Discussion in 'The Projects Forum' started by Connect, Mar 2, 2010.

  1. Connect

    Thread Starter New Member

    Feb 24, 2010
    Any idea on how to make (or where to obtain schematic / kit) an IR sensor, which triggers a powerful bright light when it detects motion or body heat?

    Also, can anybody explain or clarify how relays actually work? As in, does the relay actually have to be connected in some way to the circuit it will be triggering, or is it remote? e.g an infra red alarm, relay triggers a siren of some kind... does the siren have to be physically connected to the ir circuit?

    thanks for your help
  2. SgtWookie


    Jul 17, 2007
    Google "PIR sensor kit" or "PIR sensor schematic" for lots of hits.

    A relay has to have connections to energize the coil (the coil changes the state of the contacts when energized/de-energized), and also connections to the switched side in order to work.

    There are some PIR sensor kits that have a wireless interface, but the switched relay still has to be wired into something to control it.
  3. hgmjr


    Jan 28, 2005
    One of the best ways to get your project up and running quickly is to go to your local radio shack store and purchase their PIR module (see this link ). I have purchased one of these modules and it works great as a motion detector. The only thing you would need to do is add the switching circuitry to interface to the light you want to illuminate.