Trip alarm using IR led, photodiode and 555 timer

This project is a simple trip alarm using simple components:

  • 1pc – IR Led
  • 1pc – Photo Diode
  • 1pc – The legendary 555 timer
  • 1pc – 200nF capacitor (100nF also can)
  • 1pc – 550Ω
  • 2pc – 10kΩ
  • 1pc – Magnetic buzzer
  • 1pc – Tactile switch or any push button
  • 1pc – 9v battery or any suitable power source

A short video to demo the circuit:

Below is the circuit diagram …..

I change the 550ohm resistor to 330ohm, to make the IR light stronger.

To make this project usable/deployable in real life settings, we need to test and increase the sensing distant of the InfraRed Tx and Rx, split the Transmitter and Receiver into separate modules.

The output/alert method (in this circuit is the buzzer) need to be also more practical like, sent as SMS/Email to the control room, to a particular person or the buzzer/Indicator is situated in a room with personnel. Hmm….Will have to brainstorm a bit, will update this post again. 🙂