This is yet another NE555 based DIY kit for electronics beginners. A long time ago, I had published this project on this page:

The electronic kit presented in this article is exactly the same circuit that I had published previously.

The circuit is an astable mode timer. The output frequency of the NE555 varies with the change in resistance of the photoresistor. When you block the light falling on the photoresistor, its resistance drops and that contributes to the change in frequency of NE555.

In this project, the output frequency of the NE555 has been set within the human audible frequency hearing range.

These are the components used in the circuit:

  1. 1 x PCB
  2. 1 x NE555
  3. 1 x 8 pins DIL Socket
  4. 1 x Photoresistor
  5. 1 x 1K Ohm resistor
  6. 2 x 330 Ohm resistor
  7. 1 x 5mm LED
  8. 1 x 10K variable resistor
  9. 2 x Screw terminal
  10. 1 x SPDT switch
  11. 2 x 0.1uF (Code:104) capacitor
  12. 1 x 8 Ohm speaker

Schematic of NE555 sound generator

The images of the kit can be seen below. You can see these images on Flickr also.