Issue with HIH-3610-003

M

Mikel Beck

Guest
I've got a Honeywell HIH-3610-003 humidity sensor. I have a 5V voltage
regulator that feeds it. I measure the voltage right at the input for
the sensor, I get 4.97V. The output of the sensor is about 15-20%
lower than it should be.

In a room (darkened) with a relative humidity of around 65%, the
sensor reads 48-52%. I can read the output voltage from this sensor
with a meter, it's putting out around 2.1V.

Outdoors, with the sensor covered (to keep it in the dark), it has
been around 75% humidity. The sensor reads 58-64%.

Am I missing something obvious here? Any help would be appreciated.
 
THose sensors may not be all that accurate. A microprocessor could easily
compensate for any proportional kind of offset.
The light sensitivity is not all that extreme IMO... you will see a jump
if you point a flashlight at it or expose it to direct sunlight.
How much current are you drawing?



On 10 Jun 2004 19:11:06 -0700, Mikel Beck <mikel.beck@elite-computing.net>
wrote:

I've got a Honeywell HIH-3610-003 humidity sensor. I have a 5V voltage
regulator that feeds it. I measure the voltage right at the input for
the sensor, I get 4.97V. The output of the sensor is about 15-20%
lower than it should be.

In a room (darkened) with a relative humidity of around 65%, the
sensor reads 48-52%. I can read the output voltage from this sensor
with a meter, it's putting out around 2.1V.

Outdoors, with the sensor covered (to keep it in the dark), it has
been around 75% humidity. The sensor reads 58-64%.

Am I missing something obvious here? Any help would be appreciated.
Click to expand...


--
Using M2, Opera's revolutionary e-mail client: http://www.opera.com/m2/
 
Mikel Beck wrote:
I've got a Honeywell HIH-3610-003 humidity sensor. I have a 5V voltage
regulator that feeds it. I measure the voltage right at the input for
the sensor, I get 4.97V. The output of the sensor is about 15-20%
lower than it should be.

In a room (darkened) with a relative humidity of around 65%, the
sensor reads 48-52%. I can read the output voltage from this sensor
with a meter, it's putting out around 2.1V.

Outdoors, with the sensor covered (to keep it in the dark), it has
been around 75% humidity. The sensor reads 58-64%.

Am I missing something obvious here? Any help would be appreciated.
Click to expand...
Read the comment line on the data sheet:
http://catalog.sensing.honeywell.com/datasheet.asp?PN=HIH%2D3610%2D003&FAM=humiditymoisture
--
John Popelish
 
John Popelish <jpopelish@rica.net> wrote in message news:<40C9220D.5EF7DFAF@rica.net>...
Mikel Beck wrote:
(snip)
In a room (darkened)...
(snip)
Outdoors, with the sensor covered (to keep it in the dark),...
(snip)
Read the comment line on the data sheet:
http://catalog.sensing.honeywell.com/datasheet.asp?PN=HIH%2D3610%2D003&FAM=humiditymoisture
Click to expand...
Not one of my more helpful posts. Sorry.
I would not expect this device to give best accuracy unless in
complete darkness (not just darkened).

Relative humidity is extremely sensitive to temparature. The slight
rise caused by your having handled the parts a few minutes earlier or
the small rise caused by the heat from the voltage regulator or sun
shining on the light shield (or any other radient energy) can lower
the relative humidity reading.

--
John Popelish
 
THose sensors may not be all that accurate. A microprocessor could easily
compensate for any proportional kind of offset.
Click to expand...
According to the datasheet, this sensor should be accurate to +-2% RH.
I'm off by more than that.

Read the comment line on the data sheet:
http://catalog.sensing.honeywell.com/datasheet.asp?PN=HIH%2D3610%2D003&FAM=humiditymoisture
Click to expand...
Right, that's why I keep the sensor in the dark.

Any ideas as to what's going on?
 
Not one of my more helpful posts. Sorry.
Click to expand...
Quite alright.

I would not expect this device to give best accuracy unless in
complete darkness (not just darkened).
Click to expand...
Complete darkness? That's kind of bizarre. Who would make a sensor
that has to be kept in complete darkness to be accurate?

Relative humidity is extremely sensitive to temparature. The slight
rise caused by your having handled the parts a few minutes earlier or
the small rise caused by the heat from the voltage regulator or sun
shining on the light shield (or any other radient energy) can lower
the relative humidity reading.
Click to expand...
I'm going to bring the sensor into my garage after sundown, close up
all the doors. That's as close to complete darkness as I can get. I'll
see what it has to say in that environment.
 
Mikel Beck wrote:
Not one of my more helpful posts. Sorry.

Quite alright.

I would not expect this device to give best accuracy unless in
complete darkness (not just darkened).

Complete darkness? That's kind of bizarre. Who would make a sensor
that has to be kept in complete darkness to be accurate?
Click to expand...
All silicon is light sensitive, but most is encapsulated in black
epoxy. This device needs to have access to the air to sense
humidity. That also allows light in.

Relative humidity is extremely sensitive to temparature. The slight
rise caused by your having handled the parts a few minutes earlier or
the small rise caused by the heat from the voltage regulator or sun
shining on the light shield (or any other radient energy) can lower
the relative humidity reading.

I'm going to bring the sensor into my garage after sundown, close up
all the doors. That's as close to complete darkness as I can get. I'll
see what it has to say in that environment.
Click to expand...

--
John Popelish
 
Any suggestions for a humidity sensor that doesn't have to be kept in
complete darkness? Anybody have any experience with the Sensirion SHT
sensors?
 
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