Adjustable AC power supply

Thread Starter

Alchemy One

Joined Oct 5, 2019
217
Hello,
I like to run a DC Treadmill motor that runs on 100VDC and 23A

I figured I need to just make an adjustable AC regulator and then use a full bridge rectifier and possibly with a choke and or a capacitor too.
What I like to know are the specs of the components for the AC power supply. ( using 120VAC or 220VAC) whatever works.
Do I need to following?

1. A Triac BTA41-600b or?
2. A Diac BT3 or?
3. A linear potentiometer... 500K or?
3. A ceramic capacitor with a rating of 100nF or?
4. A resistor with the value 500Kohms or?
5. A heak sink

( To my understanding a higher rating capacitor has no determintal effect on a circuit while a lower one is not a good idea).
Thanks in advance for any help.
 

LowQCab

Joined Nov 6, 2012
2,628
It all depends on what You intend to do with the Motor,
how accurate / repeatable / linear does the control need to be ?,
how much Electrical, and/or, Mechanical-Noise can You tolerate ?,
do You need to be able to control the Motor Speed ?,
do You need to be able to reverse the Rotation ?,
do You need the maximum Power possible from the Motor ?,
do You need Transformer-Isolation for Safety ?,
how much Money do You have to spend ?

Personally, I don't like Triacs, they're incredibly Noisy, but they may be the cheapest way to go.
A PWM Controller is far more refined.
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Thread Starter

Alchemy One

Joined Oct 5, 2019
217
I was thinking to maybe install a metal cutting blade on it. I have three of these motors and one in particular look quite robust, it weighs a good 50lbs if not more. And of course it won't be like everyday all day long but once every so often for little project here and of course as a grinder, sharpner, sander and such. Just a hobby thing in my garage. They have no brushes, nothing noisy about them. The one with the sandpaper I have on it, can spin with serious rpm, probably in the mid to upper teenK rpm.
 

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MaxHeadRoom

Joined Jul 18, 2013
26,270
Most applications that don't resemble the requirements of a TM, the flywheel is removed on the motors.
If you do retain it, it is best to implement a ramp up start, as it does in TM applications.
No brushes?? The DC ones shown most definitely do.
 

Thread Starter

Alchemy One

Joined Oct 5, 2019
217
Most applications that don't resemble the requirements of a TM, the flywheel is removed on the motors.
If you do retain it, it is best to implement a ramp up start, as it does in TM applications.
No brushes?? The DC ones shown most definitely do.
==============================================
I don't know what TM means.
By the flywheel I assume you mean those round heavy ring things on each of the motor. I have tried to take them out is the only answer I have at the moment. I have failed. But that is not the point on my post.
If you mean that these Treadmill motors I have in the picture have brushes? They sure don't sound like brushed motors I am used to. To my knowldge brushes are used on what they call universal motors. These motors have permanent magnet. They require no brushes. And they are awfully quite and smooth. What kind of exotic brushes could that be. When I run my drill or my saw to cut wood, you can hear them things from a block away.
I believe these motro fall under the catagory of what they call asynchronous motor or some such thing.
And did you have an answer to my question in my post is what my real interest is?
Thank you.
 

MaxHeadRoom

Joined Jul 18, 2013
26,270
TM = TreadMill.
DC motors are the main motors used in TM applications. They are very quiet.
Universal motors are just a variation of a DC motor and have series wound fields.
The TM DC only version has PM (shunt) fields.
You can use a Triac followed by a DC bridge rectifier, but they are not the best mode of control, rather coarse.
As @LowQCab pointed out, PWM is the better choice.
The flywheels are often threaded on and the thread is right or left hand depending on the direction of the motor when used in a TM.
There are many designs out there, as well as cheap ebay versions. Which in some cases are for Universal motors so they just need the bridge rectifier.
 

Thread Starter

Alchemy One

Joined Oct 5, 2019
217
TM = TreadMill.
DC motors are the main motors used in TM applications. They are very quiet.
Universal motors are just a variation of a DC motor and have series wound fields.
The TM DC only version has PM (shunt) fields.
You can use a Triac followed by a DC bridge rectifier, but they are not the best mode of control, rather coarse.
As @LowQCab pointed out, PWM is the better choice.
The flywheels are often threaded on and the thread is right or left hand depending on the direction of the motor when used in a TM.
There are many designs out there, as well as cheap ebay versions. Which in some cases are for Universal motors so they just need the bridge rectifier.
============================

PWM need DC power supply to my knowldge?
Is that not the case?
Back to my question in the post...... again.
------------------
In regard to that flywheel thing, I have not been able to take them out for the life of me. I am aware of their tread being backwards.
That larger red motor have a nut on the shaft. I took that nut out, regular Thread. So I blissfully thought that the flywheel will jsut come right out. Nope. Threaded or not, it won't budge and if it is threaded, it should just turn like the nut did. Nonetheless I didn't want bust the shaft on the motor trying to man handle it.
The first one with the sandpaper I glued on it with double faced tape, same thing. I guesss you supposedly hold the flywheel by hand while you run the motor in reverse. Sure, it seems to work for folks on Youtube perfectly fine.
 

Ian0

Joined Aug 7, 2020
6,677
Triac followed by bridge rectifier is one choice. Bridge rectifier followed by thyristor was the way it was done for years before high-frequency PWM came along - in fact, SCR control IS PWM, just PWM at 100Hz. A higher frequency would be better, but it might whistle, and if you take the PWM frequency above audible range, core losses will start to increase.
 

LowQCab

Joined Nov 6, 2012
2,628
If You use a Ribbed-Belt, like the original installation, You don't need to remove the Flywheel,
in fact, it might even be an advantage.

So ......... Do You want refinement of Control, or down and dirty ?,
( along with the other questions listed ).
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MaxHeadRoom

Joined Jul 18, 2013
26,270
To remove or not, usually comes down to the application, those that adapt TM motors for controlled machining etc, generally need to remove the flywheel to obtain faster response .
If left in place, you have to ensure you do not power on with the pot at max.
 
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