Found in old documentation, this circuit can be implemented even today with the use of a 2N2646 for the unijunction and a TIC106 for the SCR.
This circuit was found in a 90s Popular Electronics. It is used for the acoustic transmitters of 40 kHz,...
Common general purpose silicon diodes when direct biased provide a voltage fall of about 0.6 to...
Found in General Electric's 1969 documentation, this circuit uses two Foto Darlingtons to control...