This timer with two unijunction transistors and one SCR was found in an American documentation from 1964. The unijunction transistors could be the 2N2646.
This circuit was found in a 1980s Intersil documentation. The integrated circuit used is not...
Although it is a common configuration today, these circuits were taken from an old publication. The...
This circuit, from an old publication, can also use modern transistors. Note that the unit is...