Potentiometers, Optical Angular encoders, Magnetic rotary encoders, linear encoder… What will be the next?

  Potentiometers, Optical Angular encoders, Magnetic rotary encoders, Linear encoder… What will be the next?

  Catching the Knob of your microwave over or hi-end home theater system, you probably are asking yourself not once, what is situated behind the “false board”. In the most common case, there is an encoder.

  Some old or old-fashioned receiver system has self-rotating Volume Knob, using a servo motor, doing this activity.

  Nowadays, the rotary variable resistors – Pots. or potentiometers are commonly used in budget device sector. It is the cheapest way to get the angular position of the rotating axis.

  As the cheapest way to get the angular position of a knob, adjusting volume or tone correction in EQ, Setting the Voltage, Current limit in Power Supply devices, Frequency, Duty cycle, or Period settings control in some equipment measuring tools.

  But,… again this conditional word, always existing, when is coming word for durability, and lifespan of the unit.

  Potentiometer – viewed as a mechanical device along with its main benefits – the low-cost, ease of use, have and disadvantages: as limited power, limited count cycles of rotations, connected with mechanical contact bounce and noises related to an abrasion,

  The problem with nonlinearity it is not too significant, but it exists.

  Definition: The potentiometer is a passive device with an adjustable resistance of one or two sections, which resistance is depending proportionally the rotating axis angle.

  Example: The servo mechanisms are using feedbacks. In common case, they have an analog Resistive output. It represents the angle to Resistance axis relation of single or multi-turn Potentiometer. The simple projects with a low loading mechanics can use the resistive feedback. The potentiometers have the typical lifespan between 5,000 and 50,000 rotation cycles, as a maximal count is for the best and expensive members.

  Encoder: What does the word encoder mean?

  Definition: The encoder is an electromechanical system, who can measure displacement.

  In common case, this is multi pairs of optically connected light emitting & receiving devices, situated on two sides of the specially coded disc or a ruler, for linear type encoders.

  There are tens types of Angular Encoders, but, the Optical Angular encoders as a whole, can be divided, in two groups:

  • The Absolute Angle Encoders and,
  • The Incremental Angle Encoders.


PIC. 2 Gray Code Encoder


  See the encoder disc in PIC. 2  Easy can be understood the principle of work if you assume three pairs of Led Emitting Diode and Photo Transistor, projecting one by one in a transparent area, radially from the center to periphery. Lighted Photo Transistor is saturated and voltage drop on its silicon structure is negligible. As result three lighted output transistors represent position Zero (000), If they are both in dark, the position is Seven (111B). The middle sensor is lighted, peripheral are in dark, represents the Position Five (101B).

  The typical High-Resolution Encoder Using are implemented into Comfortable Surface DIAL in Microsoft Surface Studio Set.


PIC. 3  Surface Dial – Rotate and Click. Dial Diameter: 59 mm


AMAZON.CO.UK Affiliate Link: Microsoft Surface Studio – Ultimate Jog Dial:


Hardware-Pro.Com Internal Link:  Surface Studio: Complete Solution For Art Creators By Microsoft


 What will be the next?

  What will be the next?

  The future is in a laser detecting technology. Nowadays this technology is more expensive, but the reached high results overcome the price.

  Example: Renishaw RLU20 Unit is using (Helium-Neon) Laser Source with stability ±2 ppb for a random hour period,

  If the design needs movement distance below 1m, listed Detector can extract sinusoidal signal output with period 158 nm! This is not the end: Using 36-bit parallel interpolator PRI20, the reached resolution is: 38.6 pm (picometers) with up to 1m/s velocity, which is an unbelievable result.


Don’t Stop To Reinvent Yourself, Dear Explorers!