Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Photovoltaic cell as an on/off switch - circuit help

  1. Aug 14, 2008 #1
    Photovoltaic cell as an "on/off" switch - circuit help

    Hi all,

    My first post here. I'm a Mechanical Engineer prodding my finger where it shouldn't be - circuits!! I need help and Im hoping you folks can. PLEASE excuse the umb terminology - I dont know this world well!

    I want to turn a handheld camera on/off with a photovoltaic cell and am trying to build a circuit to do so. My problem is this. The on/off switch that I have sends one pulse when you press it on and one when you press it off i.e there is not constantly a signal coming from that switch. However, with the photovoltaic cell, when the light is there, I obviously always have an signal coming and when the light is off, there is nothing.

    I need help with what I need to wire inbetween to convert that constant signal so it is recognised as an "on" and that when that constant signal stops, it is registered as turning off.

    I'm imagining this is pretty simple?

    Many thanks!

  2. jcsd
  3. Aug 14, 2008 #2


    User Avatar
    Science Advisor
    Gold Member

    Re: Photovoltaic cell as an "on/off" switch - circuit help

    You could use a comparator circuit on the photocell output (using op-amps) to trigger a one-shot (using flip-flops) to give the pulses.
  4. Aug 16, 2008 #3
    Re: Photovoltaic cell as an "on/off" switch - circuit help

    great! Thanks for the comments. No idea what that stuff is but I'm off to google it all.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook