Readings off


I have two emonTHs running, one with an optical sensor for reading electricity led pulses and the other which reads a reed sensor for gas.

I’ve left both running for an extended period of time and I have had to periodically adjust them both however given that I have had to do this I am concerned about the historic data and wanting to fix this so that this doesn’t happen again.

For both monitors I have created virtual feeds which should represent the meter’s current display, it is the offset that I have had to to keep adjusting to bring the live figure back into line.

How best can I go about identifying and rectifying the cause? I believe the gas meter reading with the reed sensor is due to switch bounce but I’m not sure what would be causing the electric meter reading.

The meters I have are as follows:

  • Llandis+Gyr E110
  • Estler BK-G4M

Below I have attached how I calculate the inputs/outputs. Any advice would be greatly appreciated as I’m currently being over charged by £60 by my current electricity supplier due to a mistake made by the meter reading person so would like to not have any future concerns about the readings reported by Emoncms.

Pulse input calculation:

Virtual reading:

Pulse input calculation::

Virtual reading:

Thanks in advance.

I had a magnetic reed switch connected to an emonTH for my gas meter, that counted approximately 2.5 per pulse. The addition of a 0.1 µF capacitor across the reed switch completely eliminated the problem. I suggested adding a note about this to the Wiki in January - it’s not happened.

I also have an optical pulse sensor, but that’s connected to an emonPi; so not directly relevant. That has on occasions picked up a nearby fluorescent lamp (with a thermal starter) being switched on or off. Others have found light getting to the sensor has been counted (perhaps obvious in hindsight).

Sorry about that, Robert. I can add that note for you.

Yes please, I think it would be helpful.

Robert, when you say across you mean like this?


Something like that - you haven’t drawn a capacitor. :laughing: It should look like this:


Robert, thanks for the suggestion of using a capacitor, it worked!