Better results with a 'cracked egg'?

[Bob Holmstrom]

I have two eggs with additional sensors (Ozone, VOC, and Dust). I had difficulty getting them to agree even after many attempts at software updates. One seemed to work well, the other seemed bad so I sent it back for 'repair'. It was returned with out a fan in the sensor module (because it is currently thought that the fan effects readings) - this started a series of experiments.

First I ran them for several days, one with fan, one without. The egg w/o fan ran at a significantly higher temperature - surprise?

I am concerned that an egg without a fan is operating in a static environment that does not reflect the air outside the egg. It seems to me that the AQE (if a fan cannot be used) might work better if it had a hole at the top so that it operated like the dust sensor - e.g. a thermally induced change of air in the egg cavity. Rather than cut a hole in the top of the egg at this point, I did the following. I put a rubber band around the equator of each egg. Then I folded a 3x5 card 4 times the long way (8 layers) and then 4 times is the opposite direction - I installed the 'wad' in the gap at the top between the egg halves. (details of spacer supplied in case someone else wants to duplicate it.) I call the egg described - 'cracked' - it is clearly a compromise until I decide to cut a hole or holes.

So, now my two eggs are as identical as I can make them (excluding wire routing, etc) and are now online. They are eggs 104509 and 106358. They are currently operating indoors but will be moved outside in a day or two. They currently seem to track much better (shape of curve) - work is still needed to get values to agree! NOTE: Xively display for longer periods is rather mystifying - what is their algorithm?

An added thought - if this helps, perhaps an extension would be to supplement the thermal chimney by a heat source controlled by the egg shield temperature sensor. e.g. thermal induced air flow and temperature control. Why would that not be an improvement?

I would be very interested to hear if anyone is operating more than one egg in close proximity and getting good agreement.

Bob

[jeanrobe...@yahoo.ca]

Hi

Very interesting ! But i can't imagine the 3x5 card so can you post a photo or send it to me at: jeanrobe...@yahoo.ca

Thanks

Jean-Robert