This circuit was found in an English publication from 1967. The circuit is for listening on a phone. Transistors are types of germanium of the time.
This shield circuit was found in an American publication from the 80's. The triac is of low...
The Variable Frequency Oscillator (VFO) shown in the figure can generate signals in a frequency range...
This circuit was obtained from an 80's Radio Electronics. The circuit decodes “scrambled” or...