# Recifier circuits, filter conducted to regulator !

Discussion in 'Homework Help' started by Mas767, Mar 20, 2011.

Mar 20, 2011
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2. ### Audioguru New Member

Dec 20, 2007
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Your links don't work or are too far away to work or the server for them is asleep. So please post your schematics here instead of way over there.

3. ### Mas767 Thread Starter New Member

Mar 20, 2011
2
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i don't know what the problem is , but i uploaded them in the attachment now

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4. ### t_n_k AAC Fanatic!

Mar 6, 2009
5,448
783
If one assumes the 1V ripple is the filter capacitor voltage ripple then .........

The capacitor voltage would have a peak of 15-0.7=14.3V and a minimum of 13.3V [since ΔVcap=1]

The mean capacitor voltage would be ~(14.3+13.3)/2=13.8V

A mean zener current of 20mA [for nominal 10V zener voltage] would require a total series resistance

R+rz=(13.8-9.8)/20mA=200Ω

Hence R=190Ω [since rz=10]

Required capacitance....

The discharge time=asin(13.3/14.3)/ω+T/4=3.17ms+4.17ms=7.34ms

Hence C=I*Δt/ΔVcap=20e-3*7.34e-3/1=146.8uF

I have the unloaded zener ripple voltage as 50mV.

Last edited: Mar 21, 2011
5. ### t_n_k AAC Fanatic!

Mar 6, 2009
5,448
783
With the 22uF instead of 146.8uF the load ripple is obviously going to be larger. The problem in this case is that the linear capacitor discharge assumption breaks down and one must solve for the ripple in an iterative manner or by direct simulation.