Bouncy Tach, ...I tried the fix |
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Bouncy Tach, ...I tried the fix |
yeahmag |
Apr 28 2010, 11:04 AM
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#1
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Advanced Member Group: Members Posts: 2,422 Joined: 18-April 05 From: Pasadena, CA Member No.: 3,946 Region Association: Southern California |
So once I got my 2056cc built the tach could no longer keep up and just flailed around worthlessly... Especially when running an autocross. So I finally got around to trying the 2200uF trick and now it's over damped... Sigh. Maybe I'll try a different variant of capacitor and see what happens.
Anybody else have a recommended type of capacitor for the application: http://en.wikipedia.org/wiki/Types_of_capacitor |
Spoke |
May 11 2010, 07:40 AM
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#2
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Jerry Group: Members Posts: 6,991 Joined: 29-October 04 From: Allentown, PA Member No.: 3,031 Region Association: None |
The right capacitor is not an exact science. What it does can be seen below. The oscillatory response is what the stock tach does since it is under-damped. The step function is what you want but is basically unattainable.
The critically damped response is the one that gets to the desired level as fast as possible without overshooting. The overdamped response which is what you seem to have just takes too long to get to the right RPM. Lowering the value of the cap should help. I tested mine before reassembling the tach. Attached image(s) |
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