Maker Pro
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current reading for soil moisture meter

Hi. I recently made a small mistake. I purchased one of those probe
type "Made in China" soil moisture testers. There was a gardening
workshop, and the UC Master Gardeners group recommended the use of
these meters to prevent over or under watering.

The meter had no reading, even in soaking wet soil. It also had no
reading in dry soil. The resistance, as measured by a DMM , across the
probe tip was infinite. The meter was opened and the probe
disconnected. The measurement of resistance across the D'Arsonval
movement meter was similarly infinite. There were solder blobs and
solder spray across the front of the meter, indicating a sloppy
assembly technique. Since the case was now damaged, and the package
was long since discarded, this meter could not be returned. It is
likely that the probably now moved-on Chinese manufacturer would not
accept it back anyway.

Since the probe part looked like a battery (dissimilar metals), a
current reading was taken on the aformentioned dry and saturated soils.
A reading of 6 microamps and 700 microamps were obtained,
respectively.

Does anyone know the calibrations of the meter, offhand? Are these
rmeasured values representative of the observed range?

If a decent range can be provided, the meter (without the movement) may
be salvageable.

Thanks,
Eric
 
Hi. I recently made a small mistake. I purchased one of those probe
type "Made in China" soil moisture testers. There was a gardening
workshop, and the UC Master Gardeners group recommended the use of
these meters to prevent over or under watering.

Made in rip-off land ;)
Read about the "Dell" transformer with extra metal weight for that robust
feeling. And missing ground, thermal protection etc.. ;)
Or the wlan adapter where the antenna is just a piece of plastic. Or the
FET's that don't manage even 1/4 of their rateing..
was long since discarded, this meter could not be returned. It is
likely that the probably now moved-on Chinese manufacturer would not
accept it back anyway.

You could tell the shop you want you money back. And you can prove that the
product was faulty.
Since the probe part looked like a battery (dissimilar metals), a
current reading was taken on the aformentioned dry and saturated soils.
A reading of 6 microamps and 700 microamps were obtained,
respectively.
Does anyone know the calibrations of the meter, offhand? Are these
rmeasured values representative of the observed range?

You can use "buffers", it's liquids with precise pH value. And the buffer will
not change pH unless you push them far with acid or alkaline.
Blood infact works in a similar way to keep pH balance. It might even work to
use that substance too. It's readily available, and got a documented pH :)
 
S

Spehro Pefhany

Jan 1, 1970
0
Hi. I recently made a small mistake. I purchased one of those probe
type "Made in China" soil moisture testers. There was a gardening
workshop, and the UC Master Gardeners group recommended the use of
these meters to prevent over or under watering.

Made in rip-off land ;)
Read about the "Dell" transformer with extra metal weight for that robust
feeling. And missing ground, thermal protection etc.. ;)
Or the wlan adapter where the antenna is just a piece of plastic. Or the
FET's that don't manage even 1/4 of their rateing..
was long since discarded, this meter could not be returned. It is
likely that the probably now moved-on Chinese manufacturer would not
accept it back anyway.

You could tell the shop you want you money back. And you can prove that the
product was faulty.
Since the probe part looked like a battery (dissimilar metals), a
current reading was taken on the aformentioned dry and saturated soils.
A reading of 6 microamps and 700 microamps were obtained,
respectively.
Does anyone know the calibrations of the meter, offhand? Are these
rmeasured values representative of the observed range?

You can use "buffers", it's liquids with precise pH value. And the buffer will
not change pH unless you push them far with acid or alkaline.
Blood infact works in a similar way to keep pH balance. It might even work to
use that substance too. It's readily available, and got a documented pH :)[/QUOTE]

What do you suggest should be the soil moisture calibration setting,
assuming the soil is saturated with the OP's blood?


Best regards,
Spehro Pefhany
 
R

Rich Grise

Jan 1, 1970
0
Made in rip-off land ;)
Read about the "Dell" transformer with extra metal weight for that robust
feeling. And missing ground, thermal protection etc.. ;)
Or the wlan adapter where the antenna is just a piece of plastic. Or the
FET's that don't manage even 1/4 of their rateing..


You could tell the shop you want you money back. And you can prove that the
product was faulty.



You can use "buffers", it's liquids with precise pH value. And the buffer will
not change pH unless you push them far with acid or alkaline.
Blood infact works in a similar way to keep pH balance. It might even work to
use that substance too. It's readily available, and got a documented pH :)

What do you suggest should be the soil moisture calibration setting,
assuming the soil is saturated with the OP's blood?
[/QUOTE]
"too wet?"

;-)
 
R

Rich Grise

Jan 1, 1970
0
On Mon, 12 Jun 2006 09:50:21 -0700, ericchang wrote:
[about dead plant soil moisture meter]
Since the probe part looked like a battery (dissimilar metals), a
current reading was taken on the aformentioned dry and saturated soils.
A reading of 6 microamps and 700 microamps were obtained,
respectively.

Does anyone know the calibrations of the meter, offhand? Are these
rmeasured values representative of the observed range?

Apparently so, yes. :)
If a decent range can be provided, the meter (without the movement) may
be salvageable.


Sure - calibrate it! Set up a small array of pots, and let one get bone
dry, and soak the dirt a different amount in each, until the one on the
other end is "too wet"; then use an ordinary microammeter and note the
current for each saturation level - then the one that feels "just right"
should be mid-scale. :)

I've also found that by just feeling the soil with your finger you can
usually tell if it's too dry or too wet.

Good Luck!
Rich
 
Does anyone know the calibrations of the meter, offhand? Are these
What do you suggest should be the soil moisture calibration setting,
assuming the soil is saturated with the OP's blood?

You proberbly only need a drop or two between plates, if you don't ought to
get to the pharmacy store. No murder needed :)
 
E

ehsjr

Jan 1, 1970
0
Spehro said:
Made in rip-off land ;)
Read about the "Dell" transformer with extra metal weight for that robust
feeling. And missing ground, thermal protection etc.. ;)
Or the wlan adapter where the antenna is just a piece of plastic. Or the
FET's that don't manage even 1/4 of their rateing..



You could tell the shop you want you money back. And you can prove that the
product was faulty.




You can use "buffers", it's liquids with precise pH value. And the buffer will
not change pH unless you push them far with acid or alkaline.
Blood infact works in a similar way to keep pH balance. It might even work to
use that substance too. It's readily available, and got a documented pH :)


What do you suggest should be the soil moisture calibration setting,
assuming the soil is saturated with the OP's blood?[/QUOTE]

I think the suggestion was that the soil be saturated with the
manufacturer's blood.
Ed
 
E

ehsjr

Jan 1, 1970
0
Hi. I recently made a small mistake. I purchased one of those probe
type "Made in China" soil moisture testers. There was a gardening
workshop, and the UC Master Gardeners group recommended the use of
these meters to prevent over or under watering.

The meter had no reading, even in soaking wet soil. It also had no
reading in dry soil. The resistance, as measured by a DMM , across the
probe tip was infinite. The meter was opened and the probe
disconnected. The measurement of resistance across the D'Arsonval
movement meter was similarly infinite. There were solder blobs and
solder spray across the front of the meter, indicating a sloppy
assembly technique. Since the case was now damaged, and the package
was long since discarded, this meter could not be returned. It is
likely that the probably now moved-on Chinese manufacturer would not
accept it back anyway.

Since the probe part looked like a battery (dissimilar metals), a
current reading was taken on the aformentioned dry and saturated soils.
A reading of 6 microamps and 700 microamps were obtained,
respectively.

Does anyone know the calibrations of the meter, offhand? Are these
rmeasured values representative of the observed range?

If a decent range can be provided, the meter (without the movement) may
be salvageable.

Thanks,
Eric

I have always assumed that these cheap pos soil
wetness indicators are just 0 to Fs - in your
case 0-1mA - movements with limiting so the
battery doesn't fry the meter.
Ed
 
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