http://www.jlcinternational.com/articles/humidity_sensor_elements_info.htm ----- Original Message ----- From: "Vasile Surducan" To: "Microcontroller discussion list - Public." Sent: Saturday, August 04, 2007 7:47 AM Subject: Re: [PIC] low cost to measure R/Humidity ? > On 8/4/07, cllow2020 wrote: >> Is there a low cost RH sensor measurement method for long distance? >> >> As far as I know, DEW sensor ( >> http://www.electronic-circuits-diagrams.com/sensorsimages/sensorsckt2.sh >> tml ) for logic on/off. But capacitive method is another liner >> measurement refer to Measure humidity and temperature on one TTL line >> http://www.edn.com/contents/images/83001di.pdf , my question is how long >> can the TTL signal line go ? 50m ? > > Transform the TTL into a differential signal (LVDS or 5V > differential), use a CAT5 twisted pair and you'll go more than 50m. > The problem is that solution is not very precisely one. If you accept > any RH error of more than 5% then it's ok. > >> >> Any input ? >> >> Regards >> cllow2020 >> >> No virus found in this outgoing message. >> Checked by AVG Free Edition. >> Version: 7.5.476 / Virus Database: 269.11.0/927 - Release Date: >> 7/30/2007 5:02 PM >> >> >> >> >> -- >> http://www.piclist.com PIC/SX FAQ & list archive >> View/change your membership options at >> http://mailman.mit.edu/mailman/listinfo/piclist >> >> > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist