This circuit, found in 1993 documentation, is the traditional relaxation oscillator configuration with unijunction transistor. The frequency depends on C and the resistance value R.
This circuit appears in similar versions on this site. This is from a Popular Electronics from the 80's. The...
This two-transistor delay circuit from the 1960s was found in documentation from the time....
This circuit operates with signals from 150 kHz to 1 MHz and makes use of a known NAND CMOS gate....