Warning: in this example, we’re dealing with mains voltage. Setting D3 therefore turns on the relay and turns on the lamp. 0000006990 00000 n To use them, you stack the boards on top of each other as shown in the following figure. The PT is normally wired for NO operation, but you can usually configure it for NC operation as well. The Switching Voltage tells you how many volts you can switch with this relay. For this particular project, I used the Adafruit Feather M0 WiFi, an Arduino compatible Wi-Fi enabled microcontroller, the Adalogger FeatherWing, a real-time clock add-on board for the Feather, and the Adafruit Power Relay FeatherWing. 0000106983 00000 n 0000001276 00000 n This enables you to see how the board works and even test out your project’s hardware before you’ve written any code. NC pin is connected to the COM pin by default, unless you send a signal from the Arduino to the relay module to break the connection. When working with relays, be sure that your relay is rated for both the voltage and current used in your project; you wouldn’t want to let the smoke out of a relay out of carelessness. The application calls the pushButton function to trigger the relay; the function turns on an indicator light, triggers the relay, waits a half a second, then turns the relay and the LED indicator off. A DT switch can also have a center Off position between the two circuit path options. If the relay’s on, it will switch off when the applied voltage falls below 0.3 Volts DC. You’ll connect your switched circuit to the blue terminals on the right side of the figure. https://github.com/johnwargo/Seeed-Studio-Relay-Board, https://github.com/johnwargo/pi-relay-controller-modmypi/blob/master/relay_lib_modmypi.py, Adafruit Perma-Proto Half-sized Breadboard, Dozens of projects in every issue covering Robots, Drones, 3D printing, craft and more, Tips and skill-building tutorials with inspiration from the leaders of the maker community. I don’t know how exactly this works internal to the relay. It has a control system and (also called input circuit or input contactor) and controlled system (also called output circuit or output cont actor). Not exactly. // You will also see the corresponding Red LED on the 4 Relay board // light up when the relay is on. The output voltage on this pin is what triggers the relay. The chance of damage to the module due to the wrong connection is considerable, so check the label of each pin and ensure the contacts are correct. They may also include a few jumper blocks like the one I’ve shown here. The pin arrangements of the relay modules may be different from one another. Use Relay Logic to control lights using relays in standard applications as well as 3-way switching application. xref 0000107009 00000 n Where you need relays is when you want to open/close an external circuit, or where your circuit needs to control higher voltages than your system can provide. 0000002680 00000 n The Relay module can be used to sense external On/Off conditions and to control a variety of external devices. On the switched circuit side of the module, you’ll see the three switched connection points marked with the diagram shown below (the labels NO, Common, and NC are mine). In Normally Closed (NC) mode the opposite is true (shown in Figure 2). To put it simply, it is an automatic switch to controlling a high-current circuit with a low-current signal. Coil End 2. The PT is basically a box containing a relay with its switched connection wired across one of the conductors in an AC power plug. %%EOF Relays come in several form factors. The Relay FeatherWing gave my project an easy to use relay module I could just slap onto the microcontroller and get to work. The figure shows the switched connection configuration for the relay at rest. The setRelay function gives the application a quick and easy way to turn the relay on or off. When you apply an appropriate voltage to the control circuit, the electromagnetic coil in the relay activates and pulls the switch closed, enabling current to flow through the switched circuit. As you can see from the figure, they’re labeled as follows: Let me give you some examples. It is frequently used in automatic control circuit. Instead of making you hunt around for all the parts of the code that trigger the relay, we set the relay output pin in this constant and any part of the application that wants to use it can merely reference the constant. He wrote the first book on BlackBerry development and has published 4 books on Apache Cordova (also known as Adobe PhoneGap). Seeed Studio Raspberry Pi Relay Board v1.0. The switched side of the module has the same NO/Common/NC connectors you saw in the single relay module, only there’s 4 sets of them here, one for each relay. No relay (as a component) has a “signal” pin on the coil side, just two pins (which then need additional circuitry for load and spikes regulation). It has a control system and (also called input circuit or input contactor) and controlled system (also called output circuit or output cont actor). For my garage door opener projects, I was merely using a relay to ‘push’ a button, so the relay merely switched a low voltage circuit. With the switch thrown one way, current flows through one of the circuit paths, with it thrown the other way, current flows through the other circuit path. In this project, we are going to control the relay module with ESP32. To use the module, copy the library to your project folder then add the following line to the start of your Python application: With that in place, you can turn the relay on using the following code: where int_value refers to the relay number (1 through 4). It’s possible that your relay module will have a few jumpers on it. The position of this jumper will dictate how you trigger the relay in your project’s code. // You can here them click as there state changes from off to on and on to // off. <]>> Relay is an electromechanical device that uses an electric current to open or close the contacts of a switch. Used to trigger (On/Off) the Relay, Normally one end is connected to 5V and the other end to ground. For one of my projects, I used the Adafruit Feather microcontroller; the feather is an Arduino compatible suite of microcontroller boards that all share a consistent form factor and input/output pin layout. endstream endobj 53 0 obj <>stream 0000002007 00000 n 0000005849 00000 n The Library implements a set of methods for working with a digital relay module. I used a relay in my microcontroller-controlled garage door opener because I needed my project to mimic pushing a physical button (the garage door button on the wall) which required switching capabilities, not the ability to send an output voltage from the board. • IN1 trailer 0000006773 00000 n 2 relay module has two relays. Figure 13 – Seeed Studio Raspberry Pi Relay Board v1.0. It is frequently used in automatic control circuit. You also have the option to opt-out of these cookies. For this particular project, I used a Adafruit Feather with a real-time clock (RTC) module to drive the PT relay, enabling me to switch control to a light fixture using logic coded in the Feather application. 0000006649 00000 n The relay can be controlled through Arduino in a very simple way, like controlling an LED. The 4 channel relay module has two different types of electrical contacts inside – normally open (NO) and normally closed (NC). To trigger the relay in your Feather application, you would use something like the following: In this example, what I’m showing is a constant definition (describing which analog output pin the relay is connected to) and a function called setRelay that triggers the relay. Wiring a Relay Module to the ESP8266 NodeMCU Board. Here to turn on the Relay with Arduino we just need to make that Arduino Pin High (A0 in our case) where Relay module is connected. The solution is called a PowerSwitch Tail, and an example project I created using one is shown in Figure 15. 0000106328 00000 n There you have it, a quick and easy way to connect a relay to your IoT projects. 0000001893 00000 n Instead of buying relays and wiring them up with transistors, diodes and resistors, many manufacturers produce relay module boards that include everything you need. To put it simply, it is an automatic switch to controlling a high-current circuit w… For Pi Zero mounting, the board offers 4 mounting holes, so with the right standoffs and screws, you can mount the PiOT board solidly on top of the Pi Zero. 0000011196 00000 n If you want a simple app you can use to play around with the board, check out my project on Github. The one you use will depend on whether you want the 5V signal to turn the switch on or turn the switch off. 2. Then we will have to connect the communication pins IN1, IN2, IN3, and IN4 to the Arduino data pins 7, 6, 5, and 4. which should make sense now after reading the previous paragraphs. GPIO Zero includes other output types you could use for this as well. From a coding standpoint, you’ve already seen the code you need to control the relay, it’s in the Adafruit Feather section shown earlier in the document.