It might appear that little has changed with potentiometer technology for years, but this is untrue, especially with the emergence of the Spectra Symbol Membrane Softpot and Hotpot potentiometers from Variohm Eurosensor.
The Softpot and Hotpot membrane potentiometers are based on the principle of a voltage divider. They can measure multiple of linear and rotary angles because the product is printed on a substrate. As a result, almost any design can be achieved. The system is claimed to be impervious to electromagnetic radiation and is sealed at IP66.
While the Softpot is able to function at temperatures of up to +60 degrees C, the Hotpot can withstand temperatures as high as +125 degrees C. Consequently the Hotpot presents new possibilities for many industrial and automotive applications because of the heat capabilities and the durability (in excess of 10 million cycles or more than 20 million dithers).
The sensors are constructed with a printed element on a bottom layer, then a spacer mounted area around the element, followed by a top collector. By depressing the top layer to connect with the bottom element, a voltage divider signal will be created. This construction avoids the scraping that occurs with a wiper potentiometer because there is no wiper in direct contact with the element; rather there is a rolling or sliding motion on the top circuit layer.
Because of this construction, no debris, dirt or water can enter the conductive area - the spacer creates a sealed environment. When a regular potentiometer is sealed, this often increases the torque and makes the unit costly to set up. The force sensitivity for the traditional wiper is also avoided, as there is a range of forces that can successfully be applied to the membrane sensors.
The membrane potentiometer is just like a wiper potentiometer, conductive plastic potentiometer or other similar device in its basic form, except that it is sealed and uses a different wiper system.
An increased wiper force required for the membrane potentiometer ranges from 85 grams to 200 grams, which significantly enhances the unit's ability to withstand shock and vibration. The traditional potentiometer has problems due to the light force; thus the membrane potentiometer adds a level of stability to the sensor system through its wiper construction.
Shaftless potentiometers are difficult to seal and have to balance radial and axial forces. Due to the membrane potentiometer construction, no shaft balancing is required, and the lower material requirements make the membrane pot more cost-efficient.
Ultimately, one of the greatest drivers on the market is the cost. There is a significant cost improvement with the membrane potentiometer in comparison with the alternatives; however, there are even more savings available when considering the application of the sensor. For example, instead of adding multiple fixtures to ensure the placement of a bulky potentiometer, the 0.5mm membrane potentiometer can fit into almost any design without compromising the construction of the system.
For more information, visit www.variohm.com
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