fan speed control

Discussion in 'The Projects Forum' started by monty3360, Feb 26, 2009.

  1. monty3360

    Thread Starter New Member

    Feb 26, 2009
    Hey all
    Need help with my project, have a 12v fan which i have to run of a plc analog output of 0/10v dc, plc can not run fan as current for fan is to high 40ma at full speed, does anyone know of a circuit i can use to step up voltage and also current.

  2. SgtWookie


    Jul 17, 2007
    One approach would be to use a power opamp, such as an L272, supplied with 12v, with a noninverting feedback to multiply the input voltage by 1.2. The output of the opamp won't reach the 12v rail, but it'll do much better than the PLC analog output will.

    See the attached.

    A better solution would be to have the PLC output control a PWM scheme, but that would be more complex, and I don't have time at the moment.