Using Capacitance-to-Digital converters AD7150 or AD7747 to measure fluid levels I'm looking to measure the fluid inside a polyethylene waste holding tank with walls 10 mm thick. This is typical of a boat or RV. I'd like to measure using proximity sensing capabilities of Capacitance-to-Digital converters, which have no direct contact with liquid, are highly accurate and have low current requirements. Analog Devices makes two sensors, AD7150 and AD7747 that might work based on the specs I've read, but I don't know if they'll measure through the holding tank walls. If anyone knows if either of these would work, or has any other suggestions I'd appreciate your advice. Thanks.
Sounds like a fun project. Why not try the EVAL-AD7150EBZ is a fully featured evaluation board for the AD7150. The evaluation board can be operated in standalone mode ( either battery-powered or with external power supply) or connected to a PC via a standard USB interface. When operated with a PC, software is provided enabling the user to perform detailed analysis of the CDC's performance. This software includes the technical note describing the operation and set up of the evaluation board. Also how you package the sensor will have a big impact on how it works.