Privacy Policy
Transistor Logic » Electronics » Basic Circuits » Transistor Logic » Get Started... » Digital Signals

Digital Signals

Look at the circuit diagram shown. An arbitrary logical unit has two inputs A and B and an output Q...

Circuit for a logic element with two inputs. (Enlarge)

Circuit diagram for a logic element with two inputs.

You control the inputs 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 unit 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.



Later the circuit diagrams show only the logic units, without pushbutton switches and LEDs. This offers a better overview.

Related Topics

Related Experiments


Useful Information

Social Media