The sensor is S1 in this alarm that we found in a Radio Electronics magazine from May 1971. Several sensors can be used in series. The SCR supports equivalents from the 106 series.
This sequential circuit of LEDs was found in a Popular Electronics from the 90s. The circuit can be...
Indicated for 12 V systems, this circuit was obtained in a 90s Siliconix documentation. The...
This circuit for light modulated in frequency (FM) operating at 50 kHz was found in a 90’s...