Timer to pulse a solenoid?

Discussion in 'The Projects Forum' started by jlydon29, Dec 7, 2013.

  1. jlydon29

    Thread Starter New Member

    Dec 7, 2013
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    Hello there, this is my first post on the forum. I've done as much reading as I can, but I can't seem to figure out my problem. I'm trying to activate a pull solenoid for 1 second, after a delayed timed reaction. I'm looking for the timer to be adjustable, in the range of 5 minutes (potentiometer?). While inactive, the solenoid would be in the push position, and after pressing a button, and then after the delay, I need to trigger the solenoid to retract for 1 second, then kill power. This needs to be a one time use, with no cycles. I was looking into 555 timers in the setup for the ham radio LED reminder, but I am coming to find out that it might not be able to handle the load carried to actuate the solenoid. Any suggestions? It needs to be as cheap as possible and battery operated, as I am not the wealthiest person around!

    Any suggestions that may help me research in the right direction, would be greatly appreciated! Thank you so much.
     
  2. wayneh

    Expert

    Sep 9, 2010
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    Adding a single transistor could fix that, if the rest of your circuit meets your needs. What is the current load of the solenoid and what is your power supply voltage?
     
  3. MaxHeadRoom

    Expert

    Jul 18, 2013
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    When you say 'kill power' do you mean kill supply power or just de-energize the solenoid?
    What is the function of the solenoid? Can you use a magnetic latch type?
    Max.
     
  4. jlydon29

    Thread Starter New Member

    Dec 7, 2013
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    I'm trying to activate a spring loaded push rod, something with ~10lbs of push. I was planning to use the solenoid to lock the inner sleeve into place via a hole lined up on the inner sleeve, while it's de-energized. Then, once you push a button, after the delay, the solenoid would pull out, allowing the inner sleeve to release. At which point, the solenoid's purpose would be finished, and doesn't need power until the sleeve was reset and the button was pushed again. As for the mechanism, imagine a compression spring toilet paper holder, with a plastic inner and outer sleeve.
     
  5. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    Looks like a double-timer job: one for the adjustable ~5min delay and one for 1sec.
    A 556 (dual 555) plus a power transistor (e.g. a MOSFET) should cope. We need to know the volts/amps the solenoid requires.
     
  6. salmanfazal29

    New Member

    Dec 7, 2013
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    use LM555 you can controle its frequency by variable resistor if your supply load is less then 18V....read data sheet available on google.com....
     
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  7. jlydon29

    Thread Starter New Member

    Dec 7, 2013
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    I'm looking to run the solenoid off of a 9v battery, so that sounds like it should work. I'd like to thank everyone for asking the right questions and giving suggestions that will help point me in the right direction! I'll post a photo of the project once it's all finished!
     
  8. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    If that's a PP3, then I doubt it will last long driving a solenoid with a 10lb pull :(. What current does the solenoid draw?
     
  9. MaxHeadRoom

    Expert

    Jul 18, 2013
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    The way I read it the solenoid was manually set and a release pin was operated to spring release it, if so the release pin would require much less effort?
    Max.
     
  10. jlydon29

    Thread Starter New Member

    Dec 7, 2013
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    Yes, that's exactly what it's for. The pin will lock the 10lb spring release in place. I'm not sure what the current will be. It will be a tinkering project, so I'm gonna buy a few different setups, until I find the most efficient items.
     
  11. inwo

    Well-Known Member

    Nov 7, 2013
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    Considering the low power available.
    The best way might be a single time delay, triggering a capacitor discharge circuit. Rather than a timed pulse.
     
  12. inwo

    Well-Known Member

    Nov 7, 2013
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    Woke up with a minimal component idea.

    Input pulse from S1 commutates scr.

    C1 charges thru R1 until D1 conducts. Fires scr, dumping C1 into R1.

    Small current thru R1 keeps scr latched until commutated again by S1.

    RY1 pulsed after RC delay.

    Couldn't find solenoid in library. RY1=Sol.
    Or it would work with relay also.:)
     
  13. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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  14. inwo

    Well-Known Member

    Nov 7, 2013
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    1 lb at 1/4 inch from a 9v battery. That's a tough job.

    Now I'm thinking in addition to capacitor discharge it needs a boost to higher voltage first. A strobe light circuit comes to mind.

    Will have to be very low duty cycle but not impossible.
     
  15. inwo

    Well-Known Member

    Nov 7, 2013
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