What will do if you want a low voltage less than 3 volts as reference voltage for a circuit? Usually we use a low volt Zener to give low voltage to a particular section of the circuit. But Zener below 3.1 V is not available. So do this simple method. The LED can act a Zener to give a reference voltage. Each type of LED has a forward voltage drop that range between 1.7 V to 3.3 V. This forward voltage drop slightly increases when the input voltage increases. This is due to the increase in the luminosity of the LED. So let us exploit the LED to do the job of the Zener.
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