Found in a 1967 Electronics World, this oscillator changes its tone when objects move in their environment. The output is made on a low impedance phone.
This circuit was found in a 1977 documentation. It limits the voltage from a source using zener...
This simple radio uses few components due the direct coupling of the transistors. Coil is formed...
In the figure we have the way to implement an Exclusive OR or XOR gate with CMOS or TTL...