This harmonic oscillator controlled by crystal was found in an American documentation of the 90's. The circuit uses transistors of the time. Current equivalents can be used.
This circuit serves as a reference to learn how signals were decoded in the 1960s. The fully...
The 4047 is a monostable/astable CMOS multivibrator. The basic con- figuration is triggered by the...
This simple metal finder uses a 100 uA indicator. The exploration coil must be constructed in a...