The WWII was the scenario of the biggest developments in Electronics to warlike end. The engineers developed accurate types of navigation systems, new methods for detecting enemies' submarines like the SONAR, as well as sophisticated electronic intelligence procedures by using complex cryptographic code systems and electronic countermeasures devices.

(a) Radioreceiver model BC-348 manufactured for the American Armed Forces in several versions.
(b) Portable transceiver model BC-611-J, manufactured in U.S.A., by the Galvin Mfg. Co.
(c) Air transportable sea rescue transmitter model SCR-578 known in the American military jargon as Gibson girl.
(d) Radio receiver made for the Japanese Armed Forces.
Collection Edison de Freitas.
(e) Microphone model nº 7 used in communication systems of combat cars of the US army.
Illustration of the manual of instructions, AN-09-10-209 showing the main parts of the receiving radio model BC 348.

Lleft, campaign telephone model EE-8-B and, to the right, a more modern model, TA 43/PT, manufactured respectively for the Kellog Corporation and W.Electric, U.S.A.
Iillustration of the manual of instructions, AN-08-10-209 showing the power supply system, called of Dynamotor, used for the receiving radio model BC-348.

To the right, radio-receiver model SLR-M, also manufactured in version SLR-F. Destined to coastal installation or ships stations. He was known as moral receiver, or either a receiver destined to the entertainment of troops in conflict areas. When installed in ships it had its circuits provided with special shield to block the radio-frequency emitted for the oscillator that could be detected by radiogoniometry equipment installed in enemy submarines and, indicating the ship position. The shield principle or radio-frequency armored circuit was invented by American engineer Marvin Hobbs under patent nº 2.314.309, when working for Scott Laboratories Radio, manufacturer of this receiver.