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Mosfet Buffer Amp Circuit Help

Discussion in 'General Electronics Discussion' started by joolesison, Jul 1, 2017.

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  1. joolesison


    Jul 1, 2017
    hi folks, i'm obviously being lazy here but figure i'd risk members wrath (and save killing product) rather than read through posts for a week, apologies in advance.
    could someone with knowledge please tell me the simplest way (circuit) to take the signal from a signal generator and feed it into a transformer.
    i want to experiment with ferrites/windings etc etc and so need to amplify/buffer the signal from the generator to the experimental transformers, which will be all sorts of inductances and all sorts of reactances.
    the frequency will be below 60 khz.
    equipment i have is: a 0-30 bench top psu, a gwinstek gfg-8215a signal generator, a scope and multimeters etc
    i have some irf540n mosfets, so would like to use those if posssible.
    i was initially at least going to keep the signals to single sided square wave.
    i’ve never used mosfets and have heard they need different setup/biasing than bipolars and am scared i’ll kill the few semi’s i have before i get it right.
    thanking you in advance for your help.
  2. Audioguru


    Sep 24, 2016
    An amplifier has a certain maximum output voltage and maximum output current. You failed to say what they must be.
  3. joolesison


    Jul 1, 2017
    apologies, current max 2 amps and voltage 24 volts
  4. duke37


    Jan 9, 2011
    Use a resistor.
  5. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    Jan 21, 2010
    What is the output voltage swing from your signal generator?

    Do you want a bipolar output? (I.e. one that can both sink and source current?)

    The best option may be an option amp driven a pair of complementary MOSFETs.

    You will want to set up the circuit with the lowest gain that will give you the desired output. E.g. if the output of the signal generator is 1VRMS, then a gain of about 11 is all you need.

    The gates of the MOSFETs should be tied together with a small series resistor between them and the output of the op amp (say 10 to 100 ohms).

    If your per supply is +/-15V that's all you'll need, otherwise things get more complex. The best option on that case might be an h bridge, although that will limit you to square a wave output
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