With this circuit it is possible to obtain a higher voltage from a zener diode. The circuit is from a 1970’s EEE. The device used as a constant current source is uncommon today.
We found this VU circuit with special effects in an LED array in a 1991 documentation. The circuit...
This game with digital logic circuits was found in the December 1976 issue of Radio Electronics magazine....
This 2009 circuit is a bilateral call warning. Easy to build, using light communication between two...