This simple circuit has good gain and can be implemented with any general-purpose transistor. The circuit is from Electronics Now, June 1997. The coil determines the frequency range.
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...