Telephone sets in the changing times - Germany / German Democratic Republic 1989 - 20 Pfennig

Telephone sets in the changing times With the depictions of telephone sets over the ages, the Ministry of Posts and Telecommunications of the German Democratic Republic is issuing four multicolored special postage stamps, one after the other, in unison. Special cancellations from February 7 to April 6, 1989 Telephone sets through the ages This series of stamps introduces telephone sets from the first half century of their development. In addition to the phone of Philipp Reis (1834-1874), which did not come to practical use, three of the German Reichspost used local battery devices (power supply by batteries at the subscriber) are shown. The 20 Pfennig value shows a Wandapparat of Siemens & Halske from the year 1882, whose housing from polished walnut wood the form of a Wandschränkchens possessed with side-opening doors. The lines were connected to the brass terminals on top. The alarm was mounted below the housing and the incoming call was signaled. The voice and auditory organs of this telephone set were identical. The disguised, horseshoe-shaped electromagnets with an iron membrane, d. H. Siemens telephone system Bell, were only for better handling because of fixed horizontally installed or suspended as a handset on the hook switch. This hook switch switched off the alarm with the receiver off the line and the speech device. With the button on the front the other participant could be called. A fundamental improvement in the performance of telephone sets was possible with the invention of the microphone by David Edward Hughes (1831-1900) in 1878, which came in various forms at the Deutsche Reichspost from 1887 used. The telephone sets presented on this stamp series as well as other, from these and later stages of development can be visited in the Postal Museum of the GDR.