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Re: capacitance of homemade caps

Original poster: Terry Fritz <teslalist@xxxxxxxxxxxxxxxxxxxxxxx>

Hi Steve,

One "can" measure capacitance and inductance with just a scope. But it is not at all simple. You pulse it and watch to see how fast it discharges across a resistor. I don't think it is worth trying unless you have someone there that knows the technique well... Best to look around for someone that has a meter that just "tells" you such things... Needs a signal generator and some good knowledge of impedances... It is just too messy for a first time scope user...

You have mentioned 833Hz which seems way way too low... Maybe like 83300Hz... MMCs are real easy since it is just printed on the side of the cap ;-))) Might double check the time and voltage scales on the scope...

Don't ground your coil to the AC wall plug!! That ground is great for 60Hz stuff, but terrible at say 83kHz!!! you might fry everything on the circuit. Ground the coil to a little ground rod which is like 1000X better!! cold water pipe or copper drain pipes are great too. Higher frequencies just don't like to travel in the normal household grounding that was never made for such high frequencies.

There are some folks that "flush" some bare wire down the toilet to get to the sewer pipes which are very well grounded... Sort of "extreme", but "electrically" sound ;-)) Might not be good at the top floor of a tall building ;-))



At 06:13 PM 4/6/2005, you wrote:
Thanks. I am indeed already getting some MMCs, I just think it would be cool to have it running off the strorag boxes. :) Seen on this website:
Also, I've got an o-scope with abuilt in signal generator at my school, but I cant get it to do anything with the box caps. I maintain, perhaps stupidly, that my caps have a minimum voltage requirement and the function generator simply can't reach that. I could be wrong, but I don't think so. :)
Steven Steele