Hearing aid amplifier (T1580E)

This circuit is from a 1947 Radio Electronics. The 4-tube circuit is battery powered and uses a crystal phone.

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Electronic Slot Machine (CB6893E)
This digital electronic game circuit was found in a 1982 publication. It randomly draws the...
Logic Level Controlled Alarm (CB19899E)
This circuit can function as an output shield for microcontrollers, being compatible with TTL...
Current Amplifier (CB13747E)
We found this circuit in the 1977 RCA Solid State ICs. The circuit consists of a current amplifier with...