Build a DPDT Switch

Discussion in 'The Projects Forum' started by nicmon, Mar 19, 2011.

  1. nicmon

    Thread Starter Member

    Mar 18, 2011
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    I can't find a Push Button which acts as a DPDT Switch, I want to use it to build an Eject button for a DVD-Drive. it works in the way that the Drive have a current of 3.3V in whole time and once we disconnect the wire from 3.3V and connect it to GND shortly and put it back to 3.3V, the Drive will be ejected.

    XBoxLW.jpg

    a quick solution would be use a slider for that.

    XBoxLW2.jpg

    my question is, is it possible to use a Push Button combined with a Transistor to invert the current and build such a circuit?
     
  2. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    If you can add resistance between 3.3V & drive without disturbing normal operation, then a SP ST NO push button connected between drive & ground should work. Resistance should be high enough to not effect 3.3V & low enough not to bother drive.
     
  3. Kermit2

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  4. nicmon

    Thread Starter Member

    Mar 18, 2011
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    wow that's very big, I have ordered one once before, they don't match into a normal circuit.

    sounds like a very good solution, do have an idea about the value of that resistance?
     
  5. jpanhalt

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    Jan 18, 2008
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  6. Bernard

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    Aug 7, 2008
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    sounds like a very good solution, do have an idea about the value of that resistance?[/QUOTE]
    Assuming that the 3.3V is a power supply, it should support a current of 50 mA, so I would try 68 Ω to 100Ω. Why the requirement for a double pole SW?
     
    Last edited: Mar 20, 2011
  7. nicmon

    Thread Starter Member

    Mar 18, 2011
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    Sorry, I meant actually a Single Pole (SPDT) Switch.

    I'm using a normal PC Power Supply and a LM1086 Voltage Regulator to reduce the 5V from Power Supply to 3.3V.

    I put 2 100K Resistors between the Drive Wire and Ground and it worked, but the problem ist that Voltage Regulator becomes very hot after pressing the Switch, so it seems that I still need some changes.

    hier is a simple version of my circuit, the RED Wire is which I'm trying to connect to Ground via Push button:

    XBoxLW3.jpg
     
  8. Kermit2

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    [​IMG]
     
  9. Bernard

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    'Not sure where you put resestor & PB SW. This is what I was thinking.
     
    nicmon likes this.
  10. nicmon

    Thread Starter Member

    Mar 18, 2011
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    Yes, that worked, really appreciate for your help.
     
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