Motor, battery or mains please?

[victor.]

Hello All
This is my first posting and its for some help please.
I have this small electric motor that’s part of a 1950’s ish advertising display sign for Butlins with a light and revolving "mirror" disc inside.
I know nil about electric motors and need to firstly test what I have. If its not working I need to repair it rather than a modern replacement.
Firstly the light bulb says 6v. Is that via battery or mains? This fitting looks newer than the rest
I don’t want to damage the motor by connecting to mains.
All advice will be most helpful please.
You can see the sign back that has two terminals for something?
Victor

[Tractorfan]

Hi,
There is some kind of battery box that the motor and lamp are connected to. Maybe it took a 4.5 volt pocket torch battery with two brass strips on the top. I doubt that it would have run for very long though. It's odd that there's no on/off switch.
Cheers, Pete.

[Rubberfingers]

I would think it would run from a low voltage isolated AC source, possibly a 6v bell transformer. It also looks like there is a pair of contacts on the motor assembly that are not connected now, possibly originally to make the light flash. Do not connect this directly to the mains!

[victor.]

Ah Thanks to both of you.

If a battery power will run out perhaps I should try the 6v bell box transformer.

So any idea where I can get one?

Also can I just plug into a standard 6v battery to test it works, fingers crossed?

Sorry to seem so dim its just not my subject...

Vic

[broadgage]

Battery operation seems unlikely for an advertising sign that was presumably intended to run all day.
I also suspect that this was intended to work from a very low AC voltage from a bell transformer or similar. The screw terminals look intended for easy connection of bell wire or other lightweight twin wire rather than for direct connection to a battery.

It is just about possible that it was intended for 6 volts DC from a vehicle battery or similar, for use in premises without mains electricity. Not very likely though as mains electricity was fairly generally available by the time that Butlins started trading.

It looks a bit improvised, and might perhaps be home made in order to display in interesting historical advertising sign in the home, rather than for trade use. The single lamp of very low power would not exactly have been eye catching in say a travel agents office.
I would have expected a commercially produced illuminated sign to have used a mains lamp of perhaps 25 watts or a miniature fluorescent lamp.

Definitely do not connect to the mains !

[Richard]

Hi

The motor looks to be an induction motor, so AC supply, and since the bulb is 6v that's where I would start.

Although, looking again, there looks to be a contact operated by a cam on the motor shaft with 6 lobes, and 6 lobes on the motor rotor, maybe an odd way to run it from DC?, although why would you do that instead of using a brush motor?

Richard

[victor.]

Hi
Yes I agree the bulb looks like a home made afterthought but the sign and case and motor are all original, see the pic with the lightweight foil reflector in place.
Is there any phone type charger I can connect it to or Is a standard 6v lantern battery ok to test it.
Thanks
Vic

[dseymo1]

Apart from possibly a lamp flasher, what does the motor actually drive?
It certainly looks like an AC motor, so you'll need a transformer of some sort.

[Richard]

It looks like its turning the dimpled foil disk.

[Lucien Nunes]

The motor is fascinating, I have never seen one exactly like that. The rotor is laminated, so not likely permanently magnetic, and has no winding, so not induction. This makes it a reluctance motor. There is also the black magnetic shunt.

If driven by 50Hz AC from a step-down transformer, it would run at 60x50x2/6=1000rpm, so that contact spring / cam would impulse at 100Hz and could have no sensible use in the sign. So I think it is an impulsing contact for the motor coil and it would be capable of running on DC. This is similar to the reluctance motor drive of a PO Motor Uniselector which uses the same principle and runs on 50V DC.

I would trace / measure whether the opening and closing of the contact makes and breaks a circuit between the outgoing leads via the coil. If so, I'd try it on a 6V battery. If that works, it might also work well on AC as its rotor is non-magnetised.

Impulse drive from a master clock?

[victor.]

Hello

Oops you have lost me with the tec talk but I am nevertheless very interested and thank you for the comments.
All the motor does is turn the big foil disk, this sits behind a double glass, one with the graphics on and one is a textured obscurer. This must give a great shimmering effect if I can get it working, I guess it turns once every second or two.
I can operate a simple circuit tester and will try your suggestion.
So I can try with a 6v battery as a test and I assume no harm done??
Lastly....anybody near Cardiff??
Thanks
Vic

[Lucien Nunes]

Originally Posted by merlinmaxwell

Impulse drive from a master clock?

No point, it's only to make the background shimmer and seems to want continuous movement rather than 30-sec or even 1-sec steps.

Does it actually need a lamp internally, as the disk is opaque? The torch bulb doesn;t make any sense to me, I think it was front-illuminated or relied on ambient light, hence the dimpled reflector rather than something with a pattern of holes in.

[Lucien Nunes]

Vic, do you have an electrical multimeter of any sort to take a resistance measurement with? If not, and you are keen to try something, first check that the lobes of the little 6-sided cam just lightly brush against the contact spring (this will need to be set to a nicety once it is running, for minimum wear). Offer a 4.5 or 6V battery (or even a 9V PP3 which will have inherently low current output capability) up to the motor leads and see whether any kind of sustained rotation occurs, even if lacking in torque or uneven. I.e. that it turns beyond merely aligning the two of the rotor poles up with the stator. If not, give it a flick. If it still doesn't run, disconnect the battery immediately. There may be mild sparking at the contact. Report your findings...

[dseymo1]

It cetainly won't do any harm to try a 6V battery.
Have a go, and see what happens!
If Lucien's right about the motor, it might need a nudge to start it.

[julie_m]

It looks as though it will need an alternating current to make the motor go round, so a battery probably will not do very much.

[Lucien Nunes]

What specific features make you think it won't work on DC? Do you not think the 6-sided contact cam is an interruptor for the coil circuit?

[McMurdo]

The main motor part looks just like an old Gents reluctance motor on a slave clock, driven off pulsed DC reversing the polarity every other minute. I agree the contact off that tiny cam probably does the same thing. Fascinating stuff. A DC brushless motor! ?

[Tractorfan]

Hi,
Considering its unusual design, I wonder if it was meant to move round in small steps instead of continously?
Cheers, Pete.

[Radio Wrangler]

Looking at the wire gauge out of the coil to one connection lug, I reckon it's a low voltage motor. That ties in with having a low voltage bulb connected straight across the same battery.

Straight across the power source, that bulb isn't going to be flashing, I think it's just to throw a bit more light onto the reflective plate to make it twinkle.

An AC motor wouldn't need an interruptor, it would be much easier to just have a shaded pole job. I agree with it looking like a variable reluctance machine with an interruptor.
The bulb is a give-away for the voltage. 4 large carbon-zinc cells in a package.... maybe one of the old batteries made for electric fences?

Expensive to run, but it must have really pulled the punters in to have paid for itself!

Every time I see the Butlin's name, I think of spoons, now why?... oh yeah, 'Billy Butlins on spoons, and looking very relaxed, a sessions gorilla on vox humana...' Yeah!

David