Found in documentation from the 1980s, this circuit uses an operational amplifier from that time. Transistors are also from the era, and general-purpose equivalents can now 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...