This sounds neat, but I worry that if we're measuring capacitance, then external influences may throw off the calibration. For example, when I first saw this post, I related it to a problem I had building a corner scale for a vehicle. It is very necessary to keep the wheels level. I wonder how the large chunk of metal in the area (the car) will affect the sensor output. Cheers, -Neil. -----Original Message----- From: pic microcontroller discussion list [mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Martin Farrell Sent: Wednesday, July 10, 2002 5:32 PM To: PICLIST@MITVMA.MIT.EDU Subject: Re: [EE]: Electronic Level Sensor In message , Pic Dude writes >Another option... > >I really like water levels, as they are "self-calibrating". >Perhaps you can use something based on that. For example, >use a hose with a water-level sensor on both ends. This >could be something ultrasonic, something optical on the >outside with colored water, or electrodes in the water, etc. >And you'd need 2 such arrangements to level a platform with >3 adjust points, or 3 arrangements if you have 4 adjustment >points. > A good way of making a non contact sensor for water is to make an oscillator with a 74HC14 with 1M feedback and a self adhesive metal tape round the pipe as the capacitor.(No 'physical' ground is required). Count the frequency with a PIC. I've used a 12CE518 storing the smoothed trip count (level) in EEPROM on whirlpool bath level monitors with no problems. -- Martin Farrell -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu