[time-nuts] Temperature (environmental) sensors

Daniel Mendes dmendesf at gmail.com
Tue Jan 3 13:48:13 EST 2017

Yesterday hackaday had a link to a humidy sensor comparison:


Em 03/01/2017 16:03, Mark Sims escreveu:
> I did a LOT of testing environmental sensors when I built my ultrasonic anemometer weather station that is part of a rocket launch control system.  The best humidity sensor I found was the DHT21/SHT11/AM2301/SHT15.  They run around $3 and can also provide temperature to 0.1C res / 0.5C accuracy.  I tested lots of MUCH more expensive humidity sensors and that one agreed the best to my lab grade Vasilia.  That said,  all humidity sensors are rather sucky.
> For pressure the MS5611 sensor was, by far, the best.  It can measure the pressure change equivalent to less than a foot of altitude.   It can also provide a high-res temperature reading (of the sensor, not the environment).  It uses 24 bit A/D converters.  I use a 10 DOF IMU board from Ebay ($10) or you can get the sensor only on a board for around $7.
> The weather station board uses a ATMEGA32 to read all the sensors and outputs an RS-232 stream that looks like NMEA data.  It uses four $1 SR04 ultrasonic  sensors to measure wind velocity/direction/air temperature.  It also supports a UV intensity sensor.  It uses the magnetometer/accelerometers on the IMU board as a digital compass so you don't have to orient the anemometer to north.  I've used the board without the ultrasonics as an environmental sensor.
> I use sensor noise from the IMUs and Atmel ADCs to implement a true random number generator that feeds the crypto systems that protect the launch controllers from neer-do-wells.  The TRNG output passes all tests of randomness with flying colors.
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

More information about the time-nuts mailing list