Introduction: Battery Low Power Sensor 433MHz Long Range Transmission

In this instructable I will show how to employ this ultra cheap 433mHz transmitter / receiver kit to send and receive short messages over max 100 meters in open air or from anywhere in a house (tested).

RF transmission is boosted by the use of a DC-DC converter to 12V, switched on by an Arduino only when necessary. The Arduino is asleep most of the time, so very low power is used in this setup.

Purpose: Receive wireless information from multiple battery operated low power sensor units (weather station, security etc.).

Step 1:

The idea is to use an Arduino Pro mini that is modified to operate at ultra low power with 2 AA batteries and use it to monitor and send sensor information at certain intervals. The transmitter module is powered up at these intervals using a step up voltage converter to max 12 volt, so the transmission distance will be maximal.

Another Arduino Pro mini can be used as base station to receive the messages and display them via Serial.print, forward them via internet, to a database on a Raspberry Pi, or whatever you can think of. In order to measure transmission distances I operated this one from batteries as well. The signal of the setup was received up to 100 meters in open air and passes several walls in my home.

There is another instructable with more detailed information on the kit components: "How to interface with RF transmitter and receiver" by mybotic

Step 2:

The images show the setup of the two circuits and the build up in real life for test purposes. The LCD display shows the messages sent by the transmitter: the number of cycles it has been operating, the Vcc voltage of the Arduino and the voltage provided to the transmitter.

The code for the transmitter and receiver include further information how to modify the Pro mini to low power, as well as links to the necessary libraries.

Components, search eBay:

- 2 x Arduino Pro mini (< 4 euro), Serial Converter CP2102 module for programming (< 1 euro)

- 433mHz transmitter / receiver kit (< 1 euro)

- MT3608 2V-24V DC-DC Step Up power supply module (< 1 euro)

- wire, a few resistors and a NPN transistor.