Telos Krakow Poland APK sound powered telephone

Telos Krakow, APK secondary set, sound powered telephone

wall hung / mounted

cast metal with lots of patina

There is this odd thing: a sound powered telephone. It needs no power, just a direct connection to another sound powered phone, or a small network of sound powered phones. 

“Sound powered telephones, handsets or headsets, contain electro-mechanical transducers that convert voice directly into electrical energy. This signal is sent down to a two-wire line and converted back into voice at the other end. The phones require no batteries, amplifiers or power supplies, emit no electro-magnetic or radio-frequency interference, present the user with no shock hazard and yet are capable of transmitting clear voice communications over distances up to five miles.” (tekst by Dynalec)  

These were (and still are) used in situations where power failures were common and it was imperative that people still be able to communicate. Factory’s, tunnels, coal mines and on boats. Also, after installation there were no further costs, these are very low maintenance and long lasting. 

What looks like it might be a hand-crank for a small generator is an on-off switch (there are no circulair scratches from people cranking away over the last 50 years). The rotating knob is for selecting which location you wanted to call.

industrial, vintage, retro, phone
ship, maritime, decorative, object, decor
old, rugged, rough, tough, work environment

phone is 14 cm deep, with handset 20 cm