This page will discuss a variety of sensors, explaining how they work and how they can be used in circuits.
The ultrasonic sensor is a sensor that uses sound to measure the distance, this is done by having a transmitter and receiver. The transmitter will send and pulse and the time it takes before receiving the signal can be used to calculate the distance. The sensor can be looked at in 2 parts. The first part is the transmitter, this part will need to send some unique frequency to the sensor, however, this signal must be amplified heavily to increase the distance of the sensor. The signal being sent should also be sent for some given time so that the receiver can have time to distinguish its signal. The second part is the receiving end. The signal must first be amplified and compared to the unique frequency that was sent. If the signal was the correct frequency, the module can do what it wants to notify the user.
The laser sensors operate as the same principle as the ultrasonic sensors to measure distance, but this time light. When it comes to performance, laser sensors are more robust and accurate, but more expensive.
There are a wide variety of thermistors but there are three main thermistors. The chart below is a great representation of the types of sensors. Here is the link to the website: link Look at this link for most popular temperature modules: link
Humidity sensors are used to measure the moisture in some median. The output of these sensors is usually in the form of altering some electrical property. The website here shows a great explanation of the different types of humidity sensors: link Here is a link to a popular humidity sensor: link
There are two main types of rotary encoder: absolute and incremental.
- Absolute gives out an exact position of the rotor, this information can be sent through a digital signal or analog signal.
- Incremental gives out a signal letting the receiver know that the rotor is rotating in some direction.
Potentiometers are just simple voltage dividers where the resistors are both separated through a variable resistor. The middle terminal that divides the resistors gives out a percentage of the voltage input depending on the resistance value. This works best when a controller or amplifier needs a variable voltage signal. These devices are also good for just a variable resistor by just using two of the three prongs.
This sensor converts some kind of tension to an electrical signal. There are many methods that can be used to achieve this but the datasheets should be read on the specific sensor.
Passive Infrared sensor
These sensors are mostly used to detect motion by something that gives off heat. The Passive means that this type of sensor doesn’t need to send out anything to read movement. These signals also do not tell the user what is moving or where it is moving.