Capacitave Humidity Sensor
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Hi All,
I have a Rotronics Capacitive humidity sensor I need to be able to read for
a stamp application. The range on the sensor goes from 200pF to 300pF. I
tried to set up an RC circuit to do so, but soon realized this was nearly
impossible. The ideal resistance is 300Mohms!!! Since this isn't feasible, I
used 30Mohms to test with. The times were all over the place, unusable. Does
anyone know of adifferent way to get th capacitance, preferably without
changing the hardware much, since I have boards burned [noparse];)[/noparse] Thanx
Nick
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I have a Rotronics Capacitive humidity sensor I need to be able to read for
a stamp application. The range on the sensor goes from 200pF to 300pF. I
tried to set up an RC circuit to do so, but soon realized this was nearly
impossible. The ideal resistance is 300Mohms!!! Since this isn't feasible, I
used 30Mohms to test with. The times were all over the place, unusable. Does
anyone know of adifferent way to get th capacitance, preferably without
changing the hardware much, since I have boards burned [noparse];)[/noparse] Thanx
Nick
_________________________________________________________
Do You Yahoo!?
Get your free @yahoo.com address at http://mail.yahoo.com
Comments
lightclb@y... writes:
> I have a Rotronics Capacitive humidity sensor I need to be able to read for
> a stamp application. The range on the sensor goes from 200pF to 300pF. I
> tried to set up an RC circuit to do so, but soon realized this was nearly
> impossible. The ideal resistance is 300Mohms!!! Since this isn't feasible, I
> used 30Mohms to test with. The times were all over the place, unusable. Does
> anyone know of adifferent way to get th capacitance, preferably without
>
Try inserting it into an oscillator circuit and reading oscillator the output
using PULSIN.
-- Jon Williams
-- Parallax
[noparse][[/noparse]Non-text portions of this message have been removed]
>Hi All,
>I have a Rotronics Capacitive humidity sensor I need to be able to read for
>a stamp application. The range on the sensor goes from 200pF to 300pF. I
>tried to set up an RC circuit to do so, but soon realized this was nearly
>impossible. The ideal resistance is 300Mohms!!! Since this isn't feasible, I
>used 30Mohms to test with. The times were all over the place, unusable. Does
>anyone know of adifferent way to get th capacitance, preferably without
>changing the hardware much, since I have boards burned [noparse];)[/noparse] Thanx
>Nick
Don't ask me for circuit or interface details, but some commercial polymer
(capacitance) humidity sensors I have, with readout (meaning they were a
turnkey solution), use a LTC-1043CS interface chip.
See http://www.linear.com/pdf/lt1043cs.pdf for a 2-page PDF data
sheet. Hope it helps.
Jim H
Paul
> Hi All,
> I have a Rotronics Capacitive humidity sensor I need to be able to read for
> a stamp application. The range on the sensor goes from 200pF to 300pF. I
> tried to set up an RC circuit to do so, but soon realized this was nearly
> impossible. The ideal resistance is 300Mohms!!! Since this isn't feasible, I
> used 30Mohms to test with. The times were all over the place, unusable. Does
> anyone know of adifferent way to get th capacitance, preferably without
> changing the hardware much, since I have boards burned [noparse];)[/noparse] Thanx
> Nick
>
>
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