Consider the simple Zener regulator circuit from Wikipedia:
Zener diode - Wikipedia, the free encyclopedia
I understand the resistor is required to keep excess current from destroying the Zener. However, assume this circuit is powered by a 9v (PP3) battery, and the output load is two 20mA/3.6v LEDs in series which will never be disconnected (so no open circuit protection is required). We're using a Zener of approximately 7v to avoid damage to the LEDs.
Can the resistor be omitted in this scenario, to improve the length of time the LEDs will light as the battery is depleted? I don't think there will be any efficiency gain (as the Zener will still be dissipating as heat whatever current the resistor would have dissipated), but: without the resistor to drop the voltage to the LEDs, I'm thinking they will light longer after the battery drops below the Zener voltage and the Zener falls out of the circuit.
Thoughts?
Zener diode - Wikipedia, the free encyclopedia
I understand the resistor is required to keep excess current from destroying the Zener. However, assume this circuit is powered by a 9v (PP3) battery, and the output load is two 20mA/3.6v LEDs in series which will never be disconnected (so no open circuit protection is required). We're using a Zener of approximately 7v to avoid damage to the LEDs.
Can the resistor be omitted in this scenario, to improve the length of time the LEDs will light as the battery is depleted? I don't think there will be any efficiency gain (as the Zener will still be dissipating as heat whatever current the resistor would have dissipated), but: without the resistor to drop the voltage to the LEDs, I'm thinking they will light longer after the battery drops below the Zener voltage and the Zener falls out of the circuit.
Thoughts?