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.
This circuit is from a 1960 book by Hugo Gernsback. The transistors are germanium from the time....
This ultra-low power circuit makes the LED flash. The circuit is powered by 15 V in this...
This source was found in European documentation from the 1980s. The C5 input capacitor must be...