Whats a good way to make a delay

Discussion in 'General Electronics Chat' started by Alvin, Jan 29, 2008.

  1. Alvin

    Thread Starter Member

    Jan 22, 2008
    Say you want to keep a signal active for 3 seconds, or a 3 second delay before something comes on. Heck, what about 3 minutes?

    What would be a good way to do this?
  2. jegonz


    Jan 25, 2008
    For this an easy way maybe to use capacitors. So with an RC circuit you can control when to activate a transitor acting as a switch, to let the signal go out. But then you will have to calculate the R and C for the times you want, and also the values (voltage and current) to saturate the transistor. Or in other case can use OpAmp instead of the transitor and do a voltage comparator, so when the voltage in the capacitor goes up to the votage in an voltage divider, in the other input, the the output will be activated. Again the times you will have to calculate the values of RC to set the charge and discharge time.
  3. tian

    New Member

    Sep 23, 2007
    I suggest you use 555 then RC delay because RC delay depend on environtment;
    then for longer delay use counter.
  4. h.d

    Active Member

    Oct 22, 2007
    simply you can do it by capacitor
    other way by 555
    you can do it by MCU if you use it easy in software
    thats depends on your application