Variable Speed Drive Circuit

Discussion in 'Electronics Resources' started by Dave C, Apr 13, 2011.

  1. Dave C

    Thread Starter New Member

    Apr 30, 2008
    I am in the process of converting my pillar drill to run on a DC brushed motor that I removed from a treadmill. The motor is a 180Vdc, 4Amp 4000RPM motor. The treadmill was supplied with 240Vac single phase (UK supply).

    Can any anybody help with a control circuit diagram. I would like to have an option to connect a magnetic reed switch for the feed back loop.

    I have been looking on web for a circuit but have only found circuits for low voltage/power supplies and my electronic knowledge is not of a standard to modify the circuits with any confidence.

    I would appreciate any help.


  2. jpanhalt


    Jan 18, 2008
    KB drives makes very inexpensive AC to DC drives for the type of motor you describe. They have several safety features in addition. I have gotten new drives for less the $100 on ebay or from industrial suppliers.

    Considering your time and costs only, it is probably not worth trying to design and make one. Add to that the reliability and features of a commercial product, it does not make sense to DIY, unless you just want the experience.

    From an experience standpoint, this forum frowns on DC supplies that are not isolated from the mains with a transformer. If that policy is still followed, your design here will need to start with a transformer, which may cost about as much as the commercial controller.