Final Soil Moisture Sensor Design

Tuesday, June 28, 2011 by darco
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I think this is the final re-design of the soil moisture sensor that I will be sending off to Gold Phoenix for panelization and a small production run.

sms-2011-06-27-full

sms-2011-06-27-zoom

Just seven parts: two capacitors, three resistors, one ATTiny25 and a circuit board. I switched over to largish surface-mount parts and an edge connector instead of a standard 3x2 header. This board will be able to temperature-compensate using the on-board temperature sensor on the ATTiny25. I've also increased the length of the sensor to nine inches. Here is the schematic:

sms-2011-06-27-sch

By my calculations I should get back around twenty to thirty boards. Should be more than enough to cover the front and back lawns and the garden. Now to just work out how to wire them all up...