Solenoid Controller Substitution

Discussion in 'The Projects Forum' started by d.gelman, Aug 4, 2015.

  1. d.gelman

    Thread Starter New Member

    Apr 23, 2013
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    Hello,

    I have a pitch valve controller that can controls a series (upto 8) of 12V 130 Ohm solenoids. I want to replace these solenoids with more powerful 12V 16.4 Ohm solenoids. My idea is to include some sort of interface electronics between the existing controller and the new series of powerful solenoids. This interface would use the original solenoid signals from the controller to power a series of relays in order to power the heavier solenoids.

    I purchased a SainSmart 8 Ch relay board thinking I can connect the outputs of the controller to either the inputs of the board or solder directly to the relays of the board.

    http://www.sainsmart.com/8-channel-...arduino-pic-arm-dsp-avr-msp430-ttl-logic.html

    I did however pop the fuse on the controller since the relays had a 70 ohm impedance, too much current I suppose.

    Am I over thinking this? Is there a simpler solution? Perhaps a buffer?

    Thank you for your suggestions.
    Daniel
     
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,524
    2,369
    Are these AC or DC solenoids?
    The total for each rly and sol would be around 1amp.
    All powered would be close to 8 amps.
    What is the supply system designed/capability?
    Max.
     
  3. d.gelman

    Thread Starter New Member

    Apr 23, 2013
    7
    0
    Hey MaxHeadRoom,

    The industrial controller I am using and trying to retrofit beefier solenoids too has a 12VAC 1.5A power supply fused at 2.5 A (which I have already popped multiple times). The solenoids that came with the controller are DC and are powered at around 5V weirdly enough (when I probe the probe the powered solenoid with my scope). I think the unloaded voltage is around 7-8V but doing that causes the fuse to blow in the industrial controller.

    Thank you

    Daniel
     
  4. MaxHeadRoom

    Expert

    Jul 18, 2013
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    2,369
    One: You should be using BEMF diodes across the coil.
    Two: If the internal supply is not capable of the new load, You could look at using an external supply and have intermediate switching of the solenoids by a small SSR or mechanical relay?
    Max.
     
  5. d.gelman

    Thread Starter New Member

    Apr 23, 2013
    7
    0
    Max,

    Yes, I will use BEMF diodes across the coil.

    Yes, I want to use an external supply to power the beefier solenoids but use the control signals from the controller. Unfortunately, the mechanical relays I have have a 70 ohm impedance which draws too much current from the controller popping the fuse. Is it as easy to put a series resistor to match the impedance of the relay as if it were driving the smaller solenoids?

    Daniel
     
  6. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,524
    2,369
    The link says the relays take 160ma total (20ma x 8)?
    The solenoid supply will not affect it if they have a separate supply.
    Max.
     
    d.gelman likes this.
  7. d.gelman

    Thread Starter New Member

    Apr 23, 2013
    7
    0
    Hey Max,

    Thanks for your support. I was using the relays incorrectly and proper hooking up solved my issue.

    Thanks,
     
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