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Tired of looking in my tank and guessing if I have enough fuel for a cruise. We use capacitive sensors in aviation to measure fuel level since they are dead reliable and no moving parts. I'll need some help from my EEs to provide output for my stock fuel gage. I'll machine a flange to match the stock tank flange and gasket as the adapter for the sensor. This is what the sensor looks like. If anyone knows of something like this existing for the C2 let me know. Thanks Larry
I used one of the tube type fuel senders in the fuel cell on my '59. http://www.carols62.com/59/oct14.htm
If the Classic Instruments sender is like the one I used it contains a float with a magnet inside the tube which varies the resistance by turning reed switches on/off as it slides up and down. In my case there were 8 reed switches and 8 resistors so the best resolution I could get was 1/8 of a tank increments. I'm not sure how Lostofcubes' capacitive sensors work but they probably give much better resolution than the tube with the float inside.
Charles
Capacitive sensors are basically a tube within a tube. The fuel level fills the volume between the inside of the outer tube and outside of the inner tube. The capacitance change with fuel level is calibrated to provide the gage voltage. My Corvette collector friend has a tank I'll measure the depth of next week to order a sensor. I already have several bad sensors I can use to design the tank adapter. The acknowledged best source for our sender in Atlanta has stopped production and his were made in China. I'll post status. Larry
First a somewhat obvious question (to me anyway....) Why not just use a the standard resistive sender?
I used to run the engineering dept at a small aerospace company where we made both resistive and capacitive fuel measurement systems for general aviation. As was stated earlier, the concentric tubes of the probe form a capacitor using the fuel as the dielectric. These probes are typically one part of a variable frequency circuit - as the probe capacitance changes, the frequency of the circuit changes accordingly. You'll need to convert that frequency to a voltage (or current) to drive the meter you want to use.
Those days are long behind me. Economy took us out back in 2010 and we sold the company - had a good run for 13 years. Grew it from four guys in a barn to 40 in a 26k ft facility.
If you run av gas maybe you need a fuel flow gauge instead calibrated in lbs/hr...... Pilots always told us that the fuel qty gauge was secondary, they relied on the fuel flow gauge more.
First a somewhat obvious question (to me anyway....) Why not just use a the standard resistive sender?
If you run av gas maybe you need a fuel flow gauge instead calibrated in lbs/hr...... Pilots always told us that the fuel qty gauge was secondary, they relied on the fuel flow gauge more.
Tom
I bought, drained, and installed two which indicated correct ohms, but then didn’t work with the gage. Gage rebuilt. Solution? Wood dowel. I was going to give resistive another try from K&B but he retired and shut down. And he had his good ones made in China.
I didn’t trust either when flying and when all tanks registered 1/4 we looked for an airport. But the four capacitive sensors after calibration were reliable and accurate. PM the name of the business. May have bought stuff from you. Too bad about the business Tom.
cb, Don’t know yet. Chatted with one EE on my way out today. But the tiny computers today are amazing. We’re using Raspberry PIs everywhere gathering data and they’re dirt cheap. But I’m certain once the capacitive sensor is installed I’ll never have to drain gas again to debug. Then it will be the 55 YO gage. Gage needs 0-120 ohms. I’ll let u know.
I need to find the paper John Z wrote on our fuel level system. He said it sucked. Increasing max ohms to 120 helped. Cheers
cb, Don’t know yet. Chatted with one EE on my way out today. But the tiny computers today are amazing. We’re using Raspberry PIs everywhere gathering data and they’re dirt cheap. But I’m certain once the capacitive sensor is installed I’ll never have to drain gas again to debug. Then it will be the 55 YO gage. Gage needs 0-120 ohms. I’ll let u know.
Originally Posted by Lotsacubes
The EE found me a fuel meter interface. Programmable ohm output from sensor input. Used to match sensors and various gages. More to come.
From your description I think I could build the hardware with not too much trouble.
When I asked about the circuitry I had in mind using one of the micro computers to handle the interface. I have used the Arduino micro computer to do some traction control programming. I think the Raspberry is a little more advanced, but as long as I can program it in 'C' I will be OK. I am interested to see what the interface looks like.
Charles
cb, I’m finding capacitive fuel level sensors with various and tunable outputs. Some companies offer programmable resistance ranges apparently at the sensor. Monday as time allows I’ll start calling. This may be way easier than I imagined. But many options offer for aviation and transportation. I don’t think any programming will be necessary. I’m finding some capacitive sensors specifically to replace float resistance type senders for older vehicles. More after research calls. My friend has an empty fuel tank I can measure sensor length. More to follow.
Capacitive Fuel Level Sensor for C2
Pilots always told us that the fuel qty gauge was secondary, they relied on the fuel flow gauge more.
