This circuit is from an American 1967 documentation and can be implemented with modern equivalent transistors. The circuit serves as a Q multiplier.
The duty cycle of a Schmitt Oscillator can be programmed by R1 and R2 in this circuit. The...
This circuit is from a Popular Electronics from 1992. It uses two SCRs and can be triggered by...
This simple SCR alarm circuit was found in an old Poptronics, but can be easily assembled as all...