About these schematics
These schematics were drawn from an Oregon Scientific WM918 weather station purchased Oct 1999 (USA version). Older or newer units may differ.
Useful and verified user modifications have been included.
The LCD display is not included in these drawings. Also some circuits terminating in the micro-controller IC have a question mark indicating the exact pin number could not be determined because of the epoxy package.
All components are labeled as they appear on the silk screen. Since the rear board lacks pin numbers for the ribbon cables the pins are labeled left to right. Layout shows this arrangement.
Component values or part numbers were read directly from the device or from the Radio Shack listing.
Values were omitted when they could not be confirmed.
Corrections and additions are welcome. Send to email@example.com Subject: WM918.
The original Circad format files are available from the above email address. They range in size from 10Kb to 85Kb except the drawings with inserted images, they are 1.1Mb each.
All the drawings were originally created in size A landscape (11" x 8.5") except Layout which is size A portrait and MPU which is size B (17" x 11").
These schematics were created using CIRCAD'98, a demo program from http://www.holophase.com.
The files are in GIF image format.