Help with alternating relays

Discussion in 'General Electronics Chat' started by firebat45, Aug 13, 2014.

  1. firebat45

    Thread Starter New Member

    Aug 13, 2014
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    What I'm trying to do is create a circuit with a single momentary button, when pressed will close relay 1, and when released relay 1 opens. When pressed again, this time relay 2 closes, and then opens on release. Then back to 1, etc.

    I've searched here and on google, everything I find is about latching the relays with a momentary switch, that's not what I'm looking for. It would be great if someone could give me a pointer here. Being able to alternate back and forth between the two would be great, and being able to expand to 3 or more relays would be even better, but it's not necessary for this project.

    Thanks!
     
  2. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    use a cd4017 decade counter set to 2, if you add more relays, set the counter to count upto the relay quantity.
     
  3. inwo

    Well-Known Member

    Nov 7, 2013
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    Last edited: Aug 13, 2014
  4. alfacliff

    Well-Known Member

    Dec 13, 2013
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    and for pump use, it insures that both pumps get equal time and wear out at the same time.
     
  5. inwo

    Well-Known Member

    Nov 7, 2013
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    There have been other threads about ratchet relays.

    They will do the same. Just run power from the button thru relay contacts to the load.
     
  6. crutschow

    Expert

    Mar 14, 2008
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    I believe an Alternating Relay is just an alternate action relay. He wants two or more relays to be sequential. For that the CD4017 counter is a good solution as DD suggested. Of course it will need a debounce circuit at the PB output and likely buffer output transistors to drive the relay coils.
     
    Last edited: Aug 13, 2014
  7. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    Here's how you could do it.
    U1 is a dual flip-flop. U1a provides a switch de-bounce function. U1b toggles between two states. Holding the button pressed will energise either relay (depending on which state U1b is in) until the button is released. Standby current is negligible.
    What load are you intending to control with the relays? Perhaps M1 and M2 could control it directly, thus avoiding the need for relays.
     
  8. firebat45

    Thread Starter New Member

    Aug 13, 2014
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    Thanks everyone for your help. crutschow was right, the alternating relay just switches from load A to load B with the button, I need something more along the lines of the dual flip-flop or decade counter design. I think I'll try the counter, being able to expand to more than 2 might be helpful in the future.
     
  9. crutschow

    Expert

    Mar 14, 2008
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    What type of relays do you want to drive?
     
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