Slowing down Responder rotators


Junior Member
I managed to dig up a new Responder DX this week
Still in the box with red lense and a spare blue one :cool:
The only down side is it has the fast rotators.....(barf)

Does anyone know if the high speed was obtained with gearing or motor speed?
Does anyone know how to reduce the speed to 'normal'?

I have an old standard speed DX that doesn't not have these resistors, but it also has different motors and gears, so I'm not sure what's up exactly.


Last edited:


You will probably have better answers from others that have more knowledge of electronics than I, like @MtnMan .

I think the ”resistors” are capacitors for noice suppression.

Depending of the rotators rpm you probably need to reduce the motors rpm to half its rpm.
That means you need a resistor that take down the Voltage from 12V to 6V.



Premium Member
I do not recall any catalog offering different speed rotators. I know different vintage rotator assembly designs had faster rotators, but not as an option.


Gold Supporter
Count the teeth on the drive gear of the new one and the old one. Then see if the worm gears are the same diameter. If old v new are the same size/tooth count/diameter etc., then the motor is the reason. Could be that motors were swapped out on one of the bars?


Senior Member
@cmb56 is correct. Those are capacitors for electrical noise suppression.

Mechanical speed reduction, i.e. a gear swap, would be the elegant solution. You could experiment with adding resistors in series with the motor. That will reduce the speed, but also the torque, so the motor might be more sluggish.


Junior Member
Found a solution in case anyone else is interested....

I spoke to the avionics guy who built my new panel, and he suggested a 'Pulse Wave Modulator' or PWM. They are widely available and can be had for like 5 bucks, just snip the motor leads and wire into the PWM. Then set whatever speed you want with no load issues or heat.

Once I get around to ordering and wire one up I'll update with results.



Site Guru
Interesting. It does not drop voltage it shuts the power on and off multiple times a minutes to decrease speed. Very effective for motors as the inertia maintains consistency and is not jerky. Seems ideal. Very cool discovery.


Silver Supporter
Wouldn't the fs magnabeam and 2 speed firebeams be a starting point for how they slow them down?


Site Guru
Was thinking, some lights are wired inline. My have to split the bulb from the motor wiring or the bulb will flash.

Jennifer Rose Towing

Established Member
A PWM works great to control the rotators, was just going to recommend it. I used one in an MX7000 and made a pair of rotators dual speed.

When playing around with mine (looks like the one you pictured) I noticed it controls via the ground. I had to isolate the motor from common ground. I did not need to cut or change the positive wiring. It looks like this should not be an issue with your setup. Just don't run the lightbulb through the PWM too as that one is only rated at 2 amps.


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