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Urgent - LM1458

Discussion in 'Electronic Design' started by Alan Smithee, Nov 27, 2003.

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  1. Alan Smithee

    Alan Smithee Guest

  2. Ben Bradley

    Ben Bradley Guest

    In sci.electronics.design, "Alan Smithee"
    Most any op-amp, whether dual in one package, quad in one package,
    or two singles, will work in this circuit, as long as the max power
    supply voltage ratings is less than the +V and -V values. The 5532
    will work but it's overkill. but you should put a 5k or so resistor in
    series with the wiper of the 25k pot. The 5532 has internal diodes
    across the + and - inputs, and if the pot were turned up to the output
    side with more than half a volt acrosss the output cap, it would dump
    a lot of current into the diode and burn it out. Other op-amps might
    not like their inputs going above their positive supply, either:
    there's no voltage given for +V and -V, and if the out voltage is
    greater than +V and the pot is turned up, the - input could go above
    the +V op-amp supply.
    Hey, aren't you a famous film director?
     
  3. Alan Smithee

    Alan Smithee Guest

    Thanks very much - situation is now resolved
    Yes, but I'd rather not talk about it
     
  4. Ben is quite right that essentially any dual opamp will work.

    Myself, if I were building that circuit and had the luxury of choice, I'd
    look for an opamp with low DC offset and low bias current, to improve
    accuracy. But myself, I wouldn't build that circuit in the first place.
    Instead, I'd probably use a variable regulator chip, such as the LM317:
    better reliability, fewer parts. If I wanted the adjustable current
    limiting I'd keep the "bottom" part of the circuit, although I'd probably
    use a comparator instead of an opamp.

    But you say you're in a big hurry, so the answer is "use whatever you've
    got, it don't matter".
     
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