Introduction

The 1-Wire® outdoor humidity and temperature sensor kit was designed to be used with the TAPR T-238 APRS Weather Station or N4XI's Linux based WXN weather server over APRS. It should work with any other 1-Wire® based software as the design is based on the original Dallas Semiconductor 1-Wire® Weather station. The humidity sensor with the kit is an improved version over the original part. It has proven stable with good accuracy over a wide range of temperatures and conditions.

The design is flexible in that power for the sensors can be taken directly off the 1-Wire® bus or from an external power source (as is the case with the T-238 Weather Station or the X1W-1 Inside Sensor/Interface board).

The board also features an aspirator (fan) to improve humidity readings. The fan employed uses ball-bearings which should give a longer life-span than sleeve bearings. Provisions for an extra temperature sensor is also provided to allow experimentation with measuring relative humidity using the wet/dry bulb method. This is purely an experiementer's option as there is no software to support this method of measuring relative humdity at the present.

The humidity sensor must be protected from strong light and direct exposure to the elements. The mounting centers for the sensor board match up to the Davis Instruments Passive Radiation Shield, #7714. The shield works well. If you do not wish to use the Davis shield, some type of enclosure must be fashioned to house the board and protect the humidity sensor. The X1W-2 kit does not come with an enclosure.

Latest changes and other information on the X1W-2 is available at either of the following two sites:

http://www.tapr.org/
http://home.insightbb.com/~n4xi

The T-238, X1W-1 and X1W-2 are discussed on the Weather Special Interest Group (WXSIG). You can join WXSIG via the web at:

https://www.tapr.org/mailman/listinfo/wxsig

What's In A Name?

Why X1W-2? The conceptual designer is N4XI. The X comes from the first letter in the suffix of the call. 1W is for 1-Wire® and the -2 represents the second kit in the 1-Wire® kit series.

Acknowledgments

The Tucson Amateur Packet Radio X1W-2 Kit was made possible by the efforts of:

John Bennett, N4XI – Conceptual and PCB Design
Steve Bible, N7HPR – Project Manager
John Koester, W9DDD – Assistant Project Manager
Joe Borovetz, WA5VMS – Parts Liaison
 
Dwight Hazen, WB9TLH – Beta Tester

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