power amplifier- pls help me

Discussion in 'The Projects Forum' started by nza0104, Dec 2, 2010.

  1. nza0104

    Thread Starter New Member

    Oct 17, 2010
    4
    1
    Hi!
    I'm currently trying to amplify the power so that the power from my digital to analog converter can turn/ drive my motor using LM675 as in the first page of this datasheet:
    http://www.national.com/ds/LM/LM675.pdf
    I just replaced the RL with my motor, but how can I:
    1. Set the gain of the power amplifier? Is it by changing the 20k resistor only?
    2. How can I know/ verify what is the power amplifier gain without having to measure the voltage & current?
    3. How to limit/reduce the amplified power so that it is not excessive or will not damage my motor?
    4. I'm trying to make the motor to turn in both cw and ccw directions, but after implementing this amplifier as in page 1 of the datasheet, it only turns cw. How can I make it turn in both direction? I have a dual power supply. Do I need to use the circuit as in page 8 "Servo Motor Control"? If yes, how can I set the amplifier gain? Is it by changing the 1M resistor only?
    Sorry if my questions sound stupid/ very basic.
    Thanks
     
  2. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
    718
    You should be using an H-Bridge IC, such as the L298, rather than a power Op Amp.

    Another option is the HIP4080
     
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