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[wxsig] Sensors, Part II

wn0x at earthlink.net wn0x at earthlink.net
Sun Mar 4 15:21:35 UTC 2007


I would recommend the humidity kit and I-Button RTC to start with.  This will give you accurate temperature and humidity and pretty much fill the T238+ display.  The RTC is very convenient.

It has been my experience that standard telephone wire (Lowes has a 250' roll for $25) works best, and I have tried almost everything else including CAT5.

I found the following site from Dallas Semi helpful for proper wiring:


The RJ12 standard uses 6 wires, the RJ11 uses 4.  Both will fit in the X1W and T238 jacks, although the X1W only uses 4 of the wires.  The connector is the same size.  Select the option on the X1W to select its supply voltage externally, not from the 1-wire bus.

I would recommend placing the DS1994 RTC in the same cabinet has your T238+ and use the header near the RJ11 jack to connect the device.

I placed my X1W on the north side of the house at eye level.  Makes it easy to check on and gets it slightly above the ground effect.   Plastic cabinet with holes for ventilation.  The fan is for high humidity situations (>80%) to prevent the sensor for saturating.  The T238+ currently does not have a provision for turning the fan on/off.

Add a rain gauge or BP sensor as you get time and money.  It seems that most stations have BP, so maybe the rain gauge would be a nice addition to your area.  BP also seems to be consistent over a pretty wide area so you can look at nearby stations for an approximation.

Hope this helps.

Rich - wn0x/ap006

-----Original Message-----
>From: Paul Beckmann-wa0rse <wa0rse at gmail.com>
>Sent: Mar 3, 2007 7:27 PM
>To: wxsig at lists.tapr.org
>Subject: [wxsig] Sensors, Part II
>I am new to the T238+ and have an AAS instrument kit coming. From
>reading the messages here and on some of the websites, I figured out
>1. the temperature sensor in the AAS runs hot in the sun
>2. some of the sensors AAS sells don't talk to the T238+
>3. The X1W-1 and -2 from TAPR are good ways to go for adding additional sensors
>4. iButton RTC is a good idea for portable use.
>5. Temp and humidity should be at about 5 ft in a shield enclosure,
>preferably with a fan ala the X1W-2.
>wo0w (Red) forwarded the CWOP guide to me for late-night reading.
>1. how do all of you using iButtons typically interface them with the
>1-wire system? Dallas has many "dongles" available.
>2. do any of you have block diagrams or pictures of your more
>fully-fleshed out wx stations using X1W-1 or -2 with the T238 or
>3. there seem to be many options for additional sensors (rain gauge,
>for example) in the X1W-2 but no mention of what works and how to
>mount one.
>Any help?
>--Paul, wa0rse
>Dakota Cty, MN
>wa0rse at gmail.com
>wxsig mailing list
>wxsig at lists.tapr.org

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