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Need a negative voltage from a 0-60V power supply

  1. Feb 13, 2009 #1
    I will have to power the following circuit:

    http://www.tekscan.com/images/flexi-circuit-new.jpg [Broken]

    I assume I can just hook the (-) terminal to the -9V input, the (+) terminal to the +9V input, set the power supply to 9V, and then toss a resistor between the -9V and the -5V?

    Would that work? And what value resistor would i need between the -9V and -5V?
     
    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. Feb 13, 2009 #2

    berkeman

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    Staff: Mentor

    First, on your figure, you should show the top opamp power supply pin as +9V and the bottom supply pin as -9V. The way you have them now is unconventional.

    Second, I think you mean to say that you will set your 0-60V single power supply to 18V, and you want to know the best way to make a middle rail be ground, as well as make a -5V supply. This is discussed a bit in your other thread, I believe. Turning a single supply into split supplies is not a great option, but can be done if the impedances and powers involved lend themselves to a resistor divider with adequate capacitor decoupling.
     
  4. Feb 13, 2009 #3
    Since your only powering an op amp, just use an inverting voltage regulator. I actually just finished hooking one up to an instrumentation amp a couple hours ago.
     
  5. Feb 14, 2009 #4
    altbraves, a two opamp, single supply design would get around this bias issue.
     
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