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Low Cost Variable Speed  Rate Topic 
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 Posted: Wed Nov 8th, 2017 11:30 pm
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Richard Daugird
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These were recommended to me by another member. Anyone tried them? Says they are good for up to 220 volts, and 25(!) amps. For less than two bucks, seems too good to be true. I ordered a handfull, but it may be until mid December till I get them. 
https://www.ebay.com/itm/2000W-AC-50-220V-25A-Adjustable-Motor-Speed-Controller-Voltage-Regulator-PWM-NEW/172251512611?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

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 Posted: Sat Nov 11th, 2017 01:21 pm
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John Graves
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Interesting. I too would like to know. But what the heck. Cheap as chips.

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 Posted: Sat Nov 11th, 2017 02:19 pm
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David Allen
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It's a triac / thyristor device. Similar to a Lutron control.  It will work on certain motors but not others. You'll have to make careful testing to determine suitability.

Some motors will buzz annoyingly, others will appear work (they will be variable) but the motor will be drawing excessive amps and will overheat. 

This changes the AC voltage waveform from a sine wave to a chopped waveform. The effective voltage is reduced, but the waveform (which is also very important to the motor) is not the same and as such the motor's characteristics will not be the same.

All I'm saying is be careful. :cool:


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 Posted: Sat Nov 11th, 2017 02:31 pm
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David Allen
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We've discussed this before; but there is a very inexpensive method to get fixed, reduced voltage to a fan, without resistors and without affecting the waveform. It is called a voltage buck transformer.

This is not a variable speed device; but it will allow the fan's 3 speeds to be distinct and different. In other words, it will reduce the speed on Low and Medium to a great degree, without affecting High much at all. The volt buck transformer testing starts at about 6:00 in the video.


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 Posted: Sat Nov 11th, 2017 06:42 pm
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William Dunlap
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I've used the PWM modules on at least 10 fans of various configurations with success. Some more than others, though.
I always test them with my Kilowatt meter and set them to start on their own should the power be interrupted.
This is basic safety.

They seem to work best with the universal ac/dc motors, such as the Northwinds. You get the greatest variations in speed and control with those.

They also seem to work well with PSC motors as I have had a couple of  Emmy APG's that ran real nice with them.

I have yet to use a module in anything other than one of my custom made creations.

As far as I'm concerned, if I have a fan that meant to be at least mostly original, I would like to retain the original speed control device.

I'm definitely one to err on the side of safety as I have had a couple experiences with these fans that served to remind me that we a dealing with some amount of danger. (think rotating buzz saw hooked up to enough amperage to kill you).

Hope this helps.
Bill




Last edited on Sat Nov 11th, 2017 06:43 pm by William Dunlap

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 Posted: Sat Nov 11th, 2017 07:48 pm
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Duane Burright
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I was thinking about an article I had read about this a while back - you are really good at putting subjects like this in laymans terms

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