Torque is a rotational force produced when a vertical force is applied at some distance from the center axis of the rotating body. The familiar equation for torque is: Where: T = torque F = applied vertical force d = distance from axis of rotation In a DC motor, the output torque is directly proportional to the […]
What’s the difference between BLDC and synchronous AC motors?
The short answer is: brushless DC (BLDC) and synchronous AC motors are similar in construction and operation. Some manufacturers and experts even group them together as similar technologies, in the category of “permanent magnet synchronous motors.” Their key difference, however, lies in the stator coil windings and resulting back-EMF waveform of each motor. This gives them distinct performance […]
Pull-Up Resistor Basics
To understand a pull-up resistor, it helps to first understand how encoder output is generated. Incremental encoders can provide several types of digital output, with the three primary types being open collector, push-pull, and line driver. Open collector output is considered sinking, while the line driver type is considered sourcing, and push-pull output is both […]
The relationship between voltage and dc motor output speed
The operation of a DC motor is relatively straightforward. A coil is placed in a magnetic field, and when an electric current passes through the coil, a torque is produced, causing the motor to turn. The entire process is driven by applying electrical power to the coil, with the source voltage having a direct relationship […]
Ways to wire an absolute encoder into a motion system
Absolute encoders are traditionally wired in one of three ways: in parallel, with a serial interface, or over a bus. The serial and bus interfaces have multiple protocols or standards, some of which are open-source, while others are proprietary to specific manufacturers. When considering how to wire an absolute encoder, the required resolution, level of […]
FAQ: How do magnetic encoders work?
Encoders, whether rotary or linear, absolute or incremental, typically use one of two measuring principles—optical or magnetic. While optical encoders were, in the past, the primary choice for high resolution applications, improvements in magnetic encoder technology now allow them to achieve resolutions down to one micron, competing with optical technology in many applications. Magnetic technology […]
FAQ: What are stacked piezo actuators and what do they do?
A piezo element is a ceramic that expands or contracts when an electrical charge is applied, generating linear movement and force. Multiple piezo elements can be layered on top of each other, creating what is known as a stacked piezo actuator. These devices take advantage of the combined effect of each element’s expansion to produce a useful […]
What are capacitive encoders and where are they suitable?
Two types of encoders dominate the general industrial market—optical and magnetic. But capacitive encoders, a relatively new introduction, offer resolution comparable to optical devices, with the ruggedness of magnetic encoders. Currently, there are only a handful of vendors for capacitive encoders, but their suitability for applications requiring high precision and durability make them a good […]
Determining pulses per revolution for an encoder application
Incremental encoders determine rotary position by generating a specific number of pulses per revolution (PPR) and counting those pulses as the encoder spins. The PPR rating indicates resolution, and is typically the most important factor when selecting an incremental encoder. But how do you determine what PPR is needed for a specific application? Fortunately, establishing the required […]
FAQ: What’s the difference between single and multi-turn rotary encoders?
Absolute rotary encoders output precise position information—even after a power-off condition—by assigning a unique digital value, or “word,” to each shaft position. But in applications where the encoder makes more than one revolution during the process, there is no way to know how many turns it has completed. At least not with the traditional type […]
