Build an RF remote switch with a quad-channel relay to control up to four devices wirelessly.

Today we will build a 433MHz-based RF remote control switch with a four-channel relay to switch on or off up to four connected AC devices, such as a light, fan, electronic door, etc., wirelessly. The receiver module can be installed in any traditional or standard switchboard for controlling the devices.

Nowadays, you can purchase or build a DIY smart Wi-Fi switch and use them to control your AC devices over Wi-Fi. However, it’s not always possible to get a Wi-Fi signal in every corner of your premises. Moreover, they won’t work if the internet is down. In such cases, a 433MHz-based RF switch can be really helpful. The one we are going to build offers a decent range of 50-100 meters and works reliably well.

You can install and use this RF switch to toggle or control any light or AC load where wiring isn’t possible. By installing an RF switch, you can avoid any electrical work that might otherwise be required. For instance, we use it to open the garage door when we reach home, or the main electronic door using the transmitter module wirelessly when someone is at the door. You can build multiple transmitters to control the same receiver module when in range. We have one in our car and another at home.

To build an RF switch, you will need the following:

Refer to the following circuit diagrams to assemble and solder all the components for the transmitter and receiver modules. If you have never soldered before, here’s a guide to learning how to solder.

The transmitter circuit does not require many components. All you need is an HT12E encoder IC, a 433MHz RF transmitter module, a 1M resistor, and four push buttons.

For the receiver circuit, you need an HT12D decoder IC, two resistors, an RF receiver module, an LED, and the four-channel SPDT 5V relay module.

We are using the HT12E encoder IC on the transmitter circuit (Tx) and the HT12D for the receiver (Rx) circuit. Both are capable of encoding and decoding 12 bits of information that can consist of up to eight address bits and four data bits:

When a button is pressed on the Tx circuit, a low signal is applied to the transmitter. Based on the eight address bit pin connections with ground, HT12E encodes the data into a serial form, which is modulated and sent into the environment via the RF transmitter module.

When the data is received on the Rx circuit, it is sent to the Data Input pin (14). The information is then decoded, and a high signal is sent to one of the four data bit pins on the Rx circuit.

The data pin on the Rx circuit is connected to the relay module, which triggers when a high signal is received and turns on the connected AC load.

Besides switching a connected AC load on/off, you can also use this circuit to build many other projects. You can also pair this circuit with a NodeMCU or D1 Mini for long-range wireless data transmission and integrate it with a Home Assistant server for automation.

Below are a few examples where you can use this RF Tx and Rx circuit.

With an RF wireless transmitter and receiver switch, you can overcome the challenges and limitations of smart switches that require a Wi-Fi network to work. You can create multiple Rx circuits and control them with one Tx.

You may also change the address pin connection in Rx and Tx to use the different transmitters for different AC switches. Just make sure that the RF Tx and Rx circuits’ eight address bit pins are connected in the same order in both Rx and Tx to work. Changing the address pin connection on Tx will require changing the address pin connection on the Rx circuit. Otherwise, they won’t pair or work.

Ravi is an expert tech explainer, an IoT enthusiast and Linux lover with a background in big data and app development. He spends most of his weekends working with IoT devices and playing games on the Xbox. He is also a solo traveler who loves hiking and exploring new trails.