(https://upload.wikimedia.org/wikipedia/commons/thumb/2/21/Joule_thief_schematic_const_voltage_de.svg/1218px-Joule_thief_schematic_const_voltage_de.svg.png)

Without the Zener diode, Voltage is 20volts+ but with the zener, voltage is 6v(I am using 6v2 zener). My problem here is : Why is the zener diode VERY HOT TO TOUCH?

These are the parts I am using;

3.7v dc LI-ION battery

Toroidal inductor(10 turns on primary and secondary, inductance would be 10uh each)

D882 transistor

570 ohms resistor

SR260 Fast switching diode

100uf 25v capacitor.

Any help would be greatly appreciated. Thanks.

(I feel like adding cooling paste on the Zener).