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Transistor Basic Circuits » Electronics » Semiconductor Devices » Transistor » Go on... » Experiment 11 - Transistor Logic

Experiment 11 - The Transistor Logic

Consider an arbitrary logic unit on an Integrated Circuit (IC) with two inputs A and B and one output Q...

Circuit of a logic unit with two inputs. (Enlarge)

Circuit diagram for a logic unit with two inputs.

You control the inputs of the logic gate with the pushbutton switches S1 and S2...

  • With open switches, the resistors R1 and R2 ensure that 0V is applied to the inputs. The logic gate interprets this as A = 0 and B = 0.
  • If you press S1, at the input A +9V is applied and is interpreted as A = 1.
  • If you press S2, B = 1.

The result Q is indicated by the LED.

  • If the result is Q = 0, the output is 0V. The LED is dark.
  • If the result is Q = 1, the output is 9V. The LED lights up.

In the next experiment, you replace the IC by a transistor circuit.