Timing 555 timer

Discussion in 'General Electronics Chat' started by Jiten Thapa, Jun 6, 2015.

  1. Jiten Thapa

    Thread Starter New Member

    Jun 6, 2015
    I have used an infrared led and I want to control a light with it using 555 timer, I want to turn off the light again after sending ir rays. Is is possible with 555 timer?
  2. Dodgydave

    Distinguished Member

    Jun 22, 2012
    you will need to use an op amp to receive the signal, then feed it to the 555 to trigger it.
    Last edited: Jun 6, 2015
  3. Wendy


    Mar 24, 2008
    You want to turn a light on and off with a IR LED. Push a button once for on then push again for off. Correct?

    Will this be an AC lamp?
  4. ian field

    Distinguished Member

    Oct 27, 2012
    The 555 is an acceptable choice because it is better to transmit a train of pulses at a set frequency and receive at the other end with a filter that only accepts that frequency - but you will need an integrator circuit to turn the burst of pulses when you press the button into a single pulse for the switching function.

    The switching function is best carried out by a bistable flip-flop, not too hard to find schematics online.

    The easiest receiver can be salvaged from a scrap TV or set top box etc, the tricky bit is identifying the 3 pins - earth is easy to find, and if it has a tinplate metal screen that will also be earthed, Vcc is almost always fed by a 100R resistor and decoupled with a small electrolytic. The signal lead is often the thinnest track that disappears among the maze of other tracks.

    These IR sensors need 5V, that are sometimes open collector and sometimes have an internal pull up resistor, they usually include frequency filtering at 36, 38 or 40kHz, so tune your 555 for best squarewave from the sensor.