This 555-based circuit was obtained from the 1995 Encyclopedia of Electronic Circuits volume 5. It triggers an SCR when the transistor is cut off.
Found in Philips documentation from the 1970s, this circuit uses components from the era. The...
Two transistors on a regenerative switch are used to trigger a triac. This circuit is from the RCA...
The opening of the sensor in this circuit of the 70's causes an integrated buzzer of the Sonalert type...