# Motor Speed Control Help Needed



## Doc Doom (Aug 28, 2008)

Several fellow haunters suggested that I could slow down a ceiling fan motor to run an Axworthy Ghost by using a router speed control available at Harbor Freight. I stopped by to pick one up and found they are not truely variable speed, but instead simply reduce the top speed to three settings. Since you use it with the fan on the high spped, it really is no differet that just using the fan speeds.

I've finished attaching a large pulley (made from serving platters) directly tothe ceiling fan. Works great except it go way to fast. Anybody know how to slow it down without using a Harbor Freight routewr speed control?


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## Nickinbama (Mar 10, 2010)

Can't you just use a reostat,like one used to dim a light bulb?That should reduce the current flow and reduce the fan speed.
I haven't tried it,but one of my fans has a reostat built in to control fan speed instead of the pull cord.


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## Doc Doom (Aug 28, 2008)

Nickinbama said:


> Can't you just use a reostat,like one used to dim a light bulb?That should reduce the current flow and reduce the fan speed.
> I haven't tried it,but one of my fans has a reostat built in to control fan speed instead of the pull cord.


That's what I thought initially. Tried it but it didn't work.


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## Zurgh (Dec 21, 2009)

I can only guess you were using a dimmer switch for lighting & not a fan-speed controller for a fan. They can look the same but they are different.


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## Dead Things (Apr 4, 2009)

You may also want to look at the size of the pulley that you are using on the fan motor. For simplicity sake, if the motor turns at 60 rpm and you use a 24" wheel, the circumference of the wheel is roughly 70", so the ghost would travel 70" per second. A 12" wheel will have about half the circumference and will travel 36" per second. (these measures are probably incorrect lol) I was going to make my axworthy with a 24" rim but changed to a smaller rim and got a much better result. Here is my video.


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## niblique71 (Dec 2, 2009)

I have the same question about a speed controller for my Axworthy. My setup uses a "laundry dryer" motor with a very small pully. The ghosts fly at perfect speed when it's not windy or rainy. But, if I can slow them down by 30-50% they'll be a lot less vunerable to damage or failure in bad weather.

If you search "ac electric motor speed control" you will get some results that look encouraging. However I don't know for sure that any of these will work. Some A/C motors are brushless, and some work on some kind of "pulse", and some will only operate at the stated RPM. I would love to have an answer before I invest more money in my setup.

One option I was considering was changing out my motor to a sewing machine motor. It already has a foot pedal which could be very convenient if I can find pulley's that will fit/work. Another option I was considering was buying an AC or DC motor that is already made to use with a specific speed contoller. I'd prefer to just "Slow down" my dryer motor since it's a proven bullet proof setup already. I'm not sure if a sewing machine motor can withstand the 100+ hours a year that my setup runs.

Obviously I'm also very interested in the responses that this thread might generate. I'd love an answer too.


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## DarkLore (Jan 25, 2009)

I'd love to hear more input on the topic. I have been sitting on an AC motor for several years (not literally, or it would have hatched by now). I'd love to consider something like an axworthy...but I'm sure the motor is a bit stronger/faster than necessary.


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## Doc Doom (Aug 28, 2008)

Went to both Home Depot and Lowes today. Neither carry a variable fan speed control. They both carry several controls but all of them are three speeds just like the fan already is. Back to the drawing board. Don't wanna spend $50 for a speed control. Will probably switch to a wiper motort. I picked up a 12V, 3 amp power supply at a yard sale for $3.


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## The Watcher (Sep 13, 2008)

Just curious, when you wired the switch. Did you use the old switch wires? Or run it straight to the motor? From what I have found, some motors are build for variable speed and some are not. But I am wondering is, even with a dimmer switch would you still only be able to get just 3 speeds just like with the original fan switch. The reason I asked we had a fan in our house that seemed to be that way once. You would have to turn the dimmer a fair ways before the fan would increase. The if you moved it back a little or forward a little the speed didn't appear to change. I never tried bypassing the switch. We just changed the fan and I didn't save it back then. But I am wondering if their might be a board or something between the switch and the motor? If so, could it be bypassed? Might be worth checking out.


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## corey872 (Jan 10, 2010)

Motor speed control is a pretty complicated subject. Some motors respond well - and can be controlled easily (mainly DC motors and brushed AC or 'universal' motors such as drills, routers and other power tools) Some are very hard to control - synchronous motors which 'lock in' to the power line frequency. For those you'd really need a variable frequency drive.

The ceiling fan is somewhat in the middle. The rotor (spinning part of the motor) is 'locked' to the rotating magnetic field created in the motor - this is why a dimmer doesn't work - you aren't changing the speed of the rotating magnetic field, you're just making it weaker.

To change the rotor speed, you need to change the rotating magnetic field speed. That is done by the capacitor. If you look at this schematic:










You see a capacitance of 3uF gives high speed, 2uF is medium, 1uF is low. From the picture you gave, your fan was 4.5, 5, and 6uF, - different values, but same theory.

You could try replacing the capacitor with a cap smaller than 4.5uF which would give you a slower speed (depending on the cap value). If you don't have a cap laying around, you could rewire the supplied cap in series. A 5uF in series with 6uF would give ~2.7 uF which would be the next lowest speed - and probably about 60% the speed of low.


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## The Watcher (Sep 13, 2008)

Thanks Corey872, I have never had it explained to me. but that was a great explanation. Good information.


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## Doc Doom (Aug 28, 2008)

corey872 said:


> To change the rotor speed, you need to change the rotating magnetic field speed. That is done by the capacitor. If you look at this schematic:
> 
> 
> 
> ...


Thanks for the info Corey. 
I know how to wire things in series, but it's been way too long since I got a C in my electrical engineering class to understand the wiring schematic to understand which wires are which. Can you tell me how to do it in layman's terms, like "connect the blue wire to the green wire? 
Thanks


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## corey872 (Jan 10, 2010)

That is going to be a hard one with out actually seeing the thing first hand. Do you have any more pics of the setup? In the earlier pic you posted are there actually 4 wires coming from the speed switch...seemed like red, brown, gray and black, IIRC?


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## Doc Doom (Aug 28, 2008)

corey872 said:


> That is going to be a hard one with out actually seeing the thing first hand. Do you have any more pics of the setup? In the earlier pic you posted are there actually 4 wires coming from the speed switch...seemed like red, brown, gray and black, IIRC?


Here's another pic. Black (hot) is going into the three way switch. Purple, gray and brown are going out of the switch to the capacitor. Another gray wire goes from the capacitor to the directional switch. The red goes from the capacitor to the internal workings of the fan I've also included a pic of the attached pulley.


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## corey872 (Jan 10, 2010)

I took a look at those pics, too. I'm still not 100% clear on how that fan is set up and I hate to make a suggestion of 'All ya gotta do is..." then have you come back with "Well, after I got the fire put out..."

Here is a page of good reading on ceiling fan speed control - from a guy who either loves fans or has way too much time on his hand. See if that can help you diagnose the capacitor issue.

http://kenklaser.gaiastream.com/2007/12/28/ceiling-fan-capacitor-solutions/#discussion


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## Doc Doom (Aug 28, 2008)

No wories Corey, I really appreciate your efforts to try to help me out. I had already spent some time looking over that web site. Found it by surfing "ceiling fan capacitor". I agree with your observation. I ended up more confused than ever. 

I found a fan motor control online that is supposed to be truly variable and not stepped. Figured it was worth $12 to try it out. It was shipped today. I'll let you know how/if it works.


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## Doc Doom (Aug 28, 2008)

Doc Doom said:


> I found a fan motor control online that is supposed to be truly variable and not stepped. Figured it was worth $12 to try it out. It was shipped today. I'll let you know how/if it works.


It didn't.

Actually the controller did slow down the moter a very small amount when it was on the slowest of the three pull chain speed settings. Not at all what I was looking for but it was noticeable. It wasn't noticeable on the two fastewr settings.


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