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Creating A Half Wave Motor Controller

jamman1125

Dec 29, 2015
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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
 

Minder

Apr 24, 2015
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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:

jamman1125

Dec 29, 2015
18
Joined
Dec 29, 2015
Messages
18
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.
Max.
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
 

Minder

Apr 24, 2015
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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.
.
 

WHONOES

May 20, 2017
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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.
 

Minder

Apr 24, 2015
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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.
 

jamman1125

Dec 29, 2015
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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
 

Minder

Apr 24, 2015
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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.
 
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