View Single Post
Old 14th Feb 2018, 11:31 am   #23
dagskarlsen
Heptode
 
dagskarlsen's Avatar
 
Join Date: Jan 2008
Location: Hakadal, Norway
Posts: 640
Default Re: Kellogg wall phones - need help

The induction coil is an Anti sidetone coil, those were introduced pretty late on LB (local battery) telephones, but it is a wood telephone, and it has cotton cowered cords so this makes me guessing around WWii. Here in Norway those coils where introduced as late as 1934. (The same year wooden telephones became history) Cotton cords remained in use up to 1953. Even when USA was early on telephone development, the kept on making wooden telephones longer, so my guess is approx WWii. Your phone are not mentioned in the book mentioned, still it is a good book!

dsk

PS
Russell W. B. has a good point about how to do it, but this was not common by North Americans, nor Ericsson. The German phones used it: The WWii field telephone FF-33 used the same circuit, with a test button. Norwegian phones used it but had still a hook-switch. (schematics earlier in this thread) By my opinion The German FF-33 is the best (most reliable)hand-cranked field telephone ever made, closely followed by the US EE-8.
DS
Attached Thumbnails
Click image for larger version

Name:	ff33.jpg
Views:	131
Size:	41.1 KB
ID:	157350   Click image for larger version

Name:	BA3115.jpg
Views:	95
Size:	40.5 KB
ID:	157351  

Last edited by dagskarlsen; 14th Feb 2018 at 11:52 am. Reason: Adding a PS
dagskarlsen is offline