{"id":7392,"date":"2020-10-18T15:18:42","date_gmt":"2020-10-18T19:18:42","guid":{"rendered":"https:\/\/dronebotworkshop.com\/?p=7392"},"modified":"2023-04-12T10:24:25","modified_gmt":"2023-04-12T14:24:25","slug":"ac-arduino","status":"publish","type":"post","link":"https:\/\/dronebotworkshop.com\/ac-arduino\/","title":{"rendered":"Controlling AC Devices with Arduino"},"content":{"rendered":"\n

\"Download \"Parts<\/a> \"View<\/a> \"Download<\/a><\/p>\n

The Arduino is a microcontroller, which means it\u2019s a small device made to control things. Today we will see how we can control AC devices with an Arduino.<\/p>\n

<\/div>\n

Since most of you will probably want to control devices that use line (mains) voltage we\u2019ll be paying particular attention to safety.<\/p>\n

Introduction<\/h2>\n

You can control a lot of things with an Arduino. Displays, LEDs, and other devices can easily be hooked up to the I\/O pins and controlled with a simple sketch.<\/p>\n

But the output ports on an Arduino, or any microcontroller, are only designed to control logic-level devices. Interfacing to anything that requires more than a logic-level signal is going to require external components.<\/p>\n

We have already seen how we can control DC operated devices<\/a> by using BJTs (Bipolar Junction Transistors) or MOSFETs. Using these components we can switch voltages and currents that would otherwise destroy our little microcontroller.<\/p>\n

\"Control<\/p>\n

Controlling AC devices requires different techniques. Semiconductors that can switch DC current can only pass part of the AC waveform, so they can\u2019t be directly used to switch alternating current.<\/p>\n

The \u201cdifferent techniques\u201d we can use to control AC range from semiconductors to electromechanical devices.<\/p>\n

But, before we look at any of the ways we can control AC with an Arduino we need to discuss a very important consideration – safety.<\/p>\n

Safety First!<\/h2>\n

While it is possible that you only intend to control low-voltage AC devices it is more likely that you\u2019d like to learn how to control the equipment plugged into the outlets in your home or office. After all, it\u2019s much more useful to switch on a desk lamp than it is to turn on an LED.<\/p>\n

But before you start planning how you’ll control your entire home with a few Arduino’s you need to consider the dangers involved in working with high-voltage AC power.<\/p>\n

Alternating Current 101<\/h3>\n

Alternating Current, or AC differs from Direct Current (DC) in that it constantly changes polarity, oscillating like a sine wave between positive and negative at a predetermined frequency.<\/p>\n

That frequency can vary depending upon where on the planet you are, in North America it is 60Hz while in most other parts of the world it is 50Hz. Some industrial applications use higher voltages and frequencies as high as 400Hz, but we won\u2019t be considering these in our experiments.<\/p>\n

Another thing that varies worldwide is the voltage level<\/a>, North American residents have voltages from 110 to 120 VAC delivered to their homes while many other countries use a higher 220 to 240 VAC.<\/p>\n

\"Danger<\/p>\n

Please note that despite using a lower voltage North American AC is just as dangerous, as it\u2019s the combination of voltage and current that needs to be considered. Also, North American homes actually do have 240 VAC delivered to them but it is split into two phases, each one carrying half the voltage. These \u201chalves\u201d are distributed around the home, and the full 240 VAC is made available for appliances like dryers and stoves.<\/p>\n

Coming into contact with such high voltages can be dangerous, in fact, it can be fatal!<\/p>\n

Here are a few guidelines for working with AC:<\/p>\n