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Timed solenoid

Discussion in 'General Electronics Discussion' started by sbw, Dec 18, 2013.

  1. sbw

    sbw

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    Dec 18, 2013
    Hi I'm very new to circuit building and am trying to create what should be pretty simple.

    I have a solenoid and a power supply. I want to have the solenoid trigger every second. I have a 555 chip but I'm not sure what kind of capacitors and resistors I need to make this work.
    Any help would be really appreciated.
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    Welcome to Electronics Point.

    Can you tell us what voltage and current the solenoid requires.

    When you say once per second, that's fine, but for how long?
     
  3. sbw

    sbw

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    Dec 18, 2013
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,192
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    Jan 21, 2010
    OK, from looking at the specs of these (the catalog page to be exact) it appears that they are rated at up to about 4W. That's not a lot, but it's too much for a 555 on its own.

    Here is a page describing the 555 circuit and it allows you to select values for a certain on and off time.

    22uF, 27k, and 18k give you the approximate timing I think you require (it works out as on for about 0.7s, and off for about 0.3 seconds.

    Then you need to make the output drive a heavier load.

    Here is a page describing how to drive motors. (The solenoid is a very similar load). In this case the 555 circuit is a little different, do as per the one above.
     
  5. sbw

    sbw

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    Dec 18, 2013
    Steve, thanks so much for your help. If Im reading that second link correctly I would need a BUZ11 Mosfet Transistor to handle the additional power???

    As far as a power supply is concerned I have a 12v DC power supply putting out up to 3.2A is that useable for this project ?
     
  6. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,192
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    Jan 21, 2010
    A BUZ11 mosfet would be fine. It's a much heavier duty device than you need. As long as it's reasonably cheap, that's fine.

    Be aware that the gate of a mosfet is easily damaged. I would recommend that you place a 1k resistor in parallel with a 18V zener between the gate and the source. This will make it far harder to damage it once it is in the circuit.

    edit: As long as the power supply produces clean DC it will be fine. 3.2A is more than you need so the power supply won't be stressed.
     
  7. sbw

    sbw

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    Dec 18, 2013
    does the wattage rating of the 18V zener diode matter?
     
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