This circuit is from a 1968 documentation using one of the first integrated circuits available at the time, the TAA370. The circuit is powered by 1.3 V using a 200 ohm handset.
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...