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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