Motor, battery or mains please?

[Lucien Nunes]

There seems to be something of a cult for making the electronically-commutated motors illustrated in the website you link Lee. Although they are reluctance motors, they differ from Vic's motor in having permanent magnet rotors. DIYers construct them from scratch or modify small DC fans and seem to get endless fun from discovering that back EMF can be used to charge a battery at a higher voltage than the supply. There is a notion that it is a recent and revolutionary concept, as the constructors are often unaware that flyback supplies have been used in televisions more than a few times, and that reluctance motors and sensorless electronic commutation are also well known to electrical engineers. In the process, when attempting to measure currents of arbitrary waveform with a DMM, they sometimes obtain surprising and erroneous results that can appear to violate well-known physical laws. Although Vic's motor is very unusual and interesting in execution, its method of operation has been in use for a century or more and has had its moments of fame, for example in the high-speed PO motor-uniselectors driven by a rotary single-coil reluctance motor instead of the step-by-step self-drive of a conventional ratchet uniselector.

I did not see the contact set under the spring. That is a better arrangement than relying on the contact with the cam, although it requires slightly more force to operate. Thus, there should be continuity from the solder tag to one contact spring, through the contact points when closed, and from the other spring to the frame. There are probably insulating washers between the springs that prevent one of them contacting the other or the screw. Vic - check this over, make sure the contacts are clean, check on 200 ohm range for continuity from one spring to the other when closed, it should be no more than a few ohms.

[Hunts smoothing bomb]

I was looking at this more in depth this afternoon Lucien and it looks as though that the washer assembly on the contact set may have been altered at some point as the solder looks messy, I can't see any insulating washers either which would pose a problem as this would mean that the coil would be energized at all times regardless of the cam position which would mean the motor will not totate.

Cheers

[victor.]

Hi All
Tony, you are correct it is 0 ohms between the other tag and the brass contact that touches the hex cam.
The "contact points" at the start of the brass arm are not in fact points. It is an adjustable screw system to fine tune the position of the brass contact arm against the hex cam.
I have now adjusted the arm to get what I believe is the desired on/off contact between contact arm and hex cam. I have tested this with the meter and can confirm this is operating.
Just as a test I have connected to the 6v battery and given a nudge, nothing I am afraid.
You have mentioned a spring to make a contact with, what is the spring?
Is it the brass contact arm? Thanks again.
Vic

[TonyDuell]

I was assuming, as others did, that the hexagonal cam made contact with that brass arm, and that that was the switch rather than there being other contacts. Actually, I am still not totally clear as to exactly what goes on here.

So now, if you turn it by hand do you get the 1100-or-so ohm resistance when the cam operates the contacts and open circuit (often shown on the meter as a 1 on the far left of the display) when it doesn't?

[victor.]

Hi Tony
Sorry if I am not clear. I have assumed that the hex cam should make contact with the brass arm six times as it rotates once. I have set it to do this with the adjustable screw.
Do you think this is correct?
I will test the resistance tomorrow and report back....thanks for your patience.
Vic

[Lucien Nunes]

I have tested this with the meter and can confirm this is operating.

Good. Now we come to the issue of the coil resistance. 1176Ω seems too high for 6V. The current would be a mere 5mA and the power, given say 50% dwell, only 15mW. If that resistance is correct, and it might not be if the coil is damaged, I would think something more like 12-18V as a minimum, depending on the mechanical load. At that resistance, trying a higher voltage will not damage anything as the power dissipated will be very small. As we don't know what the original power source was, it's difficult to say what a typical voltage would have been.

Have we yet confirmed how many leadouts there are from the coil? I was suspicious about the connection to the frame having more than one. What's at the solder tag end? I wonder whether the resistance we are reading is not the whole story.

[victor.]

Hi All
some bad news.
The coil right cheek has just one wire from the tag. This wire goes into the coil at the top, there are no other wires into the coil on that side.
On the left cheek there are the two wires, the one from the centre goes to the frame, the one from the top.....I have today noticed this one is broken, it again goes to the frame but is in two bits and has been through the test measurements I gave.
Its very delicate, I could try winding together but potential trouble.
I am rather stuck with this now??
Regards
Vic

[Lucien Nunes]

It is interesting to speculate what the three ends are. Or two ends and a tap, and why two are from the outside of the coil and one from the inside. It is just possible that the broken wire is not technically part of the coil but a non-inductive resistance; I have examples of electromagnets suppressed with a resistive overwind paralleled with the coil proper.

So long as there is at least 1/4" projecting from the coil, it should be possible to connect to it. If it is silk covered, unwind the silk. If the wire beneath is tinned (silvery) or bright copper, it should be possible to joint without disturbing it further. If it is enamelled then it may need to be scraped or rubbed with fine emery to remove the enamel to get a connection. You might like to test the resistance from here to the other end of the coil, just to make sure it's electrically continuous before trying to solder it. It's OK to pinch the wire against the meter probe with your fingers because at the resistances under consideration the conductivity of skin is too low to affect the reading.

If it gives a useful-looking reading, I'd solder it either to the stub or perhaps better to a piece of clean bright copper wire of similar gauge attached to the tag in its place, to maximise the chances of getting a good connection to the coil end. Use traditional 60/40 flux-cored electrical solder, not lead free, as the latter requires higher temperatures and is more fussy generally.

[victor.]

Hi
Well I will be going beyond my skills, Soldering?? I can give it a try after practice. I will take the readings first.
This will have to be next weekends job.
Thanks
Vic

[thermionic]

Victor. We have speculated on the operation voltage, 6 Volt, 12 Volt, Etc. Could you look at the voltage marked on the small screw in lamp to ascertain what is marked on it? This would be a good clue.

Good luck with this, such an unusual item .


Cheers. SimonT.

[Tractorfan]

Hi,
According to post no.1 it's a six volt lamp, but it looks a bit of an afterthought so may not be the correct one.
Cheers, Pete.

[dseymo1]

If there are three wires from the coil, I wonder if it forms a sort of autotransformer to run the lamp (I suppose there must have always been a lamp of some sort)? It would certainly add to the 'shimmering' effect, as the voltage varied with the motor flux.

[victor.]

Hi All
Thanks for the help.
I have not been able to respond lately however I will add some more info over Easter.
Regards
Vic

[Hunts smoothing bomb]

I was following this with some interest, did you manage to find out anymore Vic?

Cheers

[marleykente1]

Hi Victor,
i have also have the same sign by VIBRALUX although mine is advertising for Lemon Hart Rum. Mine Has a gentleman pouring rum into a glass and his hat, glass jacket and the bottle all shimmer when it is running. I run mine from a battery and it works fantastically. I opened it up today, which I have never done before! In the interest of your enquiry I wanted to see if mine had a light bulb inside like yours, and can tell you that it does not, and never has had. I hope that helps you with your investigation?
Cheers

Nev

[Lucien Nunes]

Hi Nev

Thanks for joining the forum and posting about your sign. As you'll see from the thread above, some of us here have been intrigued by the unusual way the little motor works. Might I ask:
Does your motor look the same as Vic's?
What voltage battery do you run it on / does it specify?
Any chance of some pics inside and out?

We suspect a coil in Vic's motor might be faulty. If we pick up the thread of troubleshooting, do you have an electrical multimeter and would you be willing to take a couple of resistance measurements on your motor, so we know what it should be?

Lucien

[victor.]

Hello All
I am rather guilty of letting the thread drop. I am just as keen to get the sign up and running but more pressing things had taken my time.
A big thanks for all who have been trying to help me.
I see marleykente1 has a similar designed sign. This may be the answer to all my problems.
Please will you be kind enough to look at the motor, is it as mine?
Your sign sounds great, any chance of a photo please?
Regards
Vic

[Billy T]

Just a thought:

I have no knowledge of such motors, but if the coil (dc) resistance is >1100 ohms, then at 6 volts / 5.5-6.0mA input, the 'power' available would be in the range of 35mW.

The question I pose is this:

"Would that current level be adequate to operate the motor in whatever mode for which it was intended?"

Cheers

Billy

[Mad Mal]

The battery box looks like it takes either a 6V Lantern battery (these have thumb screw terminals and would be connected to the contacts by wires) No idea as to polarity. The bulb looks like a later addition as marlekent1 said the disc used reflected light to make the effect. Someone added the bulb at a later date, probably to make the sign visible at dusk or night, May possibly have been an advertising installation in a Travel agents perhaps. This is the kind of battery I think it needs...https://images-na.ssl-images-amazon....SR262,320_.jpg