Ambient temperature compensation for wind sensors (Rev. C vs Rev. P)

[Sriraj]

Hi,

A quick search in the forum or web didn't get me a satisfactory answer, so I'm asking here again. Also, novice alert!

I purchased a Rev. C sensor for measuring indoor air velocities (,of course). I've connected it to two boards. One is MKR1010 and the other is Wemos D1 mini using an ads1115 analog-to-digital converter. Because Wemos D1 mini has only one Analog pin. I have not yet calibrated it, but it appears to give better results via MKR1010, compared to Wemos D1 mini. May be esp8266 isn't a reliable board for this sensor.

I am planning to use this sensor for thermal comfort studies, where the indoor temperature keeps changing. It fluctuates in the range of 24-30 °C. Basically, the occupants in the space are free to change the indoor temperature, while the air velocity is kept constant. The acceptable indoor temperatures are measured for varying air velocities.

Could you please clarify a couple of things regarding its operation:

• If I calibrate the sensor for a zeroWindAdjustment at a particular room air temperature, does it produce reliable results in indoor conditions when the ambient temperature keeps fluctuating? Or does the sensor work correctly at the ambient temperature it is calibrated?

• Does Rev. P suits the purpose I sated above instead of Rev. C, as it says that it includes hardware compensation for ambient temperatures? Does "hardware compensation for ambient temperatures" mean that it can be used in ambient temperatures other than the ambient temperature it is calibrated for zeroWindAdjustment?

Thank you very much for your help.

Best,
Sriraj

[oz]

Sriraj,

At the present you are much better off with the Rev P which has a range of calibration and precision not found on the rev C
If you include a note in your order about needing "the best ambient correction" I will send you a custom unit with a couple of resistors changed. This eliminates almost all ambient variation. The changes will go into the next revision.

[Sriraj]

Hi Paul,

Thank you very much for your reply. Can I place this order, with the note, "the best ambient correction" via the JeeLabs Shop as well? How much time does it take to ship to Germany, approximately? Thank you.

Best,
Sriraj

[oz]

The JeeLabs shop does not have any modified Rev P. sensors. Working on next revision now that will have more empirically derived ambient correction. Basically trimmed offset resistors, plus some other things.

Shipping to Germany depends on method. You can get things there in 3 days but it’s expensive. UPS and FedEx have their own customs expediters that make things more deterministic.
I also like their tracking.

Paul

[oz]

Are you comfortable with a little smd rework? It just involves swapping one resistor and adding another I believe.
Send me email and I'll tell you how to mod the Rev P.