DPDT Relay/Pole Flip-Flop

Discussion in 'The Projects Forum' started by Rdyar1828, Nov 9, 2012.

  1. Rdyar1828

    Thread Starter New Member

    Nov 6, 2012
    5
    0
    First post here.

    I've got a small linear actuator that is controlled by a servo. The actuator's displacement is monitored through wipers connected to an Arduino. I want to have the actuator extend for x distance then retract to its original position.

    The circuit shown is basically how I wanted to do it at first, just to keep it simple. Through a NPN transistor the Arduino activates the coil. While in normally closed position the actuator moves forward, but when the coil activates it stops moving until it returns to normally closed position and after a few cycles the contacts on the relay go kaput. Any ideas or advice on what I can do to get this setup working, or a similar setup to replace it.

    Thanks!


    Ignore the values in the schem. it's only a visual representation
    [​IMG]
     
  2. panic mode

    Senior Member

    Oct 10, 2011
    1,320
    304
    circuit with relay contacts servo etc (part you think it is not working) is correct. if the contacts are welding or blowign up, it is because your relay is not rated correctly OR because you did not wire it according to circuit. I suspect that actual wiring is wrong and you get short circuit so relay contacts weld.
     
  3. Rdyar1828

    Thread Starter New Member

    Nov 6, 2012
    5
    0
    Well that's good to hear, I recheck everything and see if I have any luck.

    Thanks
     
  4. panic mode

    Senior Member

    Oct 10, 2011
    1,320
    304
    are you sure V1 and V4 are isolated from each other?
     
  5. Rdyar1828

    Thread Starter New Member

    Nov 6, 2012
    5
    0
    100% positive
     
  6. tubeguy

    Well-Known Member

    Nov 3, 2012
    1,157
    197
    Could you post specs on the servo ?
     
  7. Kermit2

    AAC Fanatic!

    Feb 5, 2010
    3,789
    945
    Try reversed diodes across the contacts. The inductance of the servo windings is rather high. This is the same type of protection afforded by a reverse diode across a relay coil.
     
  8. ScottWang

    Moderator

    Aug 23, 2012
    4,855
    767
    What kind of relay will working on 1V?

    The below is the general connection, transistor and arduino need a common ground.
    [​IMG]
     
  9. Rdyar1828

    Thread Starter New Member

    Nov 6, 2012
    5
    0
  10. tubeguy

    Well-Known Member

    Nov 3, 2012
    1,157
    197
    Are you using the actuator with the limit switch option or the pot option?

    Your circuit should work with the limit switch option, but if you are using the pot option then it appears power will be continuously applied to the servo in the N/C position. Not good for the servo according to the data sheet.
     
  11. Rdyar1828

    Thread Starter New Member

    Nov 6, 2012
    5
    0
    Hey guys, first off thanks for all the replies! Secondly I've got the circuit working properly, instead of flopping the outputs I'm flopping the input from the battery and that seems to be working correctly. I'm not sure why I didn't think to try that sooner, but I'm still slightly puzzled as to why the previous setup wasn't working right. I've included and updated diagram with proper voltages on the sources, so take a look if you want.

    Again,
    Thanks!

    [​IMG]
     
Loading...