We found this circuit in a 1986 documentation. It uses only LEDs, batteries, resistors and the power supply which can consist of 4 batteries or a 9V battery. The basic circuit uses two-color LEDs.
Found in a 1991 Hobbyst Handbook, this circuit monitors both battery and alternator voltage. The set...
Found in RCA documentation from the 1970s, this circuit uses currently unusual integrated...
Among the alternative energy sources, one of the most promising is that represented by Astro-Rei....