Found in an Electronic Design and 1970s, this circuit uses transistors of the time. The transistors can be replaced with equivalents and the relay is 12 V depending on the power supply.
The oscillator shown generates a rectangular output signal at a frequency of 5 MHz, determined by the...
Found in a Popular Electronics - January/February 1969 this circuit was intended to increase the...
Found in a radio amateur magazine of the 1980s, this circuit uses components that can still be...