Kellogg wall phones - need help

[ct92404]

Hi all,

I realize this is a European website and people here might not be too familiar with antique American telephones. But I've had a lot of help here with other projects, so I thought someone might be able to give me some advice.

I recently bought an antique wooden telephone. It doesn't have a dial and uses a crank generator and a battery. It's in really good condition, and all the parts and original wiring seem to be intact. (It even came with an original vintage "dry cell" battery!) Unfortunately, I haven't been able to find much information about it. I found a company name on the handset - "Kellogg Switchboard And Supply Company." But so far, that's all I know. I haven't been able to figure out a model number or when it was made. Based on some pictures I've seen online of similar phones, I THINK it was made around the early 1930's.

I took out the generator ("magneto"?) to clean it and then put it back in and reconnected it. But I'm not sure if I connected one of the wires right. There are 3 screw terminals where wires can be connected. The lower terminal with red wires was easy, but there is another green wire that is supposed to be connected to one of the other two brass terminals. I'm attaching a picture of the connection, which I hope will show up clearly. When I crank the magneto, the bell on the phone rings. I don't know whether it's supposed to do that, or if it means that I connected the wire wrong on the magneto. (I would think that only a receiving telephone should ring when you turn the crank to make an outgoing call). I don't know anything about how these telephones worked. Actually, I don't really know much about how phones work in general!

Then a couple of days ago, I got really lucky and found another antique wooden phone! I'm pretty sure they're the same model. The cabinet and internal parts looks identical. But someone has really messed with the 2nd one. They changed the handset and rewired it at some point, apparently to try to make it work with the modern telephone system. My plan is to fix it and put the wiring back to the original condition. I think it would be cool to hook up the phones together to be able to talk from one to the other, if that's possible.

I'm also attaching a picture of the inside of the 2nd phone. You can see where original wires have been disconnected and extra wires where other parts had been added at some point to try to make the phone work with a modern phone network. I took out the extra parts, but some of the wiring is still there.

So my questions are:

- Around what time period would these phones have been made?

- Is the bell supposed to ring when I turn the crank, or did I maybe hook up the magneto wrong?

- Is it possible for the 2nd phone to work with that modified handset but otherwise using the original parts? I do want to replace it with the "correct" vintage one later, but I just want to see if I can get both phones to transmit to each other.

I'm sorry this post is so long! But I really appreciate any help anyone can offer!

- Chris

[dagskarlsen]

Hi. You do have 2 so it shall probably be equal. A close picture of the wiring diagram on the door would also help us to help. A close picture of the contact springs and and terminals on the generator might be good too. Generally these had 3 terminals, where sometimes only 2 was used. The hone closest to the magnets are connected to the chassis of the generator, and this was usually connected to the line terminal named L2, the middle one was connected to the Ringer, and the last to L1. With this solution the calling telephone has a silent ringer to let all the power go to the callee.

Photos may help us to find the exact model of your phone.
(Here will the visible text on the components an schematics on the door be of importance.)

dsk

[Dave Moll]

The internals of the two 'phones (and the wiring diagrams as far as can be seen from this distance) do indeed look identical. As they are powered by local batteries (a standard "D" cell will be a suitable substitute for the orginal - which is probably best kept as a display item as a lovely example of a period cell), they should be possible to connect together to communicate with each other.

As Dag says, a close-up image of the wiring diagram pasted to the case should provide the information needed to connect them up.

Depending on the type of transmitter (microphone) in the modern handset, this should be fine for getting the 'phones working. The original handset would have been of the carbon-granule type which varies its resistance according to the pressure waves of speech. As long as the modern one works on the same principle (rather than a magnetised coil that generates a small varying voltage) you should be OK, though the modern electronic (electret) substitutes for carbon-granule transmitters will require a minimum of 4½V (e.g. three "C" cells) rather than the 1½V supplied by the single cell.

Regarding the bell ringing when you operate the magneto, this may mean that you have the magneto output feeding back to the internal bell rather than to the line to ring the remote bell. Again, the wiring diagram should help to sort this out.

By the way, what's hiding behind what looks like a brown paper bag?

[ct92404]

Thank you for the replies so far!

I took a picture of the diagram, and I'm also attaching what I hope is a clearer picture of the terminals on the magneto. In about the bottom center of the picture, you'll see a pair of red wires connected to a small screw terminal (the wires are kind of coiled up). I'm pretty sure I have that connected right. But a little higher up, there is a green wire connected to one of the larger terminals. This is the one I'm not sure about. There are two terminals there, as you'll see. I'm just wondering if I might have the wire connected to the wrong terminal. Unfortunately, I can't use the other telephone as a guide because the original wiring has been tampered with.

I found terminals marked "L1" and "L2." I hooked up a multimeter to the terminals and cranked the generator, and it measured about 70 volts AC! That's enough to give a nasty little zap!
It also means that the current from the magneto is getting to the terminals where the phone line would be connected, but I'm still not sure if I connected the magneto right.

The "paper bag" is actually a folded up piece of paper with simple instructions for how to connect two of the phones together. I got REALLY lucky with this antique phone, considering all the original stuff that came with it! I'll attach a picture of the paper too. This is actually why I decided I want to just have the phones have their original circuit, instead of trying to rewire them to work on the modern phone network. (I REALLY wish someone hadn't messed with the other telephone).

[dagskarlsen]

If you have got 70 volts an the line with receiver in on hook posision the magneto is right. The internal ringer should ring when you crank the magnot according to that diagram. White and red to one terminal, green to another on the magneto, the third terminal is not in use. When you go off hook, the crankig should be harder, and you should hear it in the receiver. The old transmitters (microphones) was not depending on polarity, and worked well on 1.5-4.5 Volts depending on the make. For electronic replasements , the voltage may be higher, and poarity may matter.

I,m not sure of the model, but this one has an Anti-sidetone circuit, and those were late at North American magneto telephones.

[Dave Moll]

It all sounds very hopeful. If you ensure that the second 'phone is wired up the same as the first, then connect the two together (L1 to L1 and L2 to L2) operating the magneto on one should cause both sets of bells to ring.

If that is OK, I suggest connecting one or more 1½V cells to the battery terminals of each 'phone and see whether sound into one transmitter (microphone) can be heard in the receiver (earpiece) of the other. If so, congratulations, you have a working system.

[ct92404]

On the better telephone, when I pick up the handset and crank the generator, I can hear pulses on the receiver.

It's probably going to take me a while to compare the wiring and get the 2nd phone wired back up correctly. It's kind of confusing. I really wish the diagram was an actual electrical schematic. I'll go through it slowly and carefully and see if I can get it figured out.

[Dave Moll]

One thing I don't quite understand is the switch operated by turning the magneto. In the rest state it appears that the magneto coil is shorted out - which may be fair enough - but the upper contact of the coil does not appear to be connected to anything other than the one shorting it. I am clearly misunderstanding what the diagram is telling me, but would appreciate some help here.

[dagskarlsen]

You are probably understanding this right. It has been made 2 systems used on magneto phones, both has the generator and a switch operated by the moving of the handle.

Some telephones used a shorting system where you did put the generator in series with the ringer across the line. In rest position the generator was shorted, when cranking the ringer was shorted. It looks like this principle is the generator used here, but the contacts are used different so the generator is disconnected util you crank it, then the ringer are just across the lie all the time.

The other system used the switch to connect either ringer or generator, if you put the ringer permanently across the line, the function will be equal.

I have to look for some schematics, and edit this message.


dsk

Shunting (Elektrisk Bureau) http://www.classicrotaryphones.com/f...ch=67816;image
Switching: (US Army EE-8) http://www.kadiak.org/tel/ee8_1.jpg

[Dave Moll]

The point I was making, though, was that I can't see what the magneto coil is supposed to be connected to while it's being cranked.

[dagskarlsen]

Originally Posted by Dave Moll

The point I was making, though, was that I can't see what the magneto coil is supposed to be connected to while it's being cranked.

As I read this the diagram the contact spring marked B is normally in contact with C and changes over to A when the inductor is cranked.
The Inductor is shorted and isolated from L1 until the cranking, then the short is removed and L1 is connected.

dsk

[dagskarlsen]

Please forget my answer in # 11 It is more or less wrong! The schematics does not look right, and we have to guess. What we want is a inductor who is disconnected unless it is cranked, when cranked it shall put voltage across the line!

dsk

[dagskarlsen]

So my guess will be that it should have been something like this:

[ct92404]

Dave, that's exactly what I was confused about too! That part of the diagram didn't make any sense to me. It does look like the armature is shorted when the generator isn't being cranked. Actually, that whole diagram is pretty bad in my opinion. It's confusing. I really wish they had used a standard electrical schematic. I don't know if that's normally done with circuits in telephones, but it would make things a lot easier.

With dagskarlsen's edit, it makes a bit more sense. A red and white wire are connected to one end of the armature coil. The white wire goes to the ringer bell. When the switch on the generator is closed, the current goes through the green wire to the other side of the bell. So the circuit is then completed and the bell rings. I don't know for sure if this is how the generator is physically connected on the actual telephone, but at least it makes more sense. The only thing I'm a little confused about is that when the generator is at rest, there is another set of contacts that are normally closed. What would they be for? When you turn the generator, a spring causes the shaft to move outward, which opens the first contacts, but closes the other switch to send current to the bell ringer (and I'm assuming also sends the power to the output lines to make the other remote telephone ring). What would the first contacts be for? Does that maybe have something to do with the unused screw terminal? Maybe there is an another optional way you could connect the generator?

The other possibility that just came to my mind is that maybe the generator IS shorted or bypassed until you crank it, so that if an incoming ring came in, the power isn't wasted by going into the armature. That would be a huge load and there probably wouldn't even be enough power left to ring the bell. (Or maybe it would cause the generator to turn like a motor!)

Dagskarlsen, is this what you were thinking? That maybe there was some kind of bypass mechanism to take the generator out of the circuit until it's cranked?

- Chris

[dagskarlsen]

Chris, I agree in your opinions, Telephone schematics has been made after local standards, different not only from country to country, but even from make to make. I tried to sketch up how I believe this i meant to be. I did use symbols used in Norwegian schematic from the 50'ies.

Regarding the inductor you have to measure out and make the diagram yourselves, this is my guess based on experience of what was common in the US around WWii. This kind of generator/inductor could have one end of the winding to frame of the generator, the other comes out of the end of the shaft close to the switching contacts, maybe in direct contact to one. I took some pictures of an old magneto from the same time, this one has been in a Norwegian phone, and will probably have a slightly different switch.

I'm not sure about the make, does the induction coil on the door has any text?

dsk

[Dave Moll]

I'm glad it wasn't just me failing to understand the diagram. I agree that Dag's modified version would make more sense. Perhaps what is needed is some resistance measurements between the contacts on the magneto - both at rest and off-normal (i.e. with the magneto handle away from its rest position but not turning!) The latter may or may not work depending on how the magneto switch operates.

Incidentally, the switch of the GPO magneto 26N/26P works to make the magneto electrically invisible when at rest, but with the handle off-normal (I don't think it needs to be turning) disconnects the local end and connects itself across the line to send its ringing current.

[dagskarlsen]

Thank you Dave! You are more skilled than me on this, I have learned almost everything by my-selves, trying, failing, measuring, comparing, and discussing on internet when that became common. On the magneto pictured in my post, it will be enough to press the crank shaft in, on the German field telephones (FF-33), you need to pull, but the switch will operate without turning the handle. I guess the common resistance of the generator winding will be 300-500 ohms.

dsk

[radiotechnician]

The object of the switch on the magneto shaft is to connect the
armature to the outgoing line. Otherwise it would form a lossy impedance.

The other object of the assembly is to wind a spring, that starts the
armature spinning. Without it, wear on the gear assembly would result
breaking free from where the magnet is holding.

Keep in mind, the magneto is also a signalling device, so smooth action
is needed when sending two short, and three long rings, which will be heard
by every phone on the line. Only the called station will pick up. Never the less,
everyone will know who is calling, and one may even pickup, with some news.
Such as, they have gone for a few days. Such is the charm of that system.

The term for overhearing 'on the line' was rubbernecking.

In Canada, magneto phones were used right to the 60's. Some were even
fitted with dials, so they could operate in areas served by dial and magneto.

A good book is:

Old Time Telephones, by Ralph O. Meyer. Tab Books.

[ct92404]

Dags, thank you for drawing that schematic! That definitely helps!

I had another quick question - in general, how reliable are the capacitors in these old telephones? Should I replace it? When I've worked on antique radios, I usually had to replace several capacitors, especially electrolytic filtering ("smoothing") caps and wax ones. If I do replace the capacitor, I'll leave it installed for historical purposes and just clip the wires and put a new cap across them. But should I bother with that, or do you think the original capacitor might still work?

Oh, and I just tested the ringer. I hooked up one telephone to the other...when I cranked the first one, the bell rang on them both! So at least I'm getting there!

[dagskarlsen]

Usually the capacitors are working for 100 years, this one has only on purpose, if you forget to hang up you drain your battery, but other parties are still able to ring, because the capacitor has a high resistance for the ring-frequency, but lets voice frequencies pass relatively easy. If the capacitor is bad, just strap it.

I am still curious about the printing on the (transformer) induction coil.

dsk