Latching Circuit

Discussion in 'The Projects Forum' started by wolfhunter9154, Mar 31, 2013.

  1. wolfhunter9154

    Thread Starter New Member

    Mar 31, 2013
    2
    0
    Hello everybody, I've been working on a project for a few days and I'm having a little trouble with it. What I want to do is have the alarm from watch trigger a light that stays on until power is removed from the circuit. I have tried this with NOR gates with the outputs "crossed". However, for some reason, it will not hold the state it should be in and it will flicker on and off. This needs to be done with solid state devices, and I currently only have npn transistors, so the PNP and NPN latch isnt really an option right now. Any help is greatly appreciated.
     
  2. crutschow

    Expert

    Mar 14, 2008
    13,000
    3,229
    A single SCR would be a simple solution to latch the light on until the power is removed.
     
  3. wolfhunter9154

    Thread Starter New Member

    Mar 31, 2013
    2
    0
    Thanks, I ended up using a buffer with the output looped to the input. It didn't work the first time before I posted, but I tried again with a resistor from the input to ground and it stopped the flickering.
     
Loading...