Timer Frequency Control  


We will use the schematic diagram to assemble the siren circuit on the circuit trainer.

Materials / Main Page


Step 1:

  • Study the schematic diagram to determine how the parts are hooked together.
  • Refer to the materials pop up window to see the different components.

Electronics Experiments Procedure


Step 2:

  • Hook up the components on the circuit trainer.
  • Set the power supply to +9V DC.

Electronics Experiments Procedure


Step 3:

  • Power up the circuit and adjust R1 until the indicator LED on the trainer flashes at about 2 flashes per second.
  • Adjust R4 until a clear siren sound can be heard.
  • Connect the speaker output to an oscilloscope probe, and adjust the scope until the waveform is visible. Notice that the signal frequency varies at about ½ second rate.
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