Found in a 1949 Radio Electronics, this 4-tube circuit was fed directly from the mains with a half-wave rectifier.
This circuit is intended for calls to the deaf and is indicated in an old English documentation. LEDs can be...
Suggested by Mullard in a1969 documentation, this circuit generates the erasure signal for tape...
The main feature of this RF oscillator that operates in the range of 100 to 800 kHz is its low...