Zener regulated power supply circuit lab

DFO6M integrated cct bridge rectifier
1N4742 zener diode (12v)
25 vrms c.t. transformer
1 - 220uF/50V min. capacitor
2 - 1.2k resistors in parallel in the circuit
1 - 1k ohm resistor for load

i do not remember how to calculate the zener current. Can anyone help?
Also, how can i draw ccts on the computer with all the icons and values in it so i can use these boards better?

Thank you for your time either way!!

Thomas
1st year electrical engineering student

 

The important specs here are the zener wattage, which is very analogous to resistor wattage, it sets up the maximum current through the zener diode. Real world design you have to figure out if the load will ever be removed, since the zener will have to absorb the excess current.

Zener current is Ohm's Law, with the zener being a fixed voltage in the equation. You use the remaining voltage across the resistor to calculate the current through the fixed resistor.

http://www.allaboutcircuits.com/vol_3/chpt_3/11.html