Xref: utzoo sci.electronics:9173 sci.physics:10845 rec.ham-radio:16266
Newsgroups: sci.electronics,sci.physics,rec.ham-radio
Path: utzoo!henry
From: henry@utzoo.uucp (Henry Spencer)
Subject: Re: Capacitance Meter Stuff (Long)
Message-ID: <1989Dec28.234113.12838@utzoo.uucp>
Organization: U of Toronto Zoology
References: <1077@swbatl.UUCP>
Date: Thu, 28 Dec 89 23:41:13 GMT

In article <1077@swbatl.UUCP> adams@swbatl.UUCP (4237) writes:
>Seems that with a 555, some judicious values of f and careful choice of
>value and range of C that an inductance meter is almost trivial if one
>can reasonably accurately measure C. 

Also of relevance:  with a 555 and some resistors, plus a frequency counter
(which is trivial to build), you *have* a capacitance meter.  Just build
an RC oscillator and measure the output frequency.  Mind you, you need a
bit of arithmetic to go from frequency to capacitance, but a $10 calculator
solves that unless you're measuring lots of capacitors and speed is important.
(Our old electronics wizard, now retired, pointed this out to me during a
discussion of cheap test equipment.)  It may not give you five-digit accuracy,
but capacitor values are seldom that crucial (and can seldom be depended on
to be that stable) anyway.
-- 
1972: Saturn V #15 flight-ready|     Henry Spencer at U of Toronto Zoology
1989: birds nesting in engines | uunet!attcan!utzoo!henry henry@zoo.toronto.edu