Integrated Wi-Fi Relay Boards can provide you with clutter-free remote control of a variety of devices. Find out more.
Over the past few years, I have been doing a variety of projects with packaged relay modules. Mostly I have been using some Sainsmart 8 and 4 channel modules under micro-control. These have performed well. But, I ran into RFI problems when using Arduino devices with USB control.
So, I switched to Wi-Fi (wireless) control with my NodeMCU. Since this ESP8266 device has limited I/O, PCF8574 I2C extenders are used to control 16 relays. I found this approach gets rid of most RFI but requires lots of wires lying around.
Recently, I discovered a number of integrated Wi-Fi relay boards available online. I selected a 16 channel board, shown above, from Krida Electronics in Latvia. It sells for around $50 or less. I found cheaper models, but this one seemed quite well designed and built. Among its features are wireless connectivity with an ESP8266, GPIO expansion with a 16bit MCP23017 chip and quality relays.
Everything runs off a 5V power supply at 2 amps. My board came pre-loaded with a web server. Also, it looks like I can extend the I2C bus for other uses.
My initial tests were pretty good. The web server let me connect to the board as an Access Point using a PC or phone and switch individual relays off an on, etc.
Programming Integrated Wi-Fi Relay Boards
Even though Krida provides firmware to get things running, the design lets your write and install your own control software. Since the ESP8266 is a very standard device, it should be pretty easy for me to customize and install new firmware. I plan to rebuild my two channel antenna switch using my new board to get rid of a lot of the discrete wiring.
You will find a variety of similar relay boards online, either as 1, 2, 4, 8 or 16 channel designs. Prices vary, but are low enough to take a chance. I chose a Latvia design as something different from China. Just make sure you know how the relays are controlled over I2C and you can easily modify your board to your exact needs.