[simpits-tech] Driving a 28vdc fuel indicator

[Joseph Fagner]

Most of these things are 400Hz gauges since they are used in aircraft.  I 
suspect you need 28v 400Hz.  Then you have to generate a signal and that has to 
be calibrated along with feedback to know the needles position. Without the 
schematic, you will need to pull everything apart and trace out the wires and 
parts.  If you are going to do that, you're better off gutting it and going with 
an aircore.  Or, you keep the motor and drive it with custom electronics.

Jay




________________________________
From: "dabigboy at cox.net" <dabigboy at cox.net>
To: Simulator Cockpit Builder's List <simpits-tech at simpits.org>
Sent: Sun, April 7, 2013 7:54:42 PM
Subject: [simpits-tech] Driving a 28vdc fuel indicator

I am having a rough time with something that was supposed to be simple. I picked 
up a 28v fuel indicator made by Liquidometer a while back. I can't find any 
documentation for it, but putting voltage to two of its 10 pins moves the 
needle. In fact, I can pretty well control the needle using 12v PWM (or variable 
voltage, basically) on an Arduino, with a PNP transistor, up to about half scale 
needle deflection. Beyond that, the needle barely moves, even with DOUBLE the 
voltage (30+ volts). I tried additionally putting voltage to other pins (there 
are a number of pins that will move the needle in much the same manner), but 
nothing pushes it over the magic halfway'ish point.

Any ideas? I have a gauge just like this:  http://www.ebay.com/itm/110894737604

I am about ready to gut it and stuff an air core motor in there, but I hate to 
butcher the gauge.

Matt
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