time delay relays

Discussion in 'General Electronics Chat' started by Ericeugene, Nov 7, 2008.

  1. Ericeugene

    Thread Starter New Member

    Nov 7, 2008
    I read with great interest the subject matter on time delay relays (Chapter 5)--realizing that a relay is nothing more than a fancy switch. Each of the 4 types talked about in the lesson mentions characteristics of the relay when the coil is unpowered (de-energized). However, the relay I purchased a few years back from Diversified Electronics (TDE-24-AKA-010) requires a constant supply of voltage whether it is operational or not. It is my understanding that a "non-time delay" relay does not need this constant voltage. It only gets the necessary voltage when the relay is asked to make or break contacts. So, my question is "why is the constant voltage needed on my time-delay relay?" Obviously, this steady supply of voltage is not being supplied to the coil--or the device (alarm) I am controlling would always be sounding.
  2. KL7AJ

    Senior Member

    Nov 4, 2008
    Time delay relays can be anything from purely mechanical devices to sophisticated electronic timers/clocks. The conventional mechanical ones used a smalll hydraulic system....a small amount of fluid was forced throuh an orifice at a known rate, which activated a piston connected the the contact actuator. These could be surprisingly accurate....but most mechanical devices are espensive these days, while silicon is cheap. :)

  3. beenthere

    Retired Moderator

    Apr 20, 2004
    If a relay does not have power, it can't function. A TDR can't run the timer without power.