Decoding Pulse Telephone

[keithdoxey]

Thats interesting. I see two pair of wires coming out of the dial. So one pair is sure the digit pulser, the other might be exactly that, the home position. Maybe they used that to mute the earpiece?

Sure I can make good use to it.

Ioannis

The dials in British phones had 5 contacts. 2 of them were the pulsing contacts which were normally closed and pulsed open for the dial pulses. The other three contacts were normally open and are referred to as the "Dial Off Normal" contacts. They placed a short across the earpiece to prevent acoustic shock and also a short across the carbon granule microphone to prevent the back EMF surges from welding the granules together.

http://www.britishtelephones.com/howdial.htm

Keith