AC Powered 3 way Relay Node

Boards can be found at Dirtypcbc

Description

This is an ATmega328p-pu based board that has been created to enable wireless switching of 3 devices, it was designed for lighting needs, but pretty much any 110-240v AC powered device will work.

This device was designed to be installed in wall switch to be close to the existing switches, however you could use this outside of this application but either enclosure the device in a container that stops any access to the live power entering the board and even the screw terminals. Not safe to be around personal, especially children as there will also be no strain relief on the cables.

The module has been designed to work with EU/US Mains, so it has a Live and a Neutral input. The module itself is self-powered from the mains power input and is fused with a slow blow on the main input meaning any short on the board for any reason will cause the slow blow fuse to cut. Alongside of this, the relay channels are also protected with a 2-6A fuse themselves, meaning that any issues with the connected devices pulling any more than 2-6A will automatically cut out. Also available the option to attach 3 switches to the device to switch the attached devices on-board rather than using wireless switches or automatically switching the devices. This allows us to route a switch to the device just like a normal light switch would.

AC Safety Implementations

• 250VAC Varistor
• SB Fuse for PSU
• SB Fuse on Relays
• Creappage

Physical Dimensions

• Height: +/-25mm
• Width: 50mm
• Length: 50mm

Connectors

• 1 x 2pole 5mm Spacing Screw Terminal for AC Input
• 1 x 3pole 5mm Spacing Screw Terminal for AC output
• 1 x 4pin 2.54 Spacing FTDI Connector for switches
• 1 x 4pin 2.54 Spacing FTDI Connector for serial or reset button

Radio

nRF24L01 Radio Transceiver to communicate to MySensors gateway

Power Supply

This device is self-powered through an on-board transformer using the 120-240VAC Input to step down to 5V.

Software

Bootloader

MYSBootloader running at 8MHz Internal osc to enable the use of OTA updates.

FUSES

• low_fuses=0xF7
• high_fuses=0xDA
• extended_fuses=0x06

PROGRAMMING

You can use header1 to connect a serial programmer, pin 1 (from left) is the dtr pin so you will need a 0.1 cap in series before connected to serial programmer DTR pin, next is RX then TX and the last pin (first from right) is ground. Please note that you will need the board connected to mains power to be able to program it from serial.

Issues

The switches connector is a bit close to the HLK depending on the connector you are using it might be a tight fit.

Future version

• Add Vcc pin to programming header, so it could be program without mains
• Add Vcc to buttons header to be able to connect touch buttons
• Move buttons header to other side, by moving Radio down

Appreciations

This project was inspired by the "AC-DC double solid state relay module" project by Aproxx

Special thanks for the MySensors forum

Disclaimer

I do not advise you in any way to make/install this product into a property and therefore I take no responsibility for any issues, problems you have or even health implications that you endure while completing the installation or even using the product after installing. BUILD, USE and INSTALL ARE YOUR OWN RISK

Licensing

This product is licensed under the CC-BY-SA OpenHardware certificate. For more information please see https://creativecommons.org/licenses/by-sa/4.0/