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glynhudson committed Mar 14, 2017
1 parent f3847f3 commit 9cd3b06eadaf64f69d74f0c53a077641e6deaac7
Showing with 9 additions and 14 deletions.
  1. +5 −5 accuracy.md
  2. +3 −9 buildguide.md
  3. +1 −0 hardware/readme.md
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@@ -9,11 +9,11 @@ _The error below 40W could not be measured reliably and below 100W it was worse
It may be that your emontx will surpass or fail to achieve these accuracy levels depending on:
1) Calibration - as demonstrated in this test, it may be necessary to apply an additional calibration, the precision of the different components in the circuit means that the voltage calibration can be anywhere between 203.1 – 265.4 while the current sensor calibration can be anywhere between 109.44 – 112.78 see [CT and AC power adapter installation and calibration theory](https://openenergymonitor.org/emon/buildingblocks/ct-and-ac-power-adaptor-installation-and-calibration-theory)
1) Calibration - as demonstrated in this test, it may be necessary to apply an additional calibration, the precision of the different components in the circuit means that the voltage calibration can be anywhere between 203.1 265.4 while the current sensor calibration can be anywhere between 109.44 112.78see [CT and AC power adapter installation and calibration theory](https://learn.openenergymonitor.org/electricity-monitoring/ctac/calibration)
2) Bias position will have a large effect on accuracy at low powers see: [https://openenergymonitor.org/emon/buildingblocks/measurement-implications-of-adc-resolution-at-low-current-values](https://openenergymonitor.org/emon/buildingblocks/measurement-implications-of-adc-resolution-at-low-current-values)
2) Bias position will have a large effect on accuracy at low powers see: [https://learn.openenergymonitor.org/electricity-monitoring/ct-sensors/measurement-implications-of-adc-resolution-at-low-current-values](https://learn.openenergymonitor.org/electricity-monitoring/ct-sensors/measurement-implications-of-adc-resolution-at-low-current-values)
3) Level of electro-magnetic interference in your environment. Some laptops and switch mode power supplies can be a large source of electro-magnetic interference. Whether your circuit is shielded in any way i.e inside a metal box. A certain level of noise is actually a good thing as it helps overcome the limitations of trying to measure power where the current waveform is close to the ADC level magnitude, by causing the levels to flip higher and lower which after averaging gives a more accurate result.Â
3) Level of electro-magnetic interference in your environment. Some laptops and switch mode power supplies can be a large source of electro-magnetic interference. Whether your circuit is shielded in any way i.e inside a metal box. A certain level of noise is actually a good thing as it helps overcome the limitations of trying to measure power where the current waveform is close to the ADC level magnitude, by causing the levels to flip higher and lower which after averaging gives a more accurate result.
If you could also repeat this test and post up your results, it would be great to get some comparative data of different emontx's in real world use.
@@ -1833,11 +1833,11 @@ Applying the calibration:
### Plot of Maximum error at power
 ![](docs/emontxerrorplots01.png)
[](docs/emontxerrorplots01.png)
### Removing the first and largest error value so that we can better see the other datapoints:
![](docs/files/emontxerrorplots02.png)
![](docs/emontxerrorplots02.png)
## Update
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@@ -1,8 +1,6 @@
# emonTx V2 Build Guide
# emonTx V2.2 Build Guide
If you run into problems please post on the [forum](https://community.openenergymonitor.org).
If you run into problems please post on the [Community Forum](https://community.openenergymonitor.org).
The PCB is built in an orderly sequence starting with the resistors and small components that are low on the board, then working up to the bulkier parts like connectors. After soldering each component, you need to cut off the excess component leg from the bottom using some cutters.
@@ -233,17 +231,13 @@ See [DS18B20 temperature sensing](http://openenergymonitor.org/emon/buildingbloc
The ATmega328 chip is preloaded with the Arduino Optiboot 4.4 bootloader (select Uno in IDE) but no sketch. The correct sketch must be uploaded using the Arduno IDE.
emonTx Arduino firmware can be downloaded from: [https://github.com/openenergymonitor/emonTxFirmware.](https://github.com/openenergymonitor/emonTxFirmware)
The EmonTx v2 firmware examples are in the EmonTx v2 folder. There is a github readme that lists all the examples and the Arduino libraries required here:
[https://github.com/openenergymonitor/emonTxFirmware/tree/master/emonTxV2](https://github.com/openenergymonitor/emonTxFirmware/tree/master/emonTxV2)
**See Firmware folder in the root of this repo**
The best firmware for power monitoring with a CT sensor and an AC-AC Adapter for voltage measurement is the **emonTx_CT123_Voltage** example.
## Connections
See emonTx [Design Reference](http://openenergymonitor.org/emon/emontx/reference%20) page.
See PortMap in the Hardware folder in the root of this repo
## Testing
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@@ -28,6 +28,7 @@ The emonTx is one part of the OpenEnergyMonitor end-to-end web-based energy moni
![board.png](board.png)
- PCB: 63.3 mm x 56 mm
### Port Map

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