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Induction coils

Started by Fordtrucksforever, January 23, 2015, 03:35:02 PM

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Fordtrucksforever

January 23, 2015, 03:35:02 PM Last Edit: January 23, 2015, 09:01:30 PM by Fordtrucksforever
Are all or any early type induction coils compatible with common battery lines? I have several Kellogg wooden phones with the No. 28C(corrected old ink on coil) induction coil. Just needing to know if there are any issues converting over to common battery, per the early schematic on those models. IIRC the primary coil reads about 1 ohm and secondary is a little over 50 ohms. These readings are a lot different than in newer phones. Or am I just completely clueless?

dsk

#1
January 23, 2015, 03:56:56 PM
 8) Yes and No!

They are definitely not made for CB lines.  They may still work.  For just speech, but no ringing, the phone will probably work with the line connected to the 2 battery terminals, and just shorting the 2 line terminals.  Ringer needs a capacitor, and this circuit has to be connected to the terminals where the line are connected.  Not a good solution, but it works. 

My best recommendation is to get the book: Old-Time Telephones! by Ralph O. Meyer
Read, and learn!

dsk

unbeldi

#2
January 23, 2015, 04:29:20 PM Last Edit: January 23, 2015, 04:46:04 PM by unbeldi
Quote from: Fordtrucksforever on January 23, 2015, 03:35:02 PM
Are all or any early type induction coils compatible with common battery lines? I have several Kellogg wooden phones with the No. 23C induction coil. Just needing to know if there are any issues converting over to common battery, per the early schematic on those models. IIRC the primary coil reads about 1 ohm and secondary is a little over 50 ohms. These readings are a lot different than in newer phones. Or am I just completely clueless?

No. 23C ?  really? AFAIK, most of the earlier Kellogs used a No. 28C, and think those resistances are about right for the 28.

I am no friend of such conversions, as it destroys the principal character of the device. A magneto phone is supposed to be operating on a dry wire.  You really have to make some technology effort to get those coils to provide a reasonable impedance ratio, by the time you're done, you might as well start out with a CB coil, but are you willing to sacrifice ringing other phones with the magneto? Seems to me setting up a LB-to-CB relay box with automatic ring-down to some number would be much more interesting.

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