This simple timer with unijunction transistor was found in an old American technical documentation. We can use 2N2646 for the unijunction and BC548 for the transistor.
Found in EEE documentation, this circuit can have the duration and frequency adjusted separately....
August 2016 - Mouser Electronics is providing the ew converters step down LM53625-Q1 and...
The circuit is from a 1966 English magazine, but it can be assembled with more modern transistors such as...