Signals of up to a few tens of kilohertz can be generated by this circuit found in a European publication from the 1980s. Transistors admit equivalents and the unijunction can be 2N2646.
I found this circuit in a documentation about thyristors from the 70s. The circuit uses a diac...
This circuit triggers by choosing the higher of two voltages. The circuit is from a 1964...
The integrated circuit used in this 80's mixer is the LM301A. However the circuit can be used to...