Date:         Tue, 29 Sep 2009 09:22:50 -0700
Reply-To:     Rocket J Squirrel <camping.elliott@GMAIL.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Rocket J Squirrel <camping.elliott@GMAIL.COM>
Subject:      Re: ARRRGGGHHH Re: Tantalum capacitors to stop blinking temp  LED
Comments: To: David Beierl <dbeierl@attglobal.net>
In-Reply-To:  <4ac22fc7.0407560a.05a4.2112@mx.google.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Ah well then -- never mind.
--
Mike "Rocket J Squirrel" Elliott
84 Westfalia: Mellow Yellow ("The Electrical Banana")
74 Westrailia: (Ladybug Trailer company, San Juan Capistrano, Calif.)
Bend, OR
KG6RCR



On 9/29/2009 9:03 AM David Beierl wrote:

> 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
>
>