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Old 05-12-17, 07:05 PM   #1
modelengineer
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Default Repeater motor

Hi
apologies if this is in the wrong place but Im hoping someone can give me some advice
I have a little "motor" that I want to turn into a generator for one of my model engines
Its called a repeater motor which I think is an early form of stepper motor
It has six coils sround a central rotor, the coils are connected diametricaly opposite each other, at the moment three leads are connected together with the other three to seperate contacts
The rotor is not magnetic and has no windings
I would like to replace the rotor with a P.M and rewire the windings so that I can use it as a dynamo
Is this possible and if so how should the coils be rewired
Thanks in advance
Dougie
Attached Images
File Type: jpg SANY0303.JPG (141.2 KB, 33 views)
File Type: jpg SANY0304.JPG (138.1 KB, 29 views)
File Type: jpg SANY0305.JPG (137.1 KB, 29 views)
File Type: jpg SANY0306.JPG (144.3 KB, 27 views)
File Type: jpg SANY0308.JPG (143.7 KB, 27 views)
File Type: jpg SANY0309.JPG (139.7 KB, 26 views)
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Old 05-12-17, 07:20 PM   #2
listerdiesel
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Looks like what were known as Selsyn motors years ago, very light windings and I'd have thought not too suitable for what you want to do, as the windings will be high impedance and not carry much current.

https://en.wikipedia.org/wiki/Synchro

Lucien may have some more input.

Peter
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Old 05-12-17, 09:40 PM   #3
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Selsyns and other synchro systems have a wound rotor but I have a vague recollection from EMI of a DC remote indicating system called an 'M' transmitter which was a set of cam driven contacts sending current down three lines depending on position, the motor at the other end of the lines would take up the same position so 'repeating' the input to the transmitter.

Either way, unlikely to be much use as a genny.

EDIT; Was beginning to think I'd dreamed it but finally found something on the web about M transmissions! http://www.google.co.uk/url?sa=t&rct...HeCJJLG22H6eby See attached screen shot. Not saying it is definitely one of they but definitely looks similar with six coils and un-wound, un-polarised rotor.

NHH
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Old 06-12-17, 12:59 PM   #4
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I have a "Dynohub" somewhere in "storage" that I was going to use as a generator for "night lights" on an engine. Maybe one of those would be a better bet.
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Old 06-12-17, 01:13 PM   #5
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My initial thoughts were Desynn, Selsyn or Magnesyn, which can have a PM rotor, but Dougie's appears to be star wound? I would think that if Dougie can arrange a PM rotor then he would have a 3-phase alternator, and a bit of rectification should make something useful?

MP
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Old 06-12-17, 03:03 PM   #6
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Thanks for the replies
it was advertised as a 50v aircraft repeater motor, the open ends showing the windings is what appealed to me in the hope I could use it as a dynamo for my models
I may try to wind replacement coils if the originals are not suitable as has been suggested
The suggestion that it may be ok as an alternator sounds good, if I make a pm rotor would a single cylindrical magnet with diametricaly opposed poles or a rotor made from slim rectangular magnets around an arbour be best?
Any thoughts
Thanks
Dougie
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Old 06-12-17, 03:19 PM   #7
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A.P. = Admiralty Pattern. Anyone know if Fleet Air Arm used this type of designation rather that RAF stores / section refs on aircraft parts pre NSN - one for you perhaps Martin?

If you are in a position (or can be bothered) to make a PM rotor, I suspect the best bet would be some of those nice powerful button magnets found in computer disc drives, shaped pole pieces (don't need to be laminated) and lots of epoxy!

NHH
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Old 06-12-17, 03:27 PM   #8
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No idea, sorry. However, no matter what the seller thinks, just because it's a repeater doesn't mean it is necessarilly anything to do with aircraft - ships and ground/shore installations also have a lot of remote indicating. 50V would be a very unusual voltage for an aircraft, and to be frank; it really doesn't look like aircraft quality.

MP
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Old 06-12-17, 04:55 PM   #9
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Does appear to be ship rather than airborne equipment. Here is a Fleet Order referring to the replacement of pattern 1719P motor in connection gyro-compass repeaters:-


"4621.—Commercial Sperry Gyro-Compasses—Bottle Transmitters

(C.D. 407/44.—31 Aug. 1944.)

Bottle transmitters are fitted in connection with many Sperry Mark VI,

VIII and XIV gyro-compass installations to convert the 70 volt Sperry type

transmission from the master compass to “ M ” type transmission at 20 volts

for the operation of additional repeaters and other instruments of Admiralty

type.

2. Until recently, the driving motor of the bottle transmitter has been

repeater motor Pattern 1719P, 50 volt, supplied through three line resistances

of 150 ohms each.

3. Reports have been received from time to time that the outgoing trans*

mission has failed to keep in step with the master compass transmission, and

this failure has been attributed to the torque of the driving motor, Pattern

1719P, being inadequate to drive the transmitter under adverse conditions

of fast yaw in heavy weather.

4. Greatly improved torque, particularly at high speeds of transmission,

is provided by substituting 20 volt repeater motor, Pattern 1730P, again

supplied through line resistances of 150 ohms each, see paragraph 7.

Bottle transmitters installed in United Kingdom for this service in

future will accordingly be fitted with motor, Pattern 1730P.

5. Ships in commission, in which failure of bottle transmitter, Pattern

4356S 50V., attributable to insufficient driving torque of the repeater motor.

Pattern 1719P, fitted in this instrument, has been experienced, should replace

the motor by Pattern 1730P. The work of replacement should be within the

capabilities of ship’s staff assisted if necessary by depot or base staffs or

H.M. Dockyards.

6. The following instructions for replacement are promulgated for

guidance: —

(a) Turn the transmitter until the screwdriver slot in the shaft of the

repeater motor at the outer end is vertical to the base and mark

or note the position of the transmitter shaft or dial.

33

4621

(b) Remove the motor, Pattern 1719P.

(c) Enter the pinion of the motor, Pattern 1730P, into the serrated

coupling of the transmitter shaft, keeping this shaft in its

marked position while the repeater motor shaft is kept in its

vertical position by means of a screwdriver engaging the slot in

the shaft.

(d ) Secure the motor by its three sctews so that the position of the

terminals corresponds to the existing wiring, and connect up.

(e) Check that the transmitter shaft turns freely.

7. Since the current required by motor, Pattern 1730P, is much greater

than that of Pattern 1719P, 1-50 ohms resistance, Pattern 1879, 50 watts, must

be used, and not 150 ohm resistance, Pattern 1880, 25 watts, which would be

likely to overheat. In most instances resistances, Pattern 1879, have already

been provided, e.g., on 7-way repeater panel, Pattern 993, but if not they

should be fitted in replacement of resistances of any smaller dimensions.

Resistance, Pattern 1879, is 3|-in. long, f-in. diameter.

8. Ships concerned should report on the next quarterly gyro-compass

report, S.1177a, when this alteration has been carried out.

9. Since the replacement of motor, Pattern 1719P, by Pattern 1730P

greatly increases the load on the gyro-compass transmitter, this alteration

is not to be made to instruments other than the bottle transmitter without

specific instructions from Admiralty."



EDIT; Sorry, I found it interesting - just the sort of tripe I used to write at EMI!

NHH

Last edited by nickh; 06-12-17 at 04:58 PM.
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Old 06-12-17, 05:52 PM   #10
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I found it interesting as well
I ordered a couple of magnets that will fit snugly into the spaces on the rotor so I will find out soon if I can generate any power, I dont need much, just enough to light a couple of small bulbs
Fingers crossed
The seller also had a quantity of the 20v versions so it looks like you were right on the money Nick
Dougie
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