This circuit was obtained from the September 1977 issue of Radio Electronics magazine. The circuit is based entirely on transistors and two SCRs. The power supply with the inclusion of a battery is given.
Frequencies up to just over 100 kHz can be obtained with an oscillator based on one of the four...
This circuit, found in a Popular Electronics from 1992, is based on an oscillator and a crystal...
This is a discrete equivalent version of an open collector TTL gate. What we have is an inverter...