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.
This circuit has both frequency and duty cycle control. We found it in the October 1992 Radio...
This power supply is indicated for the supply of not very powerful car radios of the AM and FM...
In the absence of a modulation signal, the carrier of this simple short-range transmitter is cut...