There are occasions when a circuit needs to be fed with a square wave signal. To provide for such a scenario, we will build a square wave signal generator that uses a 555. A 555 can be configured to run in 3 different modes, the one that we are concerned with here is called the…
OBJECTIVE The objective of this project is to simulate a rolling die. I will use LEDs arranged in the pattern of a conventional die and give the illusion that it is ‘rolling’ as a number is randomly chosen. THE CODE The first thing that I did was to create and initialise an array, with the…
The problem There may be occasions when you have a microcontroller that does not have enough GPIO pins for a circuit! Your circuit may require a large number of switches or LEDs, which would use up lots of GPIO pins. It’s likely that you will need some of the GPIO pins for other parts of…
OBJECTIVE We will build an 8-bit binary counter. This means that it will be able to count from 0 to 255, which in binary is 00000000 to 11111111. An LED that is off will represent a binary 0 and an LED that is on will represent a binary 1. Since computers count in binary, this…
OBJECTIVE The objective of this project is a build a voltmeter that can measure voltages between 0 and 30V. I will use the analog inputs of an Arduino to measure the voltage, via a voltage divider. When an Arduino is powered from a 5V supply the maximum voltage that could be measured is 5V. However,…
OBJECTIVE In this project we will build a device for measuring temperature. THE HARDWARE You can use an UNO or MEGA There are a number of sensors that I could have used to make this thermometer but I chose the LM35. I chose the LM35 because of its precision. The LM35 has an output voltage…
THE OBJECTIVE Our objective is to build a frequency counter that can identify frequencies up to 1MHz. pulseIn() pulseIn() reads a pulse on a pin and waits for a change from HIGH to LOW or LOW to HIGH. This works with times that are between 10μs and 180s. You can provide either two or three…
OBJECTIVE We will build a passive infrared motion detector that can detect movement from distances that are between 3m and 7m. THE SCIENCE All objects that have a temperature above absolute zero (0 ° Kelvin/-273.15 ° C/-459.67 ° F) emit heat in the form of infrared radiation. The hotter the object is, the more radiation…
OBJECTIVE A range finder is a device that is used to find the distance between two points, using a technique known as ranging. In this project we will design and build a range finder that can measure how far away an object is, from 2 cm to 4 m (0.79 in to 13.12 ft). The…
OBJECTIVE For this project we will build a single traffic light that follows the correct sequence (in the UK) of RED, RED and AMBER, GREEN, AMBER, RED. THE HARDWARE We will need a red, orange (or yellow) and green LED; 3 220Ω resistors and your Arduino. THE CIRCUIT THE CODE The first thing that we…