# Electronics help! recitifier with a zener diode

1. Mar 15, 2011

1. The problem statement, all variables and given/known data
Design a rectifier with a zener diode that satisfies the following:
Primary voltage = 120V @ 60Hz
VDC = 12V
IR2 = 100 mA (R2 being the load)
Vr(R2) <= .3V

2. Relevant equations
C=IDC/(2fVr)
IDC=IR3 + IR1

3. The attempt at a solution
I tried calculating the capacitor, but how am I supposed to get IDC if I dont have any other current?

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2. Mar 15, 2011

### MATLABdude

Remember that a reversed Zener diode clamps the voltage, but must be above the zener current ($i_{zk}$) in order to do so:
http://www.electronics-tutorials.ws/diode/diode_7.html