Power amplifier - please help me

Discussion in 'The Projects Forum' started by nza0104, Oct 17, 2010.

  1. nza0104

    Thread Starter New Member

    Oct 17, 2010

    I would like to control 2 motors, one is 6V and 740mA and another one is 5V 200mA. But my I/O board (digital to analog) can only gives up to 10V and 5mA and the motor manufacturers do not provide any motor drivers. How can I drive this motors using through this I/O (digital to analog) board? Do I need a power amplifier? Can you recommend a specific power amplifier or any other alternatives? Soon I will also need to control the motors using PID and other control algorithms.

    I've tried to construct the power amplifier as in the Fig. 2 in the attachment: Vin is a 12V voltage supply and RL is a 1k ohm resistor, but it does not work. Instead of amplifying the power, the voltage and current across RL is almost zero. But the voltage across the capacitor is high? Or does it only work or AC?

    What should I do? Please help me. Thanks
    RRITESH KAKKAR likes this.
  2. SgtWookie


    Jul 17, 2007
    Look at an L2722 or L2724 power opamp; they can sink/source up to 1A current.

    See ST Microelectronics' datasheet; there is an example of bidirectional control of a motor using a single power opamp with logic-level inputs.

    You might get away with the industry-standard L272, but those are not a low-dropout type, and are limited to around 700mA sink/source.

    Don't use audio amps for power amps; you will probably encounter problems.
    Last edited: Oct 17, 2010