Electric Edison Home: how can I slow it down?

[Menophanes]

I recently acquired a made-up phonograph based on the superstructure of an Edison Home model B, which was married to a much later electric motor (mains-powered) and fitted into a rather rough mahogany case which I think may once have been a Victorian craftsman's tool-box. I originally bought it purely for parts (it included a complete Model C reproducer), but on investigation I felt it could be made serviceable. The problem is that, unlike the one in the thread http://forum.talkingmachine.info/viewto ... =2&t=30208, the motor had no governor and no evident means of altering the speed, which was much too fast (about 225 r.p.m.). I thought it might be possible to correct this by introducing a rheostat into the wiring. I therefore bought one (rated at 25 watts and 10 ohms, if that is relevant), split the 'live' lead coming from the mains plug, connected one end of this to the centre terminal of the rheostat and the other to one of the side terminals, and switched on. Alas! The phonograph still ran, and not quite as fast as before (about 207 r.p.m.), but it stayed at this speed regardless of how I twiddled the knob of the rheostat. I wonder if anyone can tell me where I have gone wrong? Is the capacity of the rheostat too high – or too low – or is the whole concept mistaken? I realise I should probably quote the wattage of the motor, but it is not marked anywhere and I have no idea how to ascertain it. The mains supply is normal for Britain, 240-volt alternating.

Incidentally, the reproducer turned out to be a later copy. It does work, however.

Oliver Mundy.

[briankeith]

Maybe swap out the motor for an Edison Econowatt motor used in Edison dictation machines ??

[Chuck]

It needs more resistance.

10 ohms is not nearly enough.

The typical wire-wound variable resistor found
in Dictaphone shaving machines has a range
from zero to about 600 ohms.

Running a typical universal brush-type motor
on 120 volts alternating current, 60 cycles, I have found
that when the rheostat is set at about 280 ohms the
motor barely starts and turns very very slowly.

So, I'd say get a rheostat that has a total available
resistance of at least 600 ohms. That should assure
you a motor RPM from zero to full speed.

You'll need much more than the 280 ohms I mentioned
because you are in the UK on 240 volts, where as I
am talking about 120 volts in the USA.

I think I'd also want to work with a larger rheostat
with more power dissipation capacity.

At only 25 watts, it may start heating up rather a lot
when a good share of it is in the circuit.

If you can find about a 100 watt, 600 ohm rheostat,
that will probably work well.

Or....as an experiment, you could start putting
lamp bulbs in series with your motor to see how
much that slows it down. I'd start by putting
a plain 100 watt bulb in series and see what the RPM
is. Perhaps a combination of a few lamps and your present 10 ohm rheostat all in series with the motor
might get it where you want it to be.

Try that.

[phonojim]

You could also calculate the pulley ratio needed to bring the speed down to 160 RPM. If you don't already have one, I recommend that you purchase a laser tach. They are widely available on ebay, they are cheap, easy to use and I consider mine indispensable. Since you know the required mandrel speed, you can measure the motor speed and calculate the size pulley needed on the motor. If the motor already has a very small pulley you would need to use an intermediate shaft and two more pulleys to achieve the desired ratio since the mandrel shaft pulley can't be changed.
It may be helpful if you could if you could supply some pictures.
I just read Chuck's post and, as he said, that will work to a point if you have a brush type (universal) motor. However if you have an AC induction motor, lowering the voltage is not the way to control speed. Their speed is dependent on line (mains) frequency and, to a far lesser extent voltage. Operating the motor on low voltage may cause it to overheat and lose power, so this is not a good idea. If you have this type of motor it will start up very quickly and maintain speed very well, but you will need to work with the pulley ratio to achieve correct speed.
If you have a universal motor, rather than using resistance, which lowers power, causes slow startup and creates a lot of heat, I would advise looking for a regulated variable voltage power supply which would do the job more accurately.
Before you try anything, check the motors nameplate to see whether or not it is AC only or AC/DC. Somewhere on the plate it should say something like "220 volts, X amps, AC/DC" or "220 volts, X amps, 50 cycles (or HZ), AC (only).

Jim

edited 1 time 5.8.17

[epigramophone]

If this machine was Lot 225 in the SAS sale on 22nd February I remember it well, as I assisted the family of the deceased former owner with sorting through the many machines, accessories and records (which occupied two rooms) ready for collection and cataloguing by the auctioneers.

The machine as found had no reproducer or horn, but among the large quantity of odds and ends I discovered these items. My electrical knowledge does not extend much beyond replacing a light bulb, so after a quick look at the wiring I decided in the interests of self preservation not to try the motor!

[Uncle Vanya]

An electric motor without a governor will not regulate worth a tinkers dam. You really should look for a motor from an old Ediohone dictating machine , or even a motor from a cylinder Dictaphone. These units are not expensive, and should cost but 10 or 12 guineas if one must pay for one at all.

[Lucius1958]

These units are not expensive, and should cost but 10 or 12 guineas if one must pay for one at all.

Wait a minute: are guineas still a thing at all?

Bill

[Menophanes]

Thank you all for your suggestions. I shall give some photographs below, and I hope somebody will be able to establish from these whether the motor is of the 'brush' or the 'induction' type or else tell me how to do so. As I understand from phonojim that the possibility of using a rheostat depends very much on this question of motor type, I shall not take that idea any further until the type is determined. I still cannot find any identifying plate or marks on the motor.

The crude windmill or fan on the small flywheel of the motor is another idea of mine for lowering the speed; I thought I could perhaps create enough air-resistance by this means to bring the revolutions down to the correct level. This actually works in principle, reducing the speed from 207 r.p.m. (which was all I could manage with the original small rheostat) to 192 r.p.m.; but it is too small to make enough difference, and there is too little room inside the case to make the fan any larger.

I should not like to mutilate an Ediphone or Dictaphone for the same of reviving this curious but quite unimportant machine of mine. Those later cylinder dictating-machines may be regarded as expendable now, but who can say how collectors' tastes may change twenty or thirty years from now? Besides, they seem to be very much less common here in Britain than in the U.S.A.

If the rheostat is a dead end, enlarging the pulley on the feed-screw shaft may be the only way forward. I know even less of metal-work than I do of electricity, but I could probably increase the rim to the necessary diameter by building up a 'tyre' with strips of cardboard glued (lightly, so that they could be removed in future if need be) to the existing wheel.

Guineas effectively vanished from the British monetary system in 1971, although I believe dealers in racehorses, antiques etc. may have continued to use the term among themselves for some time afterwards. One guinea equalled one pound one shilling, or GBP1.05 in modern terms.

Oliver Mundy.

home_02.jpg (39.7 KiB) Viewed 2200 times

[Chuck]

Looks like it could very possibly be an induction motor.
This is because I see no brush holders and also
the laminations can be seen.

If it is indeed an induction motor, then the only
way forward will be to mechanically reduce the speed
via belts and pulleys.

[startgroove]

First, let me say that I think this project is worth pursuing. An electric powered Home is a great convenience to someone who like to listen to numerous cylinder records in succession.

The motor you show is not a regulated motor, at least not in the conventional sense. For several reasons, it is not suitable for what you want to do, the main reason being that there is no simple way to keep the speed constant under varying load.

Several people have recommended using an Ediphone or Dictaphone motor that is governor regulated. In my opinion that is the best option, considering cost and ease of adaptability. Neither of those motors care about line frequency, but they do care about voltage, so choose accordingly.

Good luck!