[sdiy] OT: Need pf measurement on cap

[cheater cheater]

On Fri, Oct 19, 2012 at 10:20 AM, Tom Wiltshire <tom at electricdruid.net> wrote:
> I'd make up some sort of oscillator circuit (555 or 4047 or something) where I could get a known frequency for a known cap value (say 22pF or 100pf). Then put the mystery cap in and compare. That'd get you into the ballpark, at least.
>
> T.

That's how capacitance meters work, too.

I'd suggest try using a wein bridge.

If the resulting signal is too fast for you, then you can try mixing
and then counting on the sidebands.

Cheers,
D.

>
> On 18 Oct 2012, at 23:56, luther rochester wrote:
>
>> I have a small cap out of an old Polaroid camera that's in the picofarad range. I'm trying to change the exposure time on this bugger.
>>
>> The cap is unmarked other than a small red dot. My Fluke meter doesn't go down that far; is there somebody who could measure this for me? I live in Chicago but I could easily drop it in the mail (I wouldn't need it back).
>>
>> thanks,
>> --
>> ./luther
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