[Boatanchors] Q of electrolytic capacitors

[Yong Surk Lee]

Thanks for your reply. What I want to know is how to test old electrolytic
caps to see if they leak or not. I thought a leaking cap is equivalent to a
resistor connected in parallel with the cap. How do I find out if an old cap
is leaking or not? Also how much it is leaking.
What I used is an Extech LCR meter. Leaky caps show low Q like 0.5- 2.0 and
higher cap value than its original cap value.
Is there any better way?

----- Original Message ----- 
From: "Brian Clarke" <brianclarke01 at optusnet.com.au>
To: "Yong Surk Lee" <yonglee at yonsei.ac.kr>
Cc: <Boatanchors at mailman.qth.net>
Sent: Monday, November 29, 2004 6:34 PM
Subject: Re: [Boatanchors] Q of electrolytic capacitors


Q is not an important measure of the quality of a capacitor. Firstly, Q
depends on the
frequency at which it is measured - which often is quite different from the
frequency at
which it is used; and secondly, Q depends heavily on how you measure it.

If you really want a good measure of the quality of electrolytic capacitors
that are to
be used in power supplies or as bypass capacitors, measure the equivalent
series
resistance [esr]. This requires a special piece of test equipment. A kit for
this
featured in at least one of the electronics mags a few years ago.

73 de Brian, VK2GCE.

You asked:

My questions is what is the appropriate value of Q for a good electrolytic
capacitor?
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