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Thread: any EE's with some advice?

  1. #1
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    any EE's with some advice?

    Here is what I want to happen:

    Push NO momentary contact switch. Solenoid is energized. Momentary switch opens but the solenoid stays energized. Mechanical stop triggers a break (NC roller switch?) in the circuit, and the solenoid is powered off.

    What do I need to make this work? And how does the circuit look?

    Please keep it simple. My brain is too old for HARD work.

  2. #2
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    Carol, I'm sure a real EE can come up with something more elegant, but here's a very rough sketch of something that should work. The key is a normally open DPST relay. The NO momentary switch sends power to the relay, then one side of the relay keeps the relay energized until the NC switch breaks the circuit. The other side of the relay is handling power to the solenoid:


    I've got to go put a new headlight bulb in LOML's car right now, but if I get a bit a time later I'll try to do a cleaner drawing for posterity and replace this one.
    Attached Thumbnails Attached Thumbnails Carol's Relay Circuit 800.jpg  
    When the going gets weird, the weird turn pro. - Hunter S. Thompson
    When the weird get going, they start their own forum. - Vaughn McMillan

    workingwoods.com

  3. #3
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    Thanks, Vaughn.

    I went to sleep thinking about this one. I had the concept pretty much figured out as I went to sleep. I knew a relay was the answer. I am glad to see the schematic.

    Now to find the right relay. Anyone with ideas for resources. preferably surplus (read cheap!)?

    I understand the DPST part. What other requirements do I need to know and what is the proper terminology?

    Its kinda hard to find something when no one knows MY definition of doohinky!

  4. #4
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    What you described is a Latch switch, of the various types you would have:

    a) a Momentary, where the circuit is only open or closed while the button is pushed.

    b) a Flip-Flop, where the circuit can be either open or closed, but state is changed by the same switch.

    c) a Latch where the circuit is either open or closed, but stays that way when triggered by the main switch, another switch or power loss to the circuit allows it to change state.


    What type of voltages and type (AC or DC) are you controlling? Would help with determining the right relay specs to recommend.
    Darren

    To a small child, the perfect granddad is unafraid of big dogs and fierce storms but absolutely terrified of the word boo. Robert Brault

  5. #5
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    Thanks, Darren. I do find that 'latch' term when looking at relays.

    This circuit is intended to provide power to an air solenoid that controls an air cylinder. I can get the air solenoid in either 12VDC or 115VAC. I haven't ordered it yet. I want to have the entire circuit designed first.

    Amperage of the relay is also an issue. I say that because I see that information provided when searching for relays. So what do I need to know there?

    I want to push the momentary contact switch and release it without breaking the circuit. The NC switch breaks the circuit, dropping the power to the solenoid which then retracts the cylinder. That switch will be movable along the path of the radial saw motor, and then locked in place, allowing me to set repeatable stops for stopped dados.

    Will this work?

    https://www.surpluscenter.com/item.a...1&item=11-1291

  6. #6
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    I really can't wait to see this system in action....

  7. #7
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    Me either, Brent. Me either.

    But it will be an adventure!

  8. #8
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    Quote Originally Posted by Brent Dowell View Post
    I really can't wait to see this system in action....
    I really can't wait until I am far enough along in school to understand all this.

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