Mailing List Message #26222
From: Ed Anderson <>
Subject: Analog Digital system comparison
Date: Sun, 28 Aug 2005 10:28:18 -0400
To: Rotary motors in aircraft <>
This may be of interest to some.
Here are photos of my two fuel monitoring systems, comparing the original Analog system with the new Digital System.
The analog system served long and well, giving accuracy of fuel flow and fuel used to less than a 1% error.  However, it was large, had 9 chips and only provided two bits of data - Fuel Flow and Fuel Used as displayed information.  Any change required a change to the design, new chips and a new board.  Very limited upgrade capability and just outdated (well, it actually was when I designed it - but, being an old analog type myself,  it was a interim system until I could learn a bit about this digital world)
The digit system is much smaller, the one shown used 2 chips (since reduced to one chip- the microprocessor) and provides 9 different fuel factors (including Air/Fuel ratio indication), has user settable alarms, remembers fuel parameters at shut down and has an automatic calibration system. Software changes can be easily (relative speaking) make to accommodate changes and upgrades.  Currently waiting for a new board for version 2 of the digital - this one will have a larger LCD screen (but will still fit 2 1/4" hole) with graphical capability which I hope to be able to display the EC2 fuel map in graphical form.  The activation buttons will be re-positioned so that even my fat fingers can better push them. 
So after many years of use - old reliable (but out-dated) analog system is being retired with honors.
Ed Anderson
Rv-6A N494BW Rotary Powered
Matthews, NC
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