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 is a commercial circuit from the year 1958. Transistors are germanium types and transformers...
This circuit was found in American documentation from the 1960s. The operational amplifier is from that...
This circuit can be used in alarms, data links or áudio links using IR radiation. The circuit is...