Western Electric Induction Coil No. 13 connections

[MagnetoDave]

I have a Western Electric Type 232-E local battery/magneto telephone. The induction coil is not properly connected to the rest of the telephone circuit, and I'm not able to locate enough information to determine which leads on the coil should be connected to which binding posts.

There is one unattached lead on the right side (see photos) and one broken-off at the block (and hence, unattached) lead on the left side.

Would greatly appreciate it someone could provide some clear photos showing their No. 13 coil in the circuit -or- a photo or clear description showing where the primary and secondary leads are.

Here's what I've got so far. The black S, P, and PS are stamped in the wood. The receiver connects to the two brass screws at the bottom left of the box. I can take more photos if requested.

[RB]

It looks like your leads have broken off the coil...
It may be unusable at this point???
The wiring is P=Xmit, and S=receiver circuit.
What is this thing connected to?
You may be better off finding another induction coil.

[MagnetoDave]

It looks like your leads have broken off the coil...

Yep. The one on the left side is definitely gone, but if I poke my test probe in there, I can establish contact. Problem is, I don't know if it's a primary or secondary connection. I think it can be refurbished, but I need to know more about the coil.

What is this thing connected to?

Right now, there are only two established connections. Both are from leads on the right side of the coil. One lead goes over and across the coil, and is connected to a binding post marked S for the receiver.

The other connection goes to the binding post marked PS on the side wall of the box. The wire leads to the switch hook, and is ultimately part of the transmitter circuit.

I drew out the schematic by tracing all the wires. I can find no published schematic for the model 232-E.

[RB]

Here is a schematic of what you prob have there, the one on right is easier to follow.
The P=primary, or transmitter and the S=secondary, or receiver.
Most Sidetone Local batt types follow the same basic diagram for your coil.

[MagnetoDave]

Here is a schematic of what you prob have there, the one on right is easier to follow.
The P=primary, or transmitter and the S=secondary, or receiver.

Thanks, that helps. I see that in the schematic, the right side of the induction coil has P and S tied together. My next question is: should there be just 3 leads coming to/from my coil, or 4?

Because I'm looking at other photos of coils, and I see some with 4 contacts, while others seem to only have 3.

[MagnetoDave]

Here are photos showing the left and right sides of my induction coil. I have no idea what any of the connections are, primary or secondary. I can find no markings on the coil itself, other than "65" stamped on top and "No 13" stamped on bottom.

Can anyone help me identify the connections on my coil?

[RB]

Dave, look at these.
I have not seen a coil with wires sticken out from it, but looks like it may be salvageable??
The schematic I provided will be the same as your wiring. use one on rite side.
verify if these connections are solid, or broken, and we can re attach them, and I bet it will work

[RB]

I found this too. looks same?

[MagnetoDave]

I found this too. looks same?

Yeah it does looks similar, but the out-of-focus photos are really frustrating. I asked the seller if he could take some in-focus photos, and he responded by uploading more blurry photos! 

[MagnetoDave]

Dave, look at these.
I have not seen a coil with wires sticken out from it, but looks like it may be salvageable??
The schematic I provided will be the same as your wiring. use one on rite side.
verify if these connections are solid, or broken, and we can re attach them, and I bet it will work

Regarding your first photo where you wrote "Broken wire?": that green wire is wrapped around the block. It appears to have been made that way.

Now your second photo where you wrote "Is this attached?" and then "or did it break from here?": you hit the nail right on the head! Last night I did some more investigation. I noticed some green insulation remnants at the base of that white cloth cover (remnants visible in my photos). I decided to remove the cloth cover and this photo below shows what I found.

The green-covered wire that was sticking out was in fact broken, and should have gone through the white cloth cover to match the other side of the green wire, as you guessed. Both the green and white wires are supposed to go to the PS binding post.

That accounts for three connections on the right side: primary, secondary, and secondary. That left the lone connection on the left side, where the wire had broken off inside the wood block, as the other primary connection. So I believe I have now identified all 4 connections on this coil.

But here's the kicker: with the coil now out of circuit, I measured its resistance across both primary and secondary, and found a little over 0 Ohms for both. This smells like a short-circuit to me. And so it looks like I'm not out of the woods yet.

[RB]

Primary side shud be only a few ohms, but secondary, shud be 14 or more about that anyway.
The broken wire on the left sitd top middle? can you access that wire from the back side of the block?

[MagnetoDave]

Primary side shud be only a few ohms, but secondary, shud be 14 or more about that anyway.

Well I got the same almost-zero reading on both pairs. :-(

The broken wire on the left side top middle?

Yes.

can you access that wire from the back side of the block?

Maybe. I'd probably have to strip the cloth insulation from one of the wires that is wrapped around the end of the block.

But here's what I did in the mean time. I took a new wire, tinned the end with my soldering iron to make it fatter, and stuck it in the hole so it makes contact with the broken-off copper wire already in there.

This wire connects to a binding post marked P on the right side of the coil, near the PS binding post.

I also have the receiver connected to the two brass screws in this photo.

[MagnetoDave]

Well I got the same almost-zero reading on both pairs. :-(

This may be a measurement error. I'm using an analog multimeter, and according to Ralph Meyer's book:

Many older multimeters have a single k-ohm (1,000-ohm) scale for resistance measurements, with the smallest division on the scale being 100 ohms. This type of meter is not adequate for telephone work because coil resistances, which will have to be measured, are in the range of a few ohms.

So I need to take a second look at my meter to see if this is the case (probably it is), and then I'll need to get another meter and take the measurements with it.

So I'm crossing my fingers that the coil is good, but it's just my multimeter wasn't able to accurately measure its resistance!

[RB]

A  pic, and questions for clarification.

[MagnetoDave]

A  pic, and questions for clarification.

Answers:

Q1) Is this wire attached here?
A1) Yes, and that wire goes over to the binding post marked S, which is a connection for the receiver.

Q2) Is green part a wire?
A2) Yes it is a wire wrapped in green insulation. That wire was broken when I received this telephone.

Q3) Is this attached?
A3) No, not at the time that picture was taken. That white wire broke when I removed the cloth wrapper.

Both the broken green wire and broken white wire I repaired last night. They both terminate at the PS binding post. To the best of my knowledge, the green is primary; the white secondary.

It may be that my analog multimeter is not able to accurately measure the low coil resistances. I am going to get another meter, probably a digital one, and take the measurements with it.

Confirmed: My ohmmeter is on a 1K scale, so I need to get another meter. This coil may be good after all. We shall see.