We found this circuit in a spy book from the 90s. Transistors admit equivalents and the coil can be designed as in the CB19425E project. Power is provided by cells or 9 V battery.
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...