Do you remember Potentiometer?
Potentiometer and encoder are both electromechanical devices that can measure position.
The difference is that the potentiometer outputs analog signals whereas the encoder provides
digital signals. Generally speaking, potentiometer has shorter life and low accuracy compared to
its counterpart. But would that make encoder the best choice for all occasions?
If you are currently using an encoder with standard 10 bit resolution, its accuracy is roughly the
same as a potentiometer with linearity ± 0.1%.
Many encoder users find it troublesome with its specific requirement for installation. If decentering
or backlash of shaft occur, it can lower the accuracy down to 2 to 3 bit. In that case, potentiometer
has a higher accuracy, even including repeatability, over encoder with 14 bit or less resolution.
Encoders with 16 or more bit resolution are now available in the market. Evidently, its position
measurement is by far more accurate than potentiometer. However, higher resolution means larger
housing size. Potentiometer on the contrary, maintains its housing size regardless of the accuracy level.
Not to mention that contactless potentiometers can be applied in considerably small-scale design.
When we compare life, conductive plastic potentiometer and other contact type potentiometer may have
shorter life. But Hall-IC and MR-element contactless potentiometers have longer life span, very much
Commercial and industrial machinery operated with digital signals are becoming more dominant. It is
inevitable for higher demand and enhancement of technical innovation for encoder. Despite all the
digitalization, potentiometer still has the following merits over encoder.
1. Potentiometer produces sufficient amount of output without using the amplifier.
2. Potentiometer can be wired with 3 terminals.
3. Potentiometer is easy to install. For encoder, even a slight misalignment of shaft can affect
accuracy and hysteresis.
4. Potentiometer is smaller in size and has a superior ability in measuring narrow angles.
5. The unit cost of potentiometer and accompanying circuits are inexpensive.
6. Low Current Consumption.
7. Shorter lead-time.
When you recall all the merits of potentiometer, there are times when it is best to use potentiometer rather
than encoder. You can even apply these two devices together, using potentiometer as a backup for encoder to
draw machine's maximum capacity.