Low cost and stable capacitance level the probe installed in the transparent tube. In the pipe find two capacitance sensors. One has been built in on the beginning, and other at the end tubes. Has been envisaged the orthogonal fitting in. When the level liquids come to the first sensor (40mm from the edge) activates his NPN output. When the level liquids grow to the other sensor (710mm from the edge), activates and other NPN output. The every capacitance sensor LED indicates the activity.
Warning: plexiglass is not good the material for the tube because of too big porosity for the humidity! If would use plexiglass then the pipe must is opened on both ends because of the prevention of condensation of humidity.
Power supply: 24V= / 18mA
Output: NPN, 50mA every
Low level: 40mm..620mm
High level: 130..710mm
Dimensions: 30 * 790mm
Dimension of sensor: 91 * 23mm
The temperature region: 0..60°C (are tested)
Price of finished complex (flueless): 400 HRK (53 euro)
Detail: probe activated by finger (across 3mm thick tubes walls)
integrations in of sensors in the pipe of other lengths
building in one or more capacitance the sensor
buildings in of sensors in the different housing - mins.
dimension electronics are (l * w * h): 55 * 16 * 10mm, sensor 2cm2