TM 11-2541: Speak-O-Phone Sound Detector, Model SDB

TM 11-2541 Speak-O-Phone Sound Detector, Model SDB

TM 11-2541

Speak-O-Phone Sound Detector, Model SDB

Army · TM · Jan 1944 · 26 pages

About

RESTRICTED SECTION DESCRIPTION 1. PURPOSE. The Speak-O-Phone Sound Detector, Model SDB, enables the operator to listen to conversations without the knowledge of those speaking. The equipment is adapted for use under four different conditions, as follows: a. When it is possible to "plant" a microphone in the room prior to the conversation taking place. b. Where it is not possible to gain access to the room where conversations are taking place, but where a wall or panel of an adjoining room is available. c. When it is desired to "listen in" on telephone conversations by a direct telephone-line tap. d. When it is desired to "listen in" on a telephone-line by use of induction coil tapping, without actual wire connection. Google

DesignationTM 11-2541

EditionJan 1944

StatusSuperseded

Pages26

FunctionComms Signal

CollectionHistoric

Public domain (U.S. Government work)