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Hygrometer

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beakie

beakie

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I bought **broken link removed** from eBay.

These are the details I have about the item.

Rated voltage 1V rms
Rated current 0.2mA
Operating frequency range 0.5 to 2kHz
Operating temperature range 0°C to +60°C
Operating humidity range 90% RH
Impedance range @ 60% RH 25°C 14.2 to 38.5kΩ
Humidity accuracy –5 to +5% RH
Hysteresis @ 40 to 80% RH 2% RH
Temperature dependence (ref.) 0.6% RH/°C

How should I plug it into an arduino?

Thanks
 
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What you have sounds like something from this type family of sensors. Not really a good choice of sensor for use with a PIC and actually a pretty low end sensor as to accuracy. There is a little more information located here. Personally I don't see it as a good choice as there are many good temperature compensated 3 wire devices out there that are inexpensive. Anyway, the links may help.

Ron
 
This is a capacitive type sensor and needs to be part of a circuit. Like an RC circuit. You thern need a table to determine the values outputted. I use the HIH-5031 sensor. Bit more expensive but work straight on ADC.
 
Hi guys, if my additional advice is relevant, I'd like to chip in:

I don't really understand how a two-pin component gives out a frequency output?
Actually capacitive humidity sensors works pretty good if you couple it with a 555 timer in monostable mode. then you'd get a humidity versus frequency output. An output of 50Hz-2kHz is pretty easy to achieve, and it is trivial for a PIC in Timer0/Timer1 mode to read such frequencies. I've used Honeywell's, they work good.

Not unless I'm missing some important details here. :eek:
 
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I intended to have four separate inputs using this schematic. But this component will obviously not work. Anyone got anything that is suitable for the above?

Thanks
 
beakie said:
I intended to have four separate inputs using this schematic. But this component will obviously not work. Anyone got anything that is suitable for the above?

Thanks
Click to expand...

Basically something that works like an LDR...

**broken link removed**
 
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You may want to give this link a read as to the HIH 4000 series of Honeywell sensors available from Mouser here. The HIH-4000-003 or HIH-4000-004 would do what you seem to be looking for. You don't mention a desired accuracy?

Anyway, the merit to the ones mentioned is they include a calibration data sheet.

Calculated values at 5 V
VOUT at 0% RH 0.826 V
VOUT at 75.3% RH 3.198 V

That gives you a slope of about 31.483 mV/%RH with a zero offset of 0.826 V.

If you want any accuracy and want to understand the calibration of RH you may want to read a little on saturated salt solutions.

Ron
 
Most welcome and let us know how it goes.

Ron
 
Beakie I also got a similar humidity sensor from ebay. To be blunt, it's a piece of crap! Not very accurate to say the least.

The one I got was a DHT-11 Temperature and Humidity Sensor. Of course the seller offered no datasheet. It was difficult to interface, but I made it work with an avr. The temperature measurements were okay, but the humidity measurements were not accurate at all.
 
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