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Generators & Electric Motors General Discussion

Robbins & Myers Electric Motor Wiring Help


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  #1  
Old 07-21-2018, 11:41:25 AM
axepilot axepilot is offline
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Default Robbins & Myers Electric Motor Wiring Help

Greetings all.

So I have this Allen Organ Co. Gyrophonic speaker cabinet which has speakers set on a large rotating platter which is belt driven by this 1/10th hp motor. It's a pretty cool thing and I play guitar through it, which is my main thing - not electric motors.

I desire to wire this up using something like a light dimmer to control on/off and vary the speed. There's a unique multi pin connector but only (I think) 4 wires coming off the motor assembly. What I need to know is how to identify the individual wires and how I would wire them for that variable speed and on/off.

Is there perhaps a process I could go into using a multimeter?

Any help would be, of course, greatly appreciated.

https://i.imgur.com/2NiBsBt.jpg

---------- Post added at 09:34:45 AM ---------- Previous post was at 09:32:04 AM ----------



---------- Post added at 09:41:25 AM ---------- Previous post was at 09:34:45 AM ----------

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  #2  
Old 07-21-2018, 03:45:56 PM
Steve Dawkins Steve Dawkins is offline
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Default Re: Robbins & Myers Electric Motor Wiring Help

According to the motor's data plate, it is a 115 volts, DC, shunt wound motor. You will probably need to do more than connect it to a standard speed controller. I wouldn't even try a light dimmer.

I am not that familiar with DC motor control, but did find this with a quick search. https://www.practicalmachinist.com/v...wiring-283132/ One of the posts states that a DC shunt wound motor will have 4 wires, 2 for the field windings and 2 for the armature. Apparently, the field windings should be powered with constant 115 VDC, and the voltage to the armature is varied to control the speed. Maybe you can contact Bodine or one of the other manufacturers listed in that thread for help.

Thanks for posting your thread. I wasn't aware that the Allen Organ company had a rotary speaker. I have a Leslie #147, and love that sound. Good luck with your project.
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Old 07-21-2018, 04:38:20 PM
Bob Willman Bob Willman is offline
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Default Re: Robbins & Myers Electric Motor Wiring Help

As I recall from electronics school almost 60 years ago, a DC motor will run at rated speed and power with both field and armature supplied with rated voltage. Either an increase of armature voltage or a decrease of field voltage will increase speed.
Of course the power rating is only true at rated voltages.

Bob
WB8NQW
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Old 07-21-2018, 04:47:29 PM
Vanman Vanman is offline
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Default Re: Robbins & Myers Electric Motor Wiring Help

I have read of these speakers, but never seen one. That's really cool.

In this case all that's needed are two rectifiers and a baby Variac.

One rectifier is across the line and supplies the field continuously.

The other rectifier is across the output of the Variac and supplies the armature. This will give full range control from zero to rated speed.

These motor controllers exist. I have one for a small Bodine motor. It also has fuses and a switch to turn the whole thing on and off.
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Old 07-21-2018, 07:23:41 PM
Newoldstock Newoldstock is offline
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Default Re: Robbins & Myers Electric Motor Wiring Help

I know what this is.
I seen one on a Hammond organ one time.

So what you do is figuere out what you want to do slower or faster.

Slower you put a large potentiameter in series with the armature A1 wire to slow it down.
To speed it up put pot in series with F1.

THis motor is so small no need to be complicated just make sure you never ever leave the shunt field open or the motor will over speed.

If you want to make things more complicated this drive from KB is cheap and very reliable ( might make some hum you could hear.... just a heads up )
This drive will slow you down and speed you up a bit ( more for slowing than speeding up )
https://www.ebay.ca/i/192583835598?chn=ps&dispItem=1
( in practice it can put out about 130vdc maximum
For those unfamiliar with what this speaker does.
Listen to this.
The sound is caused by a spinning speaker ( or was back in the day ).
https://www.youtube.com/watch?v=53N99Nim6WE
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Old 07-21-2018, 09:45:24 PM
Radiomike Radiomike is offline
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Default Re: Robbins & Myers Electric Motor Wiring Help

My friend and I modified a Leslie speaker from its single speed AC shaded pole motor to one with a 12Volt DC motor with a PWM controller; powered from a modified PC ATX power supply. We could control the speed from near zero up to quite fast. It sounded superb. The tweeter had a rotating horn, the bass a rotating baffle.

For your unit there is quite a lot of inertia so perhaps a resistor (light bulb?) in series with the armature will ease the staring current. Lots of DC motor speed controllers out there. We had motor noise from the PWM and had to adjust the PWM frequency to achieve minimum noise.

So be cautious about using PWM on and older motor. Simple resistor control is as it says simple. Reducing the armature current will reduce torque so you may reach a low speed that is unstable and the motor may stall.

I would also contact Bodine to see if they have a data sheet, they probably do a speed control box that will match your motor

Mike
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Old 07-22-2018, 04:57:40 PM
axepilot axepilot is offline
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Default Re: Robbins & Myers Electric Motor Wiring Help

Thanks everyone. Really appreciate you sharing your expertise. Hell, I thought it was an a/c motor!
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Old 07-22-2018, 05:22:26 PM
Steve Dawkins Steve Dawkins is offline
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Default Re: Robbins & Myers Electric Motor Wiring Help

You definitely don't want to apply AC to that motor. It will, as we say here on the Stak, let out the magic smoke.
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