This circuit is from American documentation from 1970. It can be designed with a BC558 and for the operational, we can use equivalents. The FET can be the BF245.
This circuit was found in old documentation. The SCR can be any of the 106 family. Note the sensor...
This circuit was found in Ferranti's 1974 transistor manual. The transistors are from the period and...
Short duration pulses can be obtained with the relaxation oscillator that uses common transistors and is...