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Simple off/on circuit help

Discussion in 'General Electronics Discussion' started by Bertman7807, Mar 31, 2013.

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  1. Bertman7807


    Mar 31, 2013
    Hello to all. I have a project that requires a bit more knowledge than I have. I need a switching circuit that has a momentary contact input that will turn on a relay with the first press and turn it back off with the second and so on. I am solder and component savvy but really have no idea about the design of a circuit like this even though I'm sure it's very basic. I have a mechanical relay that is a straight pull solenoid that rocks a toggle back and forth between 2 micro switches one at a time for every pulse it gets. It is burned up and I would like to build a solid state replacement. I will use a relay at the output to switch between outputs. Thank you in advance for any help. I hope I have included enough details. It can be a 12volt circuit.
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    Jan 21, 2010
    Can you provide some more details:

    1) do you simply want a circuit to toggle the relay, or do you want to eliminate the relay?

    2) If you want to eliminate the relay, what is the load you're switching (voltage and current)?

    3) If you want to retain the relay to do the switching, what current does the relay require?

    The simplest solution is to have a push on/push off switch controlling the relay (or indeed the load) but You may not want that.

    There are many push on/push off circuits on the net (google for "Push on push off schematic").

    Take a look at this video.
  3. CocaCola


    Apr 7, 2012
    I have linked multiple times to an over the counter momentary to latching module on these forums...

    Without more details I don't know if it will work for you but,it might be a candidate...
  4. Bertman7807


    Mar 31, 2013
    Yes, Steve. I need a circuit to toggle a relay. The circuit closes momentarily to change states. The output relay can be just a small one with 5 or 6 amp contacts. I just need to have a circuit that will energize and hold a relay with a "button press" for lack of better terms and then release the relay on the second press. Thank you for your reply
  5. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    Jan 21, 2010
    The video I linked to has such a circuit.

    Remember that you will need a reverse biased diode across the relay.

    Take a look at the video and see if the circuit he develops is OK (one issue is that holding the button down will cause the relay to turn on and off at a slow rate)

    I'm pretty sure there's enough information there, but ask if there's not.

    And the module that Coca Cola pointed out is another option.
  6. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

    Nov 28, 2011
    You can connect a two-coil latching relay so that it toggles each time a contact (e.g. a pushbutton) closes. I showed a design for this in The relay contacts are wired as a reversing switch; you can modify that arrangement, and/or use the latching relay to control a bigger relay.

    Latching relays aren't cheap, but the circuit is nice and simple.

    Edit: Also see post #13 on that thread. The relay I specified needs a slightly different connection from the diagram in the first post.
    Last edited: Apr 1, 2013
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