Reversing direction

Discussion in 'General Electronics Chat' started by boatsman, May 19, 2015.

  1. boatsman

    Thread Starter Senior Member

    Jan 17, 2008
    I need a simple 12vdc circuit that can switch between two 12vdc relays. The idea being that the first pulse operates relay one and the next pulse switches on relay No 2 in its place. I want to use a time clock to control this operation whereby the first time the time clock switches on (for a minimum time of 15 minutes) the first relay would switch on and then automatically switch off after a predetermined time and the next time the time clock switched on the second relay would operate reversing the direction.
  2. ScottWang


    Aug 23, 2012
    When you completed the procedure as above then how is the state of relay for next step?

    Below is a start that it is using one CD4013 to drive two stages of bjts and 2 bjts to drive two relays.

    Time clock → CD4013 divided by 2, Q0 → Bjt transistor → Relay.
    ................. CD4013 divided by 2, Q1 → Bjt transistor → Relay.
  3. studiot

    AAC Fanatic!

    Nov 9, 2007
    Note there are two types of relay

    Self latching which stay on once switched on with a pulse and need to be switched off with a second pulse.

    And those which require the 12V supply in order to stay on or off and switch off or on as soon as the supply is removed.
  4. boatsman

    Thread Starter Senior Member

    Jan 17, 2008
    I need the second type. I need the relay to operate only when it receives a voltage - maximum time to be activated is 30 seconds and then it switches off. The next time it is activated it operates the second relay, also maximum time of 30 seconds. Is there a simple way of doing this without any elaborate components?
  5. pwdixon


    Oct 11, 2012
    You need a processor to manage the timing, that way you can change the times as it doesn't look like you know quite what you want to do yet.

    If it's simple you want get an Arduino and a relay shield and you'll be sorted.
  6. Kermit2

    AAC Fanatic!

    Feb 5, 2010
    timer relays are commercially available and operate the way you describe your needs. google them.
  7. boatsman

    Thread Starter Senior Member

    Jan 17, 2008
    pwdixon thank you for your reply. I know exactly what I want. I already have a variable timer circuit to operate a 220VAC motor. I just need a simple circuit (if that's possible) to switch the output to another similar relay which will reverse the direction of the motor.