French Thomson-Houston Model 1924

[countryman]

The model PTT 1924 was also discussed in this thread. It's a successor of this earlier Thomson Houston phone and a predecessor of the U43.

Unlike the earlier candlestick, the 1924 has an induction coil for anti-local. But still there is a DC current through the receiver element. The later U43 uses a much more "mainstream" network.
http://www.l2l1.com/tech2.htm#ptt24 and http://alain.levasseur.pagesperso-orange.fr/ also have wiring diagrams, but like the sticker inside the phone these diagrams are not laid out very clear.
I tried to draw a simplified diagram of the PTT 1924 to show the unusual wiring of the network. A1-A2 is the pulse contact of the (optional) dial, CC1-CC2 is the choke contact. Both other contacts are the hookswitch.

[FABphones]

The model PTT 1924 was also discussed in this thread....  ....a predecessor of the U43.

Not intending to go off-topic but I may just add:

The Laurent - 1941 - was made before the later U43.
Thread (includes wiring diagram):
http://www.classicrotaryphones.com/forum/index.php?topic=21136

Internal PTT24 photos (and wiring diagram) on this thread:
http://www.classicrotaryphones.com/forum/index.php?topic=21102

[Jack Ryan]

The predecessor to the Model 1924 - both desk and wall version - were designed by Thomson Houston and were based upon Automatic Electric series circuit telephones. The receiver was electromagnetic (no permanent magnet).

The Model 1924 was designed by LMT (Western Electric) and contained an IC but retained the electromagnetic receiver. I think it was 1934 when the Model 24 handset was updated to use a conventional receiver.

The U43 was designed by Ericsson and used a more conventional (for the French) circuit.

The Laurent was an interesting but fleeting telephone - Bakelite like the U43 but with the Model 1924 handset.

Jack

[countryman]

I found a glue-in diagram in better condition: