, ALWAYS calculate your circuits before you’re putting them together in real life! This circuit just shows how two NOR gates work together resulting in a SR-Latch.
