Voltage Sense using an LM393.
The mosfets aren't needed in real world applications — they're acting as the collectors of the LM393 outputs.
(Can be used with a diy op amp comparator by using the mosfets as simulated or by using the outputs to power the LEDs directly.)
Red LED = battery < ~3.3V.
Green LED = battery > ~3.3V
Using 5ma LEDs here.
Use a potentiometer/trimmer for your two voltage divider reference.
