Re: super cheap capacitance/inductance Tesla coil metering

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Chris Rutherford <chris1@xxxxxxxxxxxxxxxxxxx>

I once made a capacitance meter with some comparators, and
some decimal counter logic.  Cap V=0 Timer starts, Cap =V*66%
(comparator set to detect this) Timer stops.  Based on RC time constant.
Change R by order of magnitude to set scale.  Time directly proportional
to capacitance.


Thanks

Chris

On Tue, 2005-11-29 at 19:55 -0700, Tesla list wrote:
> Original poster: "Jon Danniken" <danniken@xxxxxxxxxxx>
>
>  > Original poster: Terry Fritz <vardin@xxxxxxxxxxxxxxxxxxxxxxx>
>  >
>  > Hi All,
>  >
>  > Making an oscillator with a 555 timer to measure capacitance is on my
>  > mind.  I "think" it could do inductance easily too...
>  >
>  > I was thinking of a trivial LM555C timer circuit powered by a 9V
>  > battery that would plug into the sound card jack of a computer to
>  > read the frequency.  A little program might be able to do the math
> directly...
>  >
>  > Thus, one might be able to make a LC meter for like $5 which I think
>  > many of us would like.
>  >
>  > There is probably some free program out there that does the "sound
>  > card input jack to frequency readout" function????
>  >
>  > Everyone has a sound card these days and plenty of resistors protect
>  > the computer...  So the "high level" hardware is already done...
>  >
>  > I suppose such a thing could be made into a Tesla coil primary and
>  > secondary "tuner too"...  A PC with a sound card plus some cheap and
>  > easy "Radio Shack" parts is a pretty powerful machine!!! It really
>  > could be a sound out cable to alligator clips and a resistor
>  > protected similar input cable if you had nice software...
>  >
>  > I know the hardware side, but not the software side...
>  >
>  > Hmmmm....
>  >
>  > It would be a cool addition to Tesla coil design programs...  I would
>  > love to be able to send out $10 worth of stuff for someone to hook to
>  > their coil and it would read back everything we need to know about it
> ;-)))
>  >
>  > Just a thought...
>
> That sounds like a fantastic idea, Terry.  If you can "squeeze" the
> frequencies into the ~20kHz bandwidth of an average soundcard, this would be
> a tremendously useful device for those of use without regular scopes.
>
> On the software side, the main freeware PC Oscilloscope I have found is the
> one at MSU on this page:
> http://polly.phys.msu.su/~zeld/oscill.html
>
> Jon
>