I'm trying to design a battery powered constant current regulator for a LED with a forward voltage of 2.1V and a nominal current of 30 mA.
I've seen simple current regulators based on a JFET and resistor here and here. I'd like to modify this circuit to minimize the additional voltage overhead above the 2.1V for the LED's forward voltage and to shut off/remove the load when the batteries have discharged low enough that they cannot supply the 2.1V + overhead voltage for the current regulator to maintain it's current.
Thank you!
I've seen simple current regulators based on a JFET and resistor here and here. I'd like to modify this circuit to minimize the additional voltage overhead above the 2.1V for the LED's forward voltage and to shut off/remove the load when the batteries have discharged low enough that they cannot supply the 2.1V + overhead voltage for the current regulator to maintain it's current.
Thank you!