Repair of Honeywell HIH4000 Humditiy Sensor

[kolbep]

Hi All.
My customer has an irrigation controller for their Cucumber tunnels.
The humidity sensor has packed up.
It is a Honeywell HIH4000 Sensor
This sensor takes 5v andGround in, and gives out a voltage relative to the humidity.
But there is a problem where the sensor is continually outputting the Input voltage.

New ones are quite pricey, so I was wondering if there are any tips on how to correct it.

The Datasheet is here :
 http://sensing.honeywell.com/honeywell-sensing-hih4000%20series-product-sheet-009017-5-en.pdf

Thanks
Peter

[SeanB]

The sensor is a single sealed unit, so you probably want to get another one with voltage output, or one with I2C or frequency output, and use a microcontroller to give a voltage output for it. Will be a little bigger, but will do, and then you will have the ability to use more sensor types.

http://www.adafruit.com/category/66

Otherwise they are only $18 on eBay....

http://www.ebay.com/itm/1pc-Honeywell-HIH-4000-001-Relative-Humidity-Sensor-Hygrometer-Moisture-USA-/160747625438?pt=LH_DefaultDomain_0&hash=item256d4e1bde

Not affiliated to seller, and likely a drop shipper in any case from PRC, so order fast before China closes for the new year, and as SAPO is going on strike ( Fark, AGAIN) on Monday, you probably will want to arrange with them for shipping via courier, or use a reshipper who will do that. Likely will cost more than the part, so buy  a few.

[wraper]

How do you suppose to repair integrated circuit? You could ask if you can repair failed MOSFET or RAM IC with the same extent. Not that expensive BTW.

the RH sensor is a laser trimmed, thermoset polymer capacitive sensing element with on-chip integrated signal conditioning.

[kolbep]

I was thinking maybe there could be some magic trick,
like maybe baking at some temp for some time.

Oh well, Let me quote them on a new one.

Thnks

[wraper]

I was thinking maybe there could be some magic trick,
like maybe baking at some temp for some time.

Oh well, Let me quote them on a new one.

Thnks

In the cases when such a trick works, like if the bonding wire lost its contact, that usually helps only for a short time.

[dfmischler]

Look here.  Pick the one that matches your requirements (filter, or not?).  I bet the HIH-5030 series would drop right in to your circuit; check the datasheets.  Quantity one price is a bit over half of the price of a HIH-4030 part, and it will work over a wider supply voltage range.

[kolbep]

Look here.  Pick the one that matches your requirements (filter, or not?).  I bet the HIH-5030 series would drop right in to your circuit; check the datasheets.  Quantity one price is a bit over half of the price of a HIH-4030 part, and it will work over a wider supply voltage range.

Thanks for the tip. the HIH-5030 is a lot cheaper (can get 2 for the same price as the 4030). Let me check with the customer, and get their go-ahead.

BTW. this Aquarius Smart Control System is made in Cape Town, South Africa.
It consists of a Daylight Sensor module, that interprets the daylight shining on a white dome. (That goes Just outside the greenhouse tunnel)
It has another module that has the Humidity and Temperature Sensors, and that is inside the tunnel.
They communicate to the control module using an RS485 Signal. Both the Sensor Modules, and the Control Modules use Atmel uC.'s

It calculates the energy used by the plants based on the Light Exposure, Temperature, and Humidity. And then when it thinks it is time for a watering, it pulses a relay.
There is a Multizone Irrigation Controller that then picks up this pulse, starts the waterpump and Main Valve. It then Opens each tunnels solenoid valve for a preset period, to water each tunnel.


P

[dfmischler]

BTW. this Aquarius Smart Control System is made in Cape Town, South Africa.
It consists of a Daylight Sensor module, that interprets the daylight shining on a white dome. (That goes Just outside the greenhouse tunnel)
It has another module that has the Humidity and Temperature Sensors, and that is inside the tunnel.
They communicate to the control module using an RS485 Signal. Both the Sensor Modules, and the Control Modules use Atmel uC.'s

It calculates the energy used by the plants based on the Light Exposure, Temperature, and Humidity. And then when it thinks it is time for a watering, it pulses a relay.

How big are the tunnels?  What is the watering technique (e.g. drip irrigation)?  Air humidity is probably useful if you are trying to measure plant transpiration, but otherwise I am not so sure (many systems use soil moisture).  Don't you also need to know CO2 levels to measure transpiration?  What about plant growth stage and how that affects water transport from soil to the air?

[kolbep]

How big are the tunnels?  What is the watering technique (e.g. drip irrigation)?  Air humidity is probably useful if you are trying to measure plant transpiration, but otherwise I am not so sure (many systems use soil moisture).  Don't you also need to know CO2 levels to measure transpiration?  What about plant growth stage and how that affects water transport from soil to the air?

The Customer has 20 Tunnels,
Each is 30m(l)x8m(h)x4m(w).
I believe it is low pressure sprinkler heads that they are using.

I dont know much about Cucumber Farming. I was just called in to check the errors this control system was giving.