emonTx Shield 

An open-hardware wireless energy monitoring Arduino compatible

(Duemilanove, Uno and Leonardo) shield.





  • Apparent Power, Real Power*, Power Factor* and AC RMS voltage readings*
  • 4 x CT Current Sensor input
  • AC 9V RMS voltage sensor input
  • 433/868Mhz RFM12B (HopeRF) wireless transceiver to transmit/receive data to other OpenEnergyMonitor and JeeNode modules
  • On-board DS18B20 digital temperature sensor (not included as standard)
  • Status LED
  • Compatible with Arduino Duemilanove, Uno and Leonardo
  • Compatible with OpenEnergyMonitor modules (emonGLCD, emonBase - NanodeRF etc.)

* with 9V AC adapter


Help support the project by buying the emonTx Shield from the OpenEnergyMonitor Shop


emonTx Shield Technical Documentation Wiki Page
(including build guide)



See emonTx Shield folder in emonTx GitHub Firmware Repo


We believe open source is a better way of doing things.

View and download the emonTx Shield Schematic, PCB Eagle CAD files and BOM on SolderPad

The hardware designs are released under the Creative Commons Attribution-ShareAlike 3.0 Unported License 

Arduino Compatible 

The emonTx Shield is fully compatible with the Arduino Uno, Duemilanove, and Leonardo

The software uses Arduino libraries and the Arduino IDE to upload sketches



Get help and share your creations on the OpenEnergyMonitor Community Forums