P. G. Wilson wrote:

> Is it true that rectifiers generate a constant minimum AC voltage (rms)
> that causes variable ripple depending on actual or overall voltage?  In
> explanation, is ripple defined by the minimum AC voltage over the rated
> output voltage only?

> Could the group enlighten me on the subject of minimizing ripple and how
> it affects plating?  There's been much discussion about copper plating,
> and I would appreciate some information on this topic.
> Chemist, IUP, CU
> P.G. Wilson
> [log in to unmask]

I am reluctantly answering this post since I have no 
plating experience. 

Several things have been stated in this question that 
I think need clearification.  Yes, rectifiers that 
transform AC to DC have ripple.  In a power supply, 
commonly called an unregulated power supply, the ripple 
is determined by the filter cap and any load resistance 
as seen from the DC output of the power supply. 

A simple unregulated power supply could be just a transformer, 
full bridge rectifier, output filter cap, and the resistive 
load.  In this setup, the ripple is ONLY determined by 
the combination of the load and the cap.

Now I don't know how technical you want to get, 
but here's something to think on: 

Let's call the min/max value of just the output 
ripple the peak-to-peak ripple = Vripplw(p/p).  
This is NOT measured with hand held meter.  This 
is measured with an oscilliscope.  It assumes the 
min value is zero volts - the datum if you will.  
The max value is measured up from the min by 
however many volts it is.  It is a "RELATIVE" 
measurement to start getting technical.  

Now, let's do an "ABSOLUTE" measurement on the output. 
We want to measure the peak output voltage from REAL 
zero volts also with an O-scope.  We will call this 
measurement = Vpeak.  We'll also call the output 
cap = Cout, and the output resistor (load) = Rout. 
We also have to know the frequency of rectification, 
i.e. fulwave is 120 Hz, half wave is 60Hz, etc... 
We'll call this f. 

Theoretically,   Vripple(p/p) = Vpeak/[R*C*f]

For full wave rectification (120 Hz), 

Vripple120(p/p) = Vpeak/[R*C*f]

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The comments and opinions stated herein are mine alone,
and do not reflect those of my employer.
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