Date:         Tue, 29 Sep 2009 12:03:12 -0400
Reply-To:     David Beierl <dbeierl@ATTGLOBAL.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         David Beierl <dbeierl@ATTGLOBAL.NET>
Subject:      Re: ARRRGGGHHH Re: Tantalum capacitors to stop blinking temp LED
Comments: To: Rocket J Squirrel <camping.elliott@GMAIL.COM>
In-Reply-To:  <4AC21E24.8050200@gmail.com>
Content-Type: text/plain; charset="us-ascii"; format=flowed

At 10:48 AM 9/29/2009, Rocket J Squirrel wrote:
>That's not the same as a 0pf capacitor. It's the same as a resistor, and
>if the capacitor is being charged through another resistor until it
>reaches the shutoff trigger voltage, and that capacitor is paralleled with
>a resistor to model the internal leakage (or schmutz on the board, the
>proposed "external" portion of the leakage) then you got a voltage divider
>which will prevent the voltage at the top of the cap from ever reaching
>blink-o-matic shutoff voltage.

Mike's talking about removing the cap entirely, so aside from the
fact that the newer level controllers *need* that timed blink, the
only issue would be leakage across the board, which isn't enough to
matter by itself.  The current source for the cap would drive the
chip high directly.  Of course that might inhibit the blink
completely, probably would I think -- can't remember the circuit well
enough.  But it's moot because of the controllers.

:-)
d