This circuit uses a capacitor that depends on the frequency of the crystal. We found it in a 1967 documentation. The maximum frequency is around 100 kHz.
This 1.2 to 32 V x 3 A regulator was found in an 80's EDN. The power components must be equipped...
When a pulse of light reaches the sensor [a CDs cell or LDR] the flip-flop changes its state....
This sophisticated photometer that has a light comparator with LED indicator came out in an...