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Old 26th July 2010, 05:05 PM   #401
Russellc is offline Russellc  United States
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Quote:
Originally Posted by jacco vermeulen View Post
Scuse me.
"in situ" is fancypants latin for "at location", you measure the cap while it's mounted on the board, 5pF is uncanny little.

The 5pF and the 1M resistor make a high pass filter, ~31.847 Hz with f = 1/(2*Pi*R*C) , dampens everything below that by 10dB per decade.
Means, if you feed the cap a signal from a sinus generator that's 1/10th of that frequency, you'd see an amplitude on the output that's 10dB smaller if the cap is 5pF.
If you use two known caps of different value, you can precisely figure out the stray capacitance of the board.

(stuff i had poly-u classes in, both math classes and audio amp electronics, so please don't see me as some wise-guy jinni)
Thank-you for describing the technique in detail. I knew what you meant be "in situ" I just wasnt following on the "how to" of it. I'll have to wait until I have a little more equipment to pull that off. All in good time.

Thanks again,

Russellc
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Old 26th July 2010, 05:13 PM   #402
Zen Mod is offline Zen Mod  Serbia
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F=1/(2xPixRxC)=1/(2xPix1000000x0,000000000005)=31830=31K830Hz
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Old 26th July 2010, 05:59 PM   #403
jacco vermeulen is offline jacco vermeulen  Netherlands
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Quote:
Originally Posted by studeb View Post
What is missing?
Sorry about that, i just ran an estimate by head.

pF times a Million is 1/Million, so 1 divided by (5pF *1M) is 1/5th times a Million, is 200,000
200,000 divided by 2*3 is 33,333
3 is 4-2/3 % off for a rounded off pi of 3.14
Makes 31.847Hz, so the real corner frequency is ~31.847Hz or ~31,847 for the US.
(i'm a turd)

Last edited by jacco vermeulen; 26th July 2010 at 06:07 PM.
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Old 26th July 2010, 08:20 PM   #404
Nelson Pass is offline Nelson Pass  United States
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Quote:
Originally Posted by wayne View Post
Are we sending out 8 FETS or 12 with the boards?
I just got back from the coast, and I checked to confirm that
concurrent with the new price it will be 6 matched parts per board.

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Old 26th July 2010, 09:23 PM   #405
godfrey is offline godfrey  South Africa
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Quote:
Originally Posted by jacco vermeulen View Post
200,000 divided by 2*3 is 33,333
i.e. about 30 kHz, not 30 Hz
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Old 27th July 2010, 04:04 AM   #406
ichiban is offline ichiban  United States
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Quote:
Originally Posted by Nelson Pass View Post
I just got back from the coast, and I checked to confirm that
concurrent with the new price it will be 6 matched parts per board.



Is there an option for the early purchasers, that were sent 4 per board, to get the needed 2 more matched sets.
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Old 27th July 2010, 08:48 PM   #407
Russellc is offline Russellc  United States
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Quote:
Originally Posted by ichiban View Post


Is there an option for the early purchasers, that were sent 4 per board, to get the needed 2 more matched sets.
Same here, glad to pay up for the matched pieces needed!

Russellc
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Old 28th July 2010, 01:48 AM   #408
Benedetto is offline Benedetto  Germany
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Old 28th July 2010, 02:44 AM   #409
ichiban is offline ichiban  United States
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Quote:
Originally Posted by Russellc View Post
Same here, glad to pay up for the matched pieces needed!
Russellc
Yes, I wasn't looking for freebees, but would like to purchase the matched pairs we would need.
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Old 28th July 2010, 02:16 PM   #410
Russellc is offline Russellc  United States
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Originally Posted by ichiban View Post
Yes, I wasn't looking for freebees, but would like to purchase the matched pairs we would need.
exactly. The deal was what it was, I would have to purchase them anyway.
I just dont want to have to buy a bunch of them, learn to match them, obtain what I need and match them, if I can just purchase them. Hardly a reason to declare a "perfect world" unless someones's world is WAY messed up. Its only a component. I've had the ZEN aand Bride of Zen for over 10 years with out building them, I'm sure this can wait without anyone's world not being perfect.

Otherwise, how are these dudes matched? If its doable for me, I'll match a load of them. Now, everythings perfect again!

I'll call and see what the dealio is at Pass Labs.

Russellc

Last edited by Russellc; 28th July 2010 at 02:19 PM.
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