OpAmp or Transistor as a signal amplifier?

Discussion in 'The Projects Forum' started by Spiider, Mar 23, 2010.

  1. Spiider

    Thread Starter New Member

    Feb 22, 2010
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    0
    Hello! Thanks for all the wonderful resources here. First time poster looking for advice with my project.

    I'm basically designing a simple output amplifier for a PIC microcontroller project. I want to provide an square wave output of 0-12v, with a frequency up to about 2khz @ 50% duty cycle. I know all about programming PIC's and PWM etc. and can get all that working great, generating the input signal for the amp is not a problem.

    My question is what is the "best" method of amplifying the PIC PWM output from the normal 0-5v pwm output up to a 0-12v output. High current is not an issue this project is for signaling not motor control.

    I know how to switch ground side of a load using a Mosfet etc.

    I guess what I'm wondering is if there is a better way to generate higher voltage/low current signals using an opamp? Any component suggestions? My project is single supply 5v, if I go to an opamp design I guess I would need to provide a minimum +12v source for the amp using a 7812 or similar.
     
  2. Bychon

    Member

    Mar 12, 2010
    469
    41
    Modern rail to rail op-amps provide an easy way to get a 12 volt supply to provide a 12 volt square wave. Besides, op-amps have excellent input impedance, incredible gain, bandwidth out the kazoo, and are just basically easy to work with. With transistors, you are always figuring the input impedance, saturation voltage, load resistor, and how much more supply voltage you need to get to 12 volts of output.

    I say do it the lazy way because the lazy way works better. Now, get thee to mouser.com and start searching for rail to rail opamps that can survive a 12 volt supply.
     
    Spiider likes this.
  3. Spiider

    Thread Starter New Member

    Feb 22, 2010
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    Thanks! Sometimes we just need to hear it from someone else...
     
  4. Ghar

    Active Member

    Mar 8, 2010
    655
    72
    If you just want a square wave you can try a generic comparator which go from almost 0 to full supply (with a pull up resistor).
     
  5. Bychon

    Member

    Mar 12, 2010
    469
    41
    True. I didn't think of that.
     
  6. atferrari

    AAC Fanatic!

    Jan 6, 2004
    2,645
    759
    When you start browsing to choose an opamp, somebody else could have breadborded a simple transistor in switching mode fed with 12 V to get what you need.

    Sure, there are options.
     
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