Western Electric Induction Coil No. 13 connections

[MagnetoDave]

More good news!

In a spirit of "let's just try it and see," I wired L1 and L2 of the magneto telephone into the L1 and L2 of the network block of my Model 500, so that that the magneto phone acted as an extension.

To my delight, when I picked up both receivers, both off hook, I could hear the dial tone in both the receiver of the magneto phone, and in the Model 500! I dialed the 500, and had a slightly strange phone call where I listened with the century-old receiver of the magneto phone, and spoke into the 50 year-old transmitter of the Model 500.

So it looks like the secondary winding of the coil is OK!

Next step is to troubleshoot the transmitter circuit. I verified that the transmitter itself is functional (by wiring it into the Model 500), so I just need to double-check the wiring, my batteries, and the primary of the induction coil.

[MagnetoDave]

Success! It is fixed!

I just got off the phone a minute ago.... off my Western Electric magneto phone!

It turns out that the problem was two wires on the induction coil: one wire on the PS side was broken, and one wire that should go to the Primary side was missing. I fixed and replaced those two wires, then got a power source for the transmitter (a super-nasty unfiltered AC-DC 12v wall plug) and connected it to the battery wires.

There's a crazy lot of noise in the circuit from the unfiltered power source, but I had a successful phone call. So my next step is to get batteries for this and then build a proper modular phone line connector for it. I also need to add a condenser in series with the ringer.

Then finally I'm going to be looking into options for adding a dial to it.

Thanks, RB, for guiding me toward the solution!


(I think what I find most impressive about this entire exercise is that, to the best of my knowledge, the telephone is wired the same as it was over a hundred years ago when it left the Western Electric factory. I've made no internal wiring changes, nor have I added any additional circuitry in between the L1 and L2 terminals in the phone, and my phone line coming in.)

[RB]

Congrats, Dave!!!
Dials are easy, only 2 types, and both would work for you.
Condensers are avail from electronics stores, no need, "unless you just have to have orig" to pay for an old one.
Good luck with it!

[MagnetoDave]

I just got Mountjoy's book at my library this morning. Wish I'd had it 2 weeks ago.

Note to future readers, owners of type 232:

The schematic for the Western Electric Type 232 can be found on page 56 of "100 Years of Bell Telephones" by Richard Mountjoy. The schematic shows where to insert a 2 MF condenser (capacitor) for common battery use. It involves cutting a wire from the hinge.

[Jim Stettler]

Richard Mountjoy's book is one of my favorites. It is the most informative of the color picture telephone books.
Jim S.