Question
Does anyone have any ideas on how I can use RPI with ADC to measure a tank level sensor which has a range of only 20 to 200 ohm?
*** Answer***
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Long Answer
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Introduction and Summary
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Question Analysis
I think the preliminary functional spec of the project is very good, because it is concise and precise.
There are many reasons that the question is so short, but I will not list my wild guesses for now. Perhaps later.
The spec includes the following key words/phrases:
"Rpi, ADC, tank level sensor, 20Ω ~ 200Ω.
The word "tank", is crucial. She says "tank", not "container", perhaps she wants to indicate that the "tank" is deep , say, not a 5 inches deep fish "bowl" or "pond".
The phrase "20Ω ~ 200Ω" is also crucial. There are basically two types of liquid level sensors: active and inactive. Active sensors are usually 5V or 12V powered, and the sensor output is a DC voltage level. Inactive sensors don't have any power. Usually the sensor is just a reed switch and floating magnet, or a long "resistor" whose resistance varies as the water level. Usually the resistor is far, perhaps 10ft, and up to 1,000 ft from the measuring instrument.
References
Gig (ee, rpi, arduino) projects
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