Alt-BEAM Archive
Message #01749
To: Jacob Booth J.Booth@mackillop.acu.edu.au
From: "Paul B. Webster VK2BZC" pwebster@clinipath.com.au
Date: Thu, 25 Mar 1999 18:09:46 +1000
Subject: [alt-beam] Re: Ripple current and Goop problem
Hello Jacob.
> 1. what is the term 'ripple current' meaning in relation to
> capacitors? I have a catalog here and one of the specs for these caps
> is there 'ripple current'. Any ideas?
In the power supply application described by another reader, the
capacitor is charged only toward the middle of each half cycle. For the
remainder of the half cycle and until the point in the next half cycle
when the rectified voltage exceeds that remaining on the capacitor, no
current is flowing in the transformer secondary and the capacitor is
supplying the load current.
This means that the majority of current supplied to the load comes
*from* the capacitor, and this amount of charge is *returned to* the
capacitor during the short peak of each half-cycle. The capacitor thus
gives out and receives again during the cycle, most of the load current
so the "ripple" current flowing into it is quite comparable to the load
current. For a 2 Amp supply, the capacitor must be able to handle at
least 3 Amps AC ripple.
> The problem is, it has been fixed inside with some kind of herculean
> double sided tape. What should I do to get it off?
Eucalyptus oil.
> PS I noticed that there is a tiny LED inside what looks like a
> standard glass diode 'shell'. Was this used to load the cell when not
> in use, or as a zener style voltage regulator? Can I buy these type of
> LED? I have looked in all the catalogs I have, and to no success.
You mean it actually glows? The closest would be a SMD type LED which
are usually in a plastic encapsulation. Try Vorlac.
If it doesn't glow and is in series with the solar cell, it is
probably a Schottky rectifier to prevent the solar cell discharging the
reservoir capacitor during momentary shading of the cell.
--
Cheers,
Paul B.
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