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not stamp related but i need some help — Parallax Forums

not stamp related but i need some help

PFloyd36069PFloyd36069 Posts: 135
edited 2008-01-26 00:30 in General Discussion
hi

i am trying to figure out something other than a relay to switch power by using power.

thanks
bryan
·

Comments

  • Mike GreenMike Green Posts: 23,101
    edited 2008-01-25 01:33
    How much power? AC or DC? What voltage? What current?
  • PFloyd36069PFloyd36069 Posts: 135
    edited 2008-01-25 01:37
    Hi Mike

    The power i need to switch is very low. It is just connecting two pins on a 5 1/4 floppy drive.·I would imagine that it is dc. It shouldnt be above 5 volts.

    Thanks,
    Bryan


    ·
  • Mike GreenMike Green Posts: 23,101
    edited 2008-01-25 02:50
    A simple optoisolator may do the trick. It really depends on what's connected to the other end of the two pins. If one pin is connected to ground or +5V, a simple transistor will do. The StampWorks manual has some examples. You can download it from the Parallax website under Downloads.
  • PFloyd36069PFloyd36069 Posts: 135
    edited 2008-01-25 20:52
    What i need it to do is short the 5v pin to ground. Is there any specific models of the components that you specified? What do i connect to what? i have never done much with transistors, and have done nothing with optoisilaters so the extra help would be appreciated.
  • FranklinFranklin Posts: 4,747
    edited 2008-01-25 20:59
    See Mike's post above.

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    - Stephen
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2008-01-25 21:01
    This thread is being moved from the BASIC Stamp Forum to the Sandbox Forum.

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    Chris Savage
    Parallax Tech Support
  • PFloyd36069PFloyd36069 Posts: 135
    edited 2008-01-25 21:02
    how would i hook them up though. i am hooking the other end to the parallel port on the computer.
  • Mike GreenMike Green Posts: 23,101
    edited 2008-01-25 21:03
    Like I said, what you need to use depends on what's connected to the other end of the two pins. If one pin is grounded and the other pin is some logic input, then you don't need anything. You'd directly connect the Stamp I/O pin to the non-grounded pin and the Stamp would provide either +5 or ground (HIGH or LOW). I suspect that the non-grounded pin is connected to a resistor (called a pullup resistor) that is in turn connected to +5 (and some logic input inside the drive). You need to verify this first. The resistor provides a default +5V signal to the logic input (if nothing is connected). When you connect that pin to ground, it "pulls down" the voltage on the logic input. The resistor prevents a short circuit. It's probably some value from 4.7K to 10K.
  • PFloyd36069PFloyd36069 Posts: 135
    edited 2008-01-25 21:06
    how would i hook either one of those up though.
  • Mike GreenMike Green Posts: 23,101
    edited 2008-01-25 21:21
    First you need to figure out what you have. If you have a logic input and pullup as I described, then you don't need any additional components. If you want to use an optoisolator, the simplest is the 4N36 (search for a datasheet on the web). You wire up the LED portion like any LED (see What's a Microcontroller? - Exercise #1). The phototransistor part: base - not connected, emitter - to grounded pin, collector - to the other pin.
  • FranklinFranklin Posts: 4,747
    edited 2008-01-26 00:30
    First it's short two pins on a floppy drive then short 5v to ground then connect to parallel port. Why don't you draw up what you really want to do and include that in a post. The original question has been answered now the question has changed. Get your part together and we can help.

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    - Stephen
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