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-   -   Making 2rpm motor spin slower? (http://www.diychatroom.com/f18/making-2rpm-motor-spin-slower-13863/)

mikehende 11-28-2007 02:40 PM

Making 2rpm motor spin slower?
 
Hello all, I got a Disco ball preparing for the XMAS season but it is spinning a little too fast at 2rpm and gets you dizzy, I would like to have it spin slower at around 1rpm would be ideal, I tried a Lamp Dimmer switch and plugged the ball motor directly into it but this did not help, when I move the slider, at a certain point it would either turn the motor on or off so it does not control the speed, another electrician told me to try a Fan control switch but another told me if the Dimmer switch does not work then the Fan control which does the same exact thing will not work either.

Can anyone here offer a simple cheap solution please as this ball will only be used once or twice this season. I would like to get a device which would simply plug into the wall and then I can plug the motor into that device but if that's not possible then I am a little handy, I can cut the end of the motor wire and wire it directly unto the device which will control the speed og the motor, any ideas/advice/referrals please? Thanks.

rick32 11-28-2007 02:47 PM

How about a mineature gear reducer?

mikehende 11-28-2007 02:49 PM

I am not am not an electrician Rick so I have no idea of what you just referred to or where I can get one? I will do some reseacrh on it on the net but I would appreciate some link or something to it in the meantime please?

perpetual98 11-28-2007 03:50 PM

What is currently powering the motor? Straight into the wall, or a wall-wart?

scorrpio 11-28-2007 04:04 PM

The idea is to remove the disco ball from its shaft, mount it on a separate shaft, and then connect shafts with a rotation-reducing connection - either a couple gears or 2 wheels and a belt.

mikehende 11-28-2007 04:23 PM

The ball hangs on the motor and the motor has a standard 6' cord with a 2-prong plug which goes into the wall.

http://www.discoballstore.com/dibamo.html

perpetual98 11-28-2007 04:47 PM

I'm guessing that if it indeed does run on 110v and isn't just transformered down in the housing, that a potentiometer might work, but that's just a guess.

mikehende 11-28-2007 04:52 PM

@Scorpio

One major problem is that the ceiling is only 8' high so if I have to drop the ball down any further by using any extension between ball and motor then this will be too low which is why I am looking for something to control the speed from the wall's AC outlet.

junkcollector 11-28-2007 07:47 PM

What type of motor does it have?

mikehende 11-28-2007 07:57 PM

110 volt AC Motor

here's a pic

http://www.discoballstore.com/dibamo.html

junkcollector 11-28-2007 08:17 PM

I know that, but the type. Did you have it apart yet? If I knew the type and if there is any other circuitry inside the case, I might be able to figure it out

Possible types: DC brush with internal circuitry (unlikely)

AC shaded pole (my guess)
AC Capacitor start, or run. (very unlikely)

Edit; could also be some type of AC synchronous motor.

mikehende 11-28-2007 09:00 PM

I have no idea what's inside this motor, I will try to get the info tomorow from the manufacturer.

bjones 11-28-2007 11:07 PM

Pwm
 
The dimmer you had was probably a cheap dimmer that uses resistors (or something) to reduce the voltage to the motor. If it's a 100v motor, it needs close to that to operate. If you drop the voltage to 90v, it might spin slower but at a certain point there won't be enough voltage to make the motor spin. So 50v might seem like it will reduce the speed by 50% but in practice it won't spin at all.

A fan control switch probably uses PWM (pulse width modulation) and will be more expensive. PWM supplies the same voltage but it does it in pulses. So instead of always having electricity, it will switch the voltage on and off really fast. It does it very quickly so that the motor turns on and off many, many times a second. It gives you the full voltage so the motor will spin but the motor won't get to full speed because it doesn't have the voltage on long enough.

If you are really interested in how it works, read this: http://en.wikipedia.org/wiki/Pulse-width_modulation.

Long post short -- buy a more expensive dimmer and it will probably work.

frenchelectrican 11-29-2007 01:15 AM

the two most common motor for that size is either shade pole motor or schronous motor one of the two.

if so you can swap for diffrent gear motor to run even more slower.

some electric motor shop may have this kind of item other wise check out some wholesale centre like W.W.Grainer or others

Merci, Marc

elkangorito 11-29-2007 06:43 AM

I'll put my money on the motor being a shaded pole type, the speed of which can be controlled by a "leading edge" (not "trailing edge") electronic dimmer.

The speed of synchronous motors cannot easily be controlled & therefore, if the motor is synchronous, you will need to use gearing.


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