Amplifiers used to detect approaching aircraft, Bolling Field
"This auction includes an M4 Enigma machine with an estimated price of $280,000 to $350,000 and while that's not particularly affordable, only 120 of this four-rotor model M4 Enigma machine are believed to have survived. These are mainly in official hands making this a particularly rare opportunity for collectors to acquire one of the iconic machines of the Second World War in perfect working order."
Dutch personal horns: One of the experimental 'personal sound locators' tested by the Dutch military research station at Waalsdorp, before the personal parabolas above were adopted as the best solution.
1925 The Isolator is a bizarre helmet invented in 1925 that encourages focus and concentration by rendering the wearer deaf, piping them full of oxygen, and limiting their vision to a tiny horizontal slit. The Isolator was invented by Hugo Gernsback,.
1946 The ENIAC was invented by J. Presper Eckert and John Mauchly at the University of Pennsylvania. ENIAC stands for Electronic Numerical Integrator and Computer. By the time ENIAC was completed in November of 1945 however the war was over.