BruceMe
Well Known Member
There's a few turn-key product solutions you can spend couple hundred on and get a "bingo-fuel" warning system. They are a great, highly accurate and reliable backup to the gauges and I've heard good things about them. But it was a compelling and simple electronics project.
How they work... The sensors are a commodity item. You can get them online, I bought mine for $15 for three. Search for "Optical Liquid Level Sensor Switch". The physical working principal is that light refracts off of a liquid differently than a gas (air/vapor). The sensor is an all-in-one unit requiring a 5v source/ground and outputs either while in liquid it outputs no signal (low/ground) or in gas/air/vapor (high/5v). The unit I purchased came with a data sheet and claims it was capable of passing 10ma of current through it when triggered.
10ma is not a lot of current, but it could directly drive a small LED (relatively dimly) with a current limiting resistor. Pull 5V off your USB, one each of; sensor, led and resistor, a bit of soldering and that's it!
In my case I am going to connect them to one of the user-defined inputs in my G3X. It will show a FUEL-L or FUEL-R warning in RED on the PFD. But I also tried connected it to a ATTiny85 to drive bigger brighter LEDs and to test the sensors. That worked much better and wasn't at all hard.
As for mounting, I should have been more exacting... but I saw where others installed them and put mine in the same basic pace on the inboard baffle about 60mm from the bottom. I'll measure the fuel until the light goes off and placard the fuel valve with whatever that is... something between 2-4g I suspect.
Enjoy!
How they work... The sensors are a commodity item. You can get them online, I bought mine for $15 for three. Search for "Optical Liquid Level Sensor Switch". The physical working principal is that light refracts off of a liquid differently than a gas (air/vapor). The sensor is an all-in-one unit requiring a 5v source/ground and outputs either while in liquid it outputs no signal (low/ground) or in gas/air/vapor (high/5v). The unit I purchased came with a data sheet and claims it was capable of passing 10ma of current through it when triggered.
10ma is not a lot of current, but it could directly drive a small LED (relatively dimly) with a current limiting resistor. Pull 5V off your USB, one each of; sensor, led and resistor, a bit of soldering and that's it!
In my case I am going to connect them to one of the user-defined inputs in my G3X. It will show a FUEL-L or FUEL-R warning in RED on the PFD. But I also tried connected it to a ATTiny85 to drive bigger brighter LEDs and to test the sensors. That worked much better and wasn't at all hard.
As for mounting, I should have been more exacting... but I saw where others installed them and put mine in the same basic pace on the inboard baffle about 60mm from the bottom. I'll measure the fuel until the light goes off and placard the fuel valve with whatever that is... something between 2-4g I suspect.
Enjoy!
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