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TUTORIAL OVERVIEW Whether you’re building a small robot or using any kind of motors in your projects, it might be useful to know the speed at which your are driving them. In this tutorial we will see how to connect and use an infrared speed sensor based on the LM393 chip. The speed sensor uses a disc with holes (encoder disc) to block the infrared beam, thus by counting the number of times the sensors goes from Low to High we can calculate the number of revolution for a given time period. For our tutorial we will count the number of time the speed sensor goes from Low to High in a second and then divide that number by 20 (number of holes in the encoder disc) to get the number of revolution per second. CONNECTIONS The speed sensor uses only 1 pin that goes from Low to High to detect holes in the encoder disc. Since we will be using Interrupt zero to read the speed sensor, we need to connect it to Pin 2 (interrupt 0 pin) on the UNO. Were are also using the

DHT11 is a  Humidity  and Temperature Sensor, which generates calibrated digital output. DHT11 can be interface with any microcontroller like Arduino, Raspberry Pi, etc. and get instantaneous results. DHT11 is a low cost humidity and temperature sensor which provides high reliability and long term stability. In this project, we will build a small circuit to interface Arduino with DHT11 Temperature and Humidity Sensor. One of the main applications of connecting DTH11 sensor with Arduino is weather monitoring. We have already seen about humidity, relative humidity, humidity sensors and their types in this article. Table of Contents Circuit Diagram Components Required Circuit Description Component Description DHT11 Temperature and Humidity Sensor Example Working of the Project CODE Applications Construction and Output Video Circuit Diagram The following circuit diagram shows all the necessary connections required to implemen