[time-nuts] HP5065A environmental sensitivities

Attila Kinali attila at kinali.ch
Thu May 19 01:49:44 EDT 2016


On Thu, 19 May 2016 06:33:38 +0200
"Björn Gabrielsson" <bg at lysator.liu.se> wrote:


> What are time-nuts using for monitoring the environment?

The Sensirion SHT21 has become the gold standard silicon based
humidity sensor over the past years. Even though it's quite old
(IIRC close to 10 years) it has performance metrics that still
rival modern sensors. Its rather "large" package with the 1mm
pitch makes it one of the easier to solder sensors as well.
It's only drawback is its relatively large price of €6

As for barometric sensors, the ones by Measurment Specialities
are quite good. The MS5607-02BA03 for example does a resolution
of 2.4Pa with a long term stability of 100Pa/a.
There is also the MS5611-01BA03 which offers 1.2Pa resolution,
but also doubles the price and I am not so sure whether that
tiny bit more resolution is more than just noise.

A little advice: If you want to measure pressure with high precision,
you should think about temperature stabilizing the sensor.

The same is true for humidity, but does not work as well, as temperature
stabilization (aka heating) changes the relative humidity and thus
the measurement value depends quite a bit on how the air around the
sensor flows.

Also, provide good and low noise power to the sensors. These are
precision instruments with high resolution ADCs. To work properly
they need a clean power source.

> I have been playing a little with the Bosch BME280 - doing air pressure,
> temp and relative humidity in a small form factor. Easy to interface to
> Raspberry Pi or Arduino.

The only Bosch sensor i've ever used was a BMA250 acceleration sensor.
It worked reasonably well, but i've never evaluated it for precision
or accuracy. But at least it looks like Bosch does not exagerate
in their datasheets.


			Attila Kinali
-- 
Reading can seriously damage your ignorance.
		-- unknown


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