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  1. #1
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    Variable Current Load Relays

    I'm trying to come up with a wiring diagram to control a linear actuator (which will in turn push handbrake cables) using off the shelf relays and switches rather than a PCB.

    I think I've cracked it except for the adjustable bit that kills the power when it reaches a certain current draw.

    Is anyone aware of a relay (or something) that is adjustable and will switch off at a variable current?
    Regards

    Craig Perry

    No, I'm not "repairing" it, I'm fine tuning its performance.

  2. #2
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    Why not just use a micro switch at the limit of where you want the actuator to push?

  3. #3
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    That won't be self adjusting as the system wears, and I don't think the cheap actuators have limit switches built into them.

  4. #4
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    I assume you are trying to get away from spending £298 for a Handbrake Kit from Hollins? Good luck as many people will follow your route. We have now fitted three and all work 100% and was the best money well spent.
    Charlie
    Joint Area Rep - East Midlands Region
    AKCharlie - ''AKA SOOTY'' - AK GEN2 - LS3 - 6.2litre - 434bhp - A dream come true
    .

  5. #5
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    Thats correct, I've worked out a circuit that will make it go backwards and forewards on a switch, just need to workout the variable current load. Almost like a resettable, variable fuse.

    Actuators are £25 of EBay and the circuit so far will cost less than a tenner.
    Last edited by cperry; 19-05-17 at 05:57 PM.

  6. #6
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    Current sensing

    Quote Originally Posted by cperry View Post
    Thats correct, I've worked out a circuit that will make it go backwards and forewards on a switch, just need to workout the variable current load. Almost like a resettable, variable fuse.

    Actuators are £25 of EBay and the circuit so far will cost less than a tenner.
    = = = =
    Current sensing - wrap a coil around the wire supplying the current to the motor (actuator) run this through a simple variable (trim pot/variable resistor) comparitor circuit. set it to trip at desired current and switch off motor.
    Or, (creative solution) put a bulb in series, when the bulb goes dim, the motor is taking all the current. Use an LDR to measure the brightness of the bulb and switch off motor at set value?

    Do you have a link for the flea-bay (I mean Ebay) actuator?
    Alan.

  7. #7
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    I think I've found someone to have a go at the PCB's for me, one thing he's asked me is how many I want? Would anyone be interested in one if I can get it working? Of course it would be cheaper than the one you can buy from Hollins at around £110 each or there's no point doing it. As yet prices haven't been mentioned.

  8. #8
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    PCBs are very cheap these days. You would expect to pay less that $10 each for a little circuit like that.
    Cheers

    Myles D-W

  9. #9
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    Quote Originally Posted by cperry View Post
    I think I've found someone to have a go at the PCB's for me, one thing he's asked me is how many I want? Would anyone be interested in one if I can get it working? Of course it would be cheaper than the one you can buy from Hollins at around £110 each or there's no point doing it. As yet prices haven't been mentioned.
    I would certainly be interested

    Paul
    AK, on the road Oct 2012

  10. #10
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    Quote Originally Posted by mylesdw View Post
    PCBs are very cheap these days. You would expect to pay less that $10 each for a little circuit like that.
    That's exactly why I don't want to pay Hollins prices.

    If I can get 10 boards for $10 each I'd buy them all myself and still save money.

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