This circuit was found in a 73 amateur radio magazine from the 90s. An LED extends the scale from 0 to 5 V to 10 to 15 V in this bargraph circuit. Other zener values can be used.
Using the CA3140 in the figure we have a comparator that goes low in the window voltage space. The...
This circuit is found in a 2011 technical publication from Texas Instruments. It is an amplifier for...
In this circuit, the LED lights up when the current is such that multiplied by the resistor value...