Connect with us

Creating A Half Wave Motor Controller

Discussion in 'Power Electronics' started by jamman1125, May 1, 2018.

Scroll to continue with content
  1. jamman1125

    jamman1125

    18
    0
    Dec 29, 2015
    Hi all,

    Im looking for some help in order to be able to understand and build a circuit based a schematic that I have found online. Im by no means an expert in electronics so hence my need for assistance in knowing what these components are and which ones to purchase.

    Screen Shot 2018-05-01 at 15.06.14.png

    The main requirements of the controller are that it will regulate the speed even under a load, as I am building a sanding drum. If i've left out any important info, let me know. Here is a link to the video the schematic was sourced from if its any help.



    Thanks in advanced!

    James
     
  2. Minder

    Minder

    3,066
    657
    Apr 24, 2015
    What is the reason for going 1/2 wave?
    Why not use a typical Triac style Universal motor power tool controller.
    The guy in the utube vid, mentions going full wave also.
    This method uses a triac followed by a full wave bridge if wishing to go DC.
    A Universal motor will run on either.
    M.
     
    Last edited: May 1, 2018
  3. Kabelsalat

    Kabelsalat

    154
    28
    Jul 5, 2011
    Hi.

    The least amount of information you need to understand the schematic is to know how a silicon controlled rectifier works. As with many other - just start reading about in at wikipedia:
    https://en.wikipedia.org/wiki/Silicon_controlled_rectifier

    Then - when you have read and get an idea on how it works you can ask more particular question.
     
  4. jamman1125

    jamman1125

    18
    0
    Dec 29, 2015
    Thanks for your responses. Well the guy did try and attempt to make a full wave version of the circuit, however it was very unreliable and did not consistently regulate the speed well. He did end up saying that for most uses the half wave design would be suitable, and in my case he is correct, as I dont need to operate the machine at high speeds.

    Your point on using a typical Triac controller is a good point, although I am not certain that these types of controllers would be able to regular speed even under load? As in my case I will be applying moderate loads when needing to sand larger items.

    I have just found this online which seems to be a very good price, do you think it would do what i require of it?
    https://www.amazon.co.uk/dp/B07C3SZ...locphy=1006602&hvtargid=pla-434396468379&th=1

    Also would it be better to run the motor on DC or AC for my purposes? And what would be the advantages/ disadvantages?

    Cheers

    James
     
  5. Minder

    Minder

    3,066
    657
    Apr 24, 2015
    The controllers you link to are PWM controllers and are not high enough operating voltage for your motor.
    The triac controller is used on most AC powered portable tools etc.
    There is very little difference running on DC or AC, some have found the motor to be a little quieter on DC.
    As my previous post, you can rectify the output of the Triac controller with a simple bridge if you wish to use DC.
    Universal motors are poor at RPM regulation without some kind of feedback sensor as they operate in a run away condition and RPM's are dependent on load.
    One demonstration of this is a vacuum cleaner, and covering the suction tube will cause the rpm's to rise drastically as it is now unloaded.
    M.
    .
     
  6. WHONOES

    WHONOES

    1,120
    311
    May 20, 2017
    If you were to go down the DC and PWM path, you could control the speed using a tacho connected to the shaft of your motor and use its output to vary the pulse width of the controller. A small DC motor could be used as the tacho.
     
  7. Minder

    Minder

    3,066
    657
    Apr 24, 2015
    If you don't yet have the motor, you could look out for a DC Treadmill motor and controller, some of the simpler controllers are SCR bridge controlled or the higher end is PWM.
    These should provide you decent torque without the large gearing needed with the Universal.
    M.
     
  8. jamman1125

    jamman1125

    18
    0
    Dec 29, 2015
    I already salvaged the motor from a thrown out washing machine. So im pretty much stuck with that.
    If i found a triac controller online that could handle mains voltage, would that then regulate speed with a good amount of torque?

    The dudes circuit in the video seemed the most simple and effective for being able to handle loads.

    Whonoes, the motor does have a built in tacho as it is a washing machine motor, however I could not find a circuit online which incorporated the tacho that I could build for a reasonable price (Under £15). Unless anyone can recommend a good circuit?

    Thanks
     
  9. Minder

    Minder

    3,066
    657
    Apr 24, 2015
    Motorola designed an IC for this which included a feed back sensor, it is a TDA1085 and uses a Triac to control the RPM.
    Specifically produced for washing machine control of a Universal motor.
    M.
     
    duke37 likes this.
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-