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emonTx Arduino Shield SMT

  • emonTx Shield SMT V2.5 - SMT assembled - thru-hole components supplied as kit, soldering required
  • emonTx Shield with RFM69CW
  • emonTx Shield SMT V2.5 assembled - font
  • emonTx Shield SMT V2.5 assembled - rear
  • emonTx Shield SMT V2.5 assembled with 1 CT connected (CT sensor not included)
  • emonTx Shield SMT V2.5 on Nanode RF (not included)
  • emonTx Shield SMT V2.5 on Arduino Leonardo (not included)
  • emonTx Shield SMT V2.5 (green prototype) with DS18B20 temperature sensor
  • emonTx Shield SMT V2.5 Schematic
£16.56 (inc VAT) £13.80 (exc VAT)
40.00 Grams
Calculated at checkout

The emonTx Shield is an open source hardware arduino shield footprint compatible electricity and temperature monitoring shield that can be connected to any standard Arduino UNO, Leonardo, NanodeRF (for web connectivity and posting to emoncms.org) or even the new Arduino Yun.


The emonTx Shield was designed in North Wales by Trystan Lea and Glyn Hudson and is manufactured in the UK.



  • emonTx Shield assembled PCB (all SMT parts) 
  • Thru-hole component kit


Does Not Include

  • Power supply, cables, AC or CT sensors.



  • Apparent Power, Real Power*, Power Factor* and AC RMS voltage readings*
  • 4x current sensing inputs
  • 1x AC-AC 9v Adapter input for AC voltage measurement and realpower calculation
  • 1x on board DS18B20 temperature sensor footprint
  • 2x DS18B20 terminals available via terminal block.
  • 433/868Mhz RFM69CW (HopeRF) wireless transceiver to transmit/receive data to other OpenEnergyMonitor and JeeNode modules
  • Status LED


* with 9V AC adapter


Assembly of Non-SMT components

The board comes with all the SMT components the resistors, capacitors and LED already on the board. The non-smt components (the arduino headers, ftdi connector, CT and ACAC jack sockets) do not come pre-assembled and so a little soldering is still needed to complete the build of this board.

When assembling: The 3.5mm CT sockets and 2.1mm AC-AC Adapter socket needs to be soldered on the bottom of the PCB. This slightly unconventional design was chosen to make a low profile design possible.

See Technical Wiki page for info on RFM12B jumper settings, wiki page refers to the old 'thru-hole' design but the RFM12B operation and pin-out's have not changed.


EmonTx Arduino shield is not compatible with other Arduino shields that use I2C


Open Hardware

The emontx shield is open hardware with the designs released under the Creative Commons Attribution-ShareAlike 3.0 Unported License. The schematics and board files can be viewed and downloaded from the openenergymonitor github hardware repository here:


Firmware Examples

EmonTx Shield example code can be found on github here:


Full Documentation



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