This car battery monitor was featured in the January 1988 issue of Radio Electronics magazine. The circuit uses common transistors and has 3 levels of indication made with common LEDs.
Found in Radio Electronics this circuit uses a fotodiac to drive a triac. The circuit can use...
This circuit was found in an Electronics Now from the 90s. The frequency depends on the crystal. The...
This power supply for gas laser was obtained in an American documentation from the 90's. The...