OPA 134 Speaker Amp

Discussion in 'The Projects Forum' started by ayushextreme, Apr 21, 2014.

  1. ayushextreme

    Thread Starter New Member

    Apr 10, 2014
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    I bought two OPA134's for making a Headphone amp. But I have some 4ohm 5W speakers lying around. Is it possible to make a portable speaker system out of it? Does anyone have a circuit?
     
  2. AnalogKid

    Distinguished Member

    Aug 1, 2013
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    Search the innergoogle for "current boost schematic diagram". There's a ton of 'em out there.

    ak
     
  3. ayushextreme

    Thread Starter New Member

    Apr 10, 2014
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    You mean a transconductance amplifier? Normally we use a power amp for the output stage right? But I want to keep the good OPA132 sound. Power amps like LM386 can drive a speaker. But OPA is just an opamp

     
  4. ronv

    AAC Fanatic!

    Nov 12, 2008
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    You will need some type of power amp, but don't waste your nice op amp on a 386.:)
     
  5. AnalogKid

    Distinguished Member

    Aug 1, 2013
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    No, I'm talking about hanging a couple of transistors on the output of the 134 to boost the output current. A complimentary pair (1 NPN, 1 PNP) of transistors can be connected as emitter followers or common emitter amps.

    For illustrating the concepts *only*, here are a couple of examples.

    http://www.seekic.com/circuit_diagram/Basic_Circuit/POWER_BOOSTER_1.html

    http://www.electronicsinfoline.com/...mplifier_has_transient_railtorail_swing.shtml

    http://www.deeptronic.com/small-audio-power-amplifier-using-op-amp-and-two-transistors/

    Note that the very popular Crown DC series of sound reinforcement amplifiers are basically an opamp plus a dozen or more power transistors.

    ak
     
  6. ayushextreme

    Thread Starter New Member

    Apr 10, 2014
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    Which complementary pair would you use to make a class AB power amplifier for a 5W output?
     
  7. bertus

    Administrator

    Apr 5, 2008
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  8. ayushextreme

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    Apr 10, 2014
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