A light source and photosensor combine for effective, reliable, non-contact proximity detection of nearby objects. Part 1 of this article looked at the principles and three basic approaches to optical proximity sensing, also called photoelectric sensing. This part looks at physical implementations of the system, input/output specifics, and other considerations. Q: Is this a relatively […]
FAQ on optical proximity sensing: part 1
A light source and photosensor combine for effective, reliable, non-contact proximity detection of nearby objects. Non-contact proximity sensors detect the presence or absence of nearby objects (including animals and people) using basic physics phenomena such as capacitive and inductive electromagnetic fields, light, or sound. Many techniques are used for this sensing, each offering different operational […]
What are magnetic rotary encoders?
Part 1 of this FAQ looked at the optical rotary encoder, a low-cost, high-resolution, easy-to-use sensor for indicating incremental shaft position (although it can be “upgraded” to indicate absolute position as well). Q: What is the basic principle of the magnetic encoder? A: The magnetic encoder uses a rotating gear made of ferrous metal, and […]
What are optical rotary encoders?
Accurate measurement of rotary shaft motion, including position, velocity, and acceleration, is crucial in numerous applications. This is typically achieved by incorporating a rotary encoder into the motor or shaft assembly. While “rotary encoder” is often abbreviated to “encoder,” it should not be confused with other electromechanical or electronic encoding devices used for data format […]
FAQ on thermistors for temperature sensing
The thermistor is a widely used temperature sensor and an attractive alternative to thermocouples and RTDs — but only in some applications. Temperature is the most commonly assessed and measured physical parameter if you add all the consumer, industrial, commercial, medical, food-related, product tests and measurements and other places where it needs to be sensed. […]
Automotive airflow analysis reveals virtues & limits of sensors, models, and simulations
Design verification requires both sophisticated models and the simulation they offer, as well as real-world validation of their results. Sensors and sensing for real-world physical parameters form a large part of the electronics scene, but it’s easy to confuse the two. A senior project leader I once worked with always reminded us that “sensors are […]
The why and how of 4-wire Kelvin sensing: part 2
Early electricity investigators cleverly solved the challenge of measuring milliohm resistances or microvolt changes in voltage across a resistor over 150 years ago. This part continues the exploration of 4-wire Kelvin sensing. Read Part 1 here. Q: What did Lord Kelvin do? A: He realized that using a single combined path for forcing the current […]
The why and how of 4-wire Kelvin sensing: part 1
Early electricity investigators cleverly solved the challenge of measuring milliohm resistances or microvolt changes in voltage across a resistor over 150 years ago. Engineers, scientists, and researchers must often reduce imperfections and associated inaccuracies in test and measurement situations. Among the techniques they have used to do this are: Use better, more accurate components with […]
FAQ on railroad hot-box-temperature sensing: part 2
Modern electronics should be able to easily solve a temperature-sensing challenge, but the harsh real-world complexities make it a difficult proposition. Part 1 of this article looked at the basic issues of railway bearing failure and detecting these before they happen. This part looks into more details and sensing options. Q: What can the railroad […]
FAQ on railroad hot-box-temperature sensing: part 1
Modern electronics should be able to easily solve a temperature-sensing challenge, but the harsh real-world complexities make it a difficult proposition. Freight railroads are a very important part of the logistics infrastructure around the world for transporting raw materials as well as finished goods. They are a major constituent of intermodal transportation along with trucks, […]
