Relay switch time measurement circuit

Discussion in 'The Projects Forum' started by tufty88, Jul 19, 2010.

  1. tufty88

    Thread Starter New Member

    Jul 16, 2010
    Hello to everyone! I'm new here, from Scotland but working in the Netherlands at the moment.

    I'm currently developing a hardware module that uses relays in a driver circuit. The module interfaces external sensor circuitry with a lab PC, and enables the external circuitry to be programmed using software. One variable in the software is 'relay switch time'. Currently, the user enters an estimated safe switching time (based on the relay datasheet).

    I was wondering if their is any sort of hardware that allows for the measurement of this switch time, so that an accurate 'relay switch time' value could be given to the software automatically.

  2. JoeJester

    AAC Fanatic!

    Apr 26, 2005
    Use a dual trace oscilloscope. One input is on the switched side of the relay and the other input is on the load side of the relay contacts.

    Obtain the trace and measure the delay.

    on edit ...

    Trigger the oscilloscope with the switched side of the relay, negative slope.

    You should see zero volts for the switched side and a positive going voltage some time after the start of the trace. The time from the begining of the trace to that positive slope is your delay.
    Last edited: Jul 19, 2010
  3. windoze killa

    AAC Fanatic!

    Feb 23, 2006
    I think he was more asking for a permanent circuit that can provide some software with the switching delay.

    You could use a microcontroller (with some software and some associated hardware) to measure this delay and feed it to your pc. If you have the trigger of the relay detected by the micro and the actual switching of the relay detected by the micro then the delay time can be measured and pass to the PC.

    As far as the physical hardware I am sure someone will be able to point you in the right direction.
  4. tufty88

    Thread Starter New Member

    Jul 16, 2010
    Hey guys thanks for the replies,

    Thanks for the test set-up, I'll need to perfrom that type of test throughout my project. But yeah I was meaning a permenant feature to include in my circuit. Anyone got any ideas what type of hardware could make this measurment?
  5. beenthere

    Retired Moderator

    Apr 20, 2004