Re: Soil moisture sensors

[nobody@xxxxxxxxxxxx (Dave Houston)]

I doubt the regulator is critical or even that it needs to be 3.3V although
a different voltage will change the curves. Look at the LP2950/2951 family.
Search on LP2950 at Mouser or Digikey.

Mouser 80-C340C475M5U is a 4.7µF multilayer ceramic capacitor. They are
pricey. I'd try non-polarized electrolytics (Mouser 140-NPRL50V4.7) but
there may be electrochemical reasons why they don't apply in this
environment/application - I really don't know.

"Keith Rathband" <notreal@xxxxxxxxxxx> wrote:

>I have some more questions about the interface circuit given,
>
>The circuit shows an LT1761 IES-33 3.3V regulator - this seems to obsolete
>with my suppliers, can anyone suggest an alternative.
>
>Also - the circuit shows two 4.7uF ceramic caps, to isolate the sensor from
>the circuit. I'm having difficulties finding suitable ceramic cap of this
>value - can anyone one suggest an alternative ?
>
>Thanks,
>
>Keith.
>"Keith Rathband" <notreal@xxxxxxxxxxx> wrote in message
>news:d8kacc$oo0$1@xxxxxxxxxxxxxxxxxxxxx
>> I'm trying to use a Watermark soil moisture sensor in the my home
>automation
>> project. I believe this sensor cannot be read as a standard resistive
>sensor
>> using a DC voltage across the sensor, the voltage across the sensor must
>be
>> A/C.
>>
>> Also, Irrometer who make the sensor don't seem to want to giveout details
>of
>> the sensor's response curve, and temperature correction details.
>>
>> So,
>>
>> Does anyone have, or know where i can get an interface circuit schematic
>> diagram for the Watermark sensor.
>>
>> Does anyone have, or know where i can get details of the response curve,
>and
>> temperature compensation details.
>>
>> Thanks in advance
>>
>> Keith.
>>
>>
>