Tuesday, 12 January 2016

Remote Mains Switch with >100m range

I wanted the capability to switch a flood light fitted outside the garage from the Raspberry Pi. With the Raspberry Pi connected to the internet this would give me the ability to remotely switch this light on from anywhere in the world. I had a look at wi-fi enabled power sockets but none of them had the range I was looking for. This project shows how to use the Dual Remote Relay Tx & Rx to do this as this has a range well in excess of 100 metres.

It was simple enough to control the Remote Dual Relay Tx from the Raspberry Pi. The instructions for this is simplicity itself.

Dual Remote Relay 433MHz transmitter

To switch Relay 1 ON, apply 5V to the RL1 input and take the CLK input from low to high (at least 0.2 s) to low. To switch it OFF apply 0V to the RL1 input and take the CLK input from low to high to low.

The main part of the project was packaging the Dual Remote Relay Rx into an enclosure along with a mains socket and IEC socket so that we had a portable safe box that could be easily transported. Here is the finished product.
The IEC socket was mounted at the back.
The Dual Remote Relay Rx was mounted in the base of the enclosure. I marked off the 4 holes and drilled this out using M3 bolts and nylon pillars.The board needs a 5V supply. A Vigortronix (VTX-214-001-105) AC-DC power supply was used for this. We mounted this on a small piece of Veroboard and then used plenty of hot melt glue to insulate the tracks and hold this in place as shown below.

The image below shows the wiring between the IEC socket, the Vigortronix 5V supply and the mains socket. The Earth and Neutral wires go from the IEC socket to the Mains socket. The Live and Neutral wires go to the Vigortronix input. 

The Live wire from the IEC socket goes through the Relay connector back to the mains socket as shown below.

Various Safety Precautions:
* The IEC lead has to be fitted with a 3A or 5A fuse to protect the Relay and PCB uder fault conditions.
* All the wires are heat shrinked to prevent accidental contact
* Wires to the Veroboard are held on with hot melt glue for additional mechanical strength and to prevent accidental touching.
*  The antennae is kept inside the enclosure 
*  The user should not be able to touch any part of the elctronics

There is a second relay on this board - I plan to connect a mains powered klaxon to this. Would love to turn this on remotely to scare any neighbourhood cats if they wander around to poo in our garden.

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