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Wide range constant current supply

Discussion in 'Electronic Basics' started by Greg, Dec 1, 2003.

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  1. Greg

    Greg Guest

    Does anyone have any ideas to build a simple constant current supply
    that can be adjustable from 10uA to 30mA? The input voltage can be
    from 24-40VDC. The typical LM317 does not regulate at low currents,
    and it seems that devices that can regulate at low currents, like the
    LM234, can not put out more than about 10mA.

  2. The Al Bundy

    The Al Bundy Guest

    What about a transconductance amplifier? These should be able to deliver
    such low currents.

  3. Many opamps can deliver current in this range, and an opamp with a
    small fet current booster (2N7000, BS170, etc.) works well in this
    range. What frequency response do you need?
  4. Greg

    Greg Guest

    Good idea. Frequency response will not be an issue, since the circuit
    will be operating in a DC mode.

  5. Greg

    Greg Guest

    Thanks for the replys. I got a circuit that works great. It took 1
    quad op amp, 6 resistors, one capacitor, and one pot.

  6. Baphomet

    Baphomet Guest

    How about posting the circuit?
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