Found in a 1990s US publication, this alarm circuit detects when a light beam is interrupted. Optical resources may be used for the sensor and instead of the alarm a relay may be used.
November 2016 - NXP ARM Cortex microcontrollers for serial interfacing applications, NXP 32-bit...
Transistor Q1 can be a BC558 and Q2 a BC548. This circuit detects when a pulse is missing from a...
This traditional complementary symmetry circuit provides 20 W of rms power at a load of 8 ohms...