Found in the June 1987 issue of Radio Electronics magazine, this circuit uses well-known CMOS components. The circuit has a CMOS amplifier stage that drives a small speaker.
This circuit locks when the sensors are opened. The relay can be 6 or 12 V depending on the power...
The circuit shown is from Texas Instruments optoelectronics documentation. The input signal is...
Using the CK722 this directional photometer was published in Radio Electronics magazine in July...