Hi Shyam,

I'm afraid $150 is not what I'd call low price for this type of sensor...

Okay it works out at $30 each but how can you say that it is cheap??

Have they some amazing specifications?

John.

Package of 5 sensors comes from www.humirel.com for US$75 + shipping and then I reship it to the students. They can also get from Humirel.

Humirel usually sends 5% accurate sensors and I get specially made with 2% accuracy for easy interchangeability. sensors from me becomes a better choice. These sensors are good and work fine for about 20 years and rarely get damaged. They were developed by Motorola and then became Humirel production line.

I teach and provide some hardware and software also if asked for help. Students can't go for PCB fabrication work so they take my help to get these as gifts. I can't say no to students once they get these sensors. They often keep talking for about six months and ask for few things (Can I help them with this and that, so I do send them all they ask for and never again ask for any money).

Do you think I am asking too much? I can perhaps reduce it to US$120 including shipping by airmail If that can help. I am not the sensor manufacturer so can't send for free.

Other sources for humidity sensors are Maxim-Dallas www.maxim-ic.com (1-wire sensors), Honeywell (resistive sensors), Sensirion http://www.sensirion.com/ (free sensor is available here and these are digital with ADC - I2C or serial communication). There may be few more sources and I have used them all. Best choice for free evaluation is Sensirion. I think there are few companies in China also for capacitive sensors.

Hi Shyam

Nice to see your helping nature for students.I am a student studying in NIT calicut.
One thing that puzzle me is the Technology by which companies manufacture these capacitive sensor.Even though my mini project is related to designing a interface for Humirel HS1101 sensor i am very much interested in knowing the technology and the Manufacturing process involved in making such sensor.If you can provide some insight or some document regarding this then i will be highly obliged to you.

Look forward to your reply

Regards

Abhishek Singh

abhisheks.nitc@gmail.com

Most of the polymers that are porous absorb moisture and some have capability to form an equilibrium at room temperature. Only such polymers are useful. Other way to make sensor is using human hair and its changing size with moisture, salts such as KCl in thin film form absorbing moisture.

I have one instrument that is meant for learning sensor interfaces, which your institute can purchase. Use my email on website.

Dear John,

This thread was started way back. Here is the final story of it.

I did make the sensors available for US$20 in India and few thousands of these sensors were tried by various people in the last 6 years. Few people took these for their manufacturing and price was dropped to them to 50% or even below depending on the volume of their usage.

Hydroponic green houses must have consumed much more of these sensors but in India we still do not have enough green houses yet.

My idea was to help students and engineers who wanted to try these for quick learning. People from outside India asked about 3000 sensors in all in this period.

It has been a good experience for me for this particular sensor.

Shyam

Hi precision, Where i buy SHT75 digital humidity and temperature sensor in india ?

You can now get HST75 for US$10 and HS1101 for US$5 each with minimum order for 10 numbers plus shipping cost. You get get these from me in small quantity.

Sir i have HS 1101,,i want to make a circuit which shows RH on LCD using 8051 MC,,but i find it difficult to design..can u please help me.

Ayaz