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## Re: Slowing the Fuel Gauge Fluctuation on an LBC

 To: "MG List" Re: Slowing the Fuel Gauge Fluctuation on an LBC "Tim Economu" Mon, 23 Aug 1999 09:51:02 -0700
 ```Paul: Remember that one time constant is the time used to go 63% of the total voltage swing. One time constant is equal to the resistance times the capacitance: So, t = RC for 40 ohms, and 5000 microfarads, one time constant = 0.2 sec for 40 ohms, and 10000 microfarads, one time constant = 0.4 sec for 20 ohms, and 5000 microfarads, one time constant = 0.1 sec for 20 ohms, and 10000 microfarads, one time constant = 0.2 sec But notice also that: for 10,000 ohms, and 10 microfarads, one time constant = 0.1 sec These former are all large capacitors and fairly short time constants. The capacitor can be reduced and resistor increased as later shown to make the capacitor small, and small also means a better dielectric material can be used (like tantalum) for longer life. The electrolyte in electrolytic capacitors dries out in time and the cap becomes useless. OR.... you can just live with it!! (My recommendation) Kind regards, Tim Economu phone: 360-579-2117 Design Engineer fax: 360-579-2117 Trace Engineering email: economu@whidbey.com 4131 Springwater Clinton, WA 98236 >>Paul said: ------------------------------ Date: Fri, 20 Aug 1999 20:21:45 +0100 From: "Paul Hunt" Subject: Re: Slowing the Fuel Gauge Fluctuation on an LBC Don't know about non-hot-wire gauges but hot-wire gauges have an impedance of just a few tens of ohms. Haven't done any time contant calculations in a long while but if LC = seconds then we are talking about 5,000 micro-Farads for 1/10th sec. PaulH. >> ```
 Current Thread Slowing the Fuel Gauge Fluctuation on an LBC, Wildbil923 Re: Slowing the Fuel Gauge Fluctuation on an LBC, Larry Colen RE: Slowing the Fuel Gauge Fluctuation on an LBC, Hans Duinhoven RE: Slowing the Fuel Gauge Fluctuation on an LBC, Barney Gaylord Re: Slowing the Fuel Gauge Fluctuation on an LBC, REwald9535 Re: Slowing the Fuel Gauge Fluctuation on an LBC, Paul Hunt Re: Slowing the Fuel Gauge Fluctuation on an LBC, Paul Hunt Re: Slowing the Fuel Gauge Fluctuation on an LBC, glen Re: Slowing the Fuel Gauge Fluctuation on an LBC, Barney Gaylord Re: Slowing the Fuel Gauge Fluctuation on an LBC, Tim Economu <=