If you want to measure capacitance for a sensor some distance away, you can't do it at the end of long wires. Just temperature changes and nearby objects will make larger changes that can swamp what you are trying to measure.
This was originally for my first car in the late '70s. I put sensors on the windshield washer tank, the radiator hose, even inside the gas tank. I had already designed and built my own precision capacitance meter using two 555 timers. This triggered each sensor separately, then sorted which one was active with a decade counter and an LM3914 linear dot/display driver.
This was originally for my first car in the late '70s. I put sensors on the windshield washer tank, the radiator hose, even inside the gas tank. I had already designed and built my own precision capacitance meter using two 555 timers. This triggered each sensor separately, then sorted which one was active with a decade counter and an LM3914 linear dot/display driver.
Two wire twisted pair is a lot cheaper than 3 wire. And when you aren't flush with cash, that can make a difference. This one is designed to send the signal back to an Arduino, which is then programmed to measure just the On time.
I've used this to measure liquid levels in water tanks, on roofs, even inkjet tanks. The sensor itself might be metal tape on the outside of a plastic or glass tank, or insulated wire in the liquid. Make sure the insulation is compatible with the liquid.
One 555 timer goes onto the remote sensor. The signal and power travel on the same line similar to how I2C and several other methods work, although in this case there are no addresses.
I've used this to measure liquid levels in water tanks, on roofs, even inkjet tanks. The sensor itself might be metal tape on the outside of a plastic or glass tank, or insulated wire in the liquid. Make sure the insulation is compatible with the liquid.
One 555 timer goes onto the remote sensor. The signal and power travel on the same line similar to how I2C and several other methods work, although in this case there are no addresses.
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