Date: Fri, 08 Mar 2002 11:21:44 -0500 (EST)

Author: Steve Wonnell

Subject: Re: selsen motors


Jerry, if that description immediately below of the Selsyn motor is
correct, it sounds like that demo where two of those hand-held mini
generators (Gencon's) are connected together. Crank the handle on one,
and the handle of the other will move. Hummm. Maybe the internal
workings of the motors are different, but the functionality sounds


On Fri, 8 Mar 2002, Gerald Zani wrote:

> Hi Liane,
> I was interested in your question so I did a little research. The correct
> spelling is Selsyn Motor. It is mentioned once in the PIRA bibliography at
> 3A75.45, and a tidbit of info can be found in Meiners.
> "A device called a Selsyn was developed about 1925. This comprised of a
> system whereby a generator and a motor so connected by wire that angular
> rotation or position in the generator is reproduced simultaneously in the
> motor. The generator and receiver are also called, a transmitter and
> receiver. About 1942 or 43 the term, synchro, became the general term,
> replacing the word, selsyn."
> The above quote is from:
> I recommend doing a searches on Google, particularly in the groups section,
> and also on alltheweb, altavista, and mamma. You should find some good
> info from the group Group: misc . industry . utilities . electric
> In that group Alun Evans wrote:
> from, "Principles And Practice Of Radar", by
> H.E.Penrose, published by George Newnes Ltd, 1949.
> "The rotors of both the transmitter (generator) and receiver (motor)
> selsyns (or Magslips) are single phase and are both fed from the
> same AC source. The stators are three coils physically at 120
> >degrees to each other, and wired in a Y configuration.
> As the generator rotor is rotated, it will induce (by simple
> transformer action) a voltage in the three stator coils of
> varying value. (something between zero if 90 degrees
> between the coils, to the maximum possible.) Also, there
> is a possibility of 180 degrees phase inversion if turned the
> other way about. The induced voltages from the three stator
> coils is fed on a one-to-one basis to the corresponding coils
> of the motor stator. (There is no connection to the star-point of
> the Y).
> Now, remembering that the two rotors are fed in the same phase,
> the motor rotor will now, by a simple spatial vector resolution of
> magnetic field, align itself to the same direction as that of the
> generator rotor."
> and Larry E. Shambaugh wrote:
> They had the Selsyn motor systems on the USS Taylor- DD468, Fletcher Class
> Destroyers in Built in 1941. I was a EM2 on the USS Taylor from 1960-1964.
> I think I had to work on them a time or two. If my memory serves me
> correctly there were 2 sets of cables, Port and Starboard going to the
> rudder and we could swap to eather control cable if a hole got shot in it.
> At 09:44 AM 3/8/2002 +1200, you wrote:
> >Hi everyone,
> >
> >I am looking for someone who might know where I could get my hands on
> >some selsen motors.
> >
> >I don't have a lot of information on them, but a lecturer here saw some a
> >long
> >time ago, and would like me to make some sort of demonstration for his
> >medical imaging physics students.
> >
> >I believe (and I'm sure others will know much more) that they were used in a
> >"control" and "slave" type of configuration for things like antenna
> >location, or
> >remote digital readout depending upon location of other servo...
> >
> >The lecturer believes they might be used for good hysteresis and
> >motor/generator demos.
> >
> >Any hints/help would be grabbed with joy!
> >
> >Thanks
> >
> >(By the way, my hallway mechanics demo consisted of hanging metre ruler,
> >funny centre of mass toys, and a Mac running clickable mpeg mechanics
> >movies - doesn't look too bad - I know some are not fans of computer demos
> >but it was difficult to make a professional looking pendulum demo that grabs
> >you attention - and the students seem to like it - maybe we don't see these
> >things very often over here though - thanks for the suggestions a while back)
> Best regards,
> Gerald Zani
> ------------------------------------------------------------------
> Gerald Zani e-mail:
> Manager of Demonstrations phone: (401) 863-3964
> Department of Physics FAX: (401) 863-2024
> Brown University Providence, RI 02912-1843 USA
> Do a little more of that work which you have confessed to be good,
> Which you feel that society and your most Just Judge rightly demand of you.
> Cultivate the tree which you have found to bear fruit in your soil.
> If you have any experiments you would like to try, try them.
> Now's your chance.
> Henry David Thoreau, Journal entry, 1850.