Voltage regulator for 9v to 3.6V,  Zener and NPN transitor.   Ref: Book: Analog and Digital Electronics .2nd Edition by Peter H. Beards.  

Breadboard and schematic of for a simple Voltage regulator for 9v to 3.6V. 

 

Just 4 components needed.

 

If you have a 3V Zener try a 102 ohm resistor for base-collector.

Has Schematic and Breadboard layouts . ideal for experimentation.

 

Ref: Book: Analog and Digital Electronics .2nd Edition by Peter H. Beards.