Al, A zener diode can provide a standoff voltage. Use the resistor divider to get a voltage small enough to work with. I can't take the time for the design. At the equivalent of the low voltage, an x volt zener connected to the low side of the meter won't conduct until the zener voltage is exceeded so it will "stick" at zero for "empty". The full scale current then must be such that the "high voltage" current is enough to read "full". That depends upon the meter internal resistance, which you can measure. Car stuff is usually rather low resistance. A different meter might be better (maybe).
Sorry, but I must get on to other things. Frank -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Al Lococo Sent: Thursday, January 17, 2008 3:59 PM To: [email protected] Subject: [FLEAA] Introduction Hi, My name is Al Lococo. I just joined the Florida EAA. I was a former member of the National EAA in the late 70's and early 80's when I converted my first EV which I now call EPT1 (Electric Pickup Truck one). At the time I lived in Wappingers Falls, NY. http://www.lococo.org/Electric%20Truck/72%20Dat.htm Contrary to Shawn's post, I am from Winter Haven ;-). My recently completed vehicle is a 99 Ford Ranger which I call EPT2. http://www.lococo.org/Electric%20Truck/Truck.htm This page contains pictures and a link to my documentation and a video. The video is in DVD format. I am looking for someone to convert it to mpg format. My next addition to my truck will be to make the fuel gauge reflect the battery voltage in a form that is meaningful to the unsophisticated. You know full and empty. I want empty to be 144 Volts and full to be 155 Volts. The gauge has a 22 ohm to 145 ohm range on the input from the float in the old fuel tank. I want an opto coupler and something to invert the voltages between 144 and 155. I plan to do some tests to get started us a voltage divider using resistors. I think this will run the meter backwards rising from empty to full. Anyway if someone has solve this problem I am interested. I am also interested in comments criticism and suggestion concerning the choices I have made in my design and implementation. Cheers, Al Lococo _______________________________________________ Florida EAA mailing list [email protected] http://www.floridaeaa.org _______________________________________________ Florida EAA mailing list [email protected] http://www.floridaeaa.org
