Found in a 1960s documentation, this circuit uses an operational amplifier from the time and a current diode, both of which are difficult to find today.
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...