Author Topic: build your own temp/hum sensor for vp2  (Read 31342 times)

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Offline jerryg

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Re: build your own temp/hum sensor for vp2
« Reply #50 on: April 02, 2012, 01:51:49 PM »
I got the shield in the other day and it was very easy to change out. All i had to do was remove the top plates of the shield to get to the fan and remove it so i could get the sensor board out and snap the temp/hum sensor on it, then i just slide the board back in place, routed the cable like it showed and reassembled it. It took about 10 minutes to do. I do not know why Davis doen not sell a retrofit. It would be even easier if it came with the sensor already installed. All you would have to do is mount it to the rain base with the shorter screws and pull out two plastic tabs to active the nicad batteries. You could keep the old sensor for a spare. It works just fine and i compared it to the daytime fars that i converted to 24 hr and the converted shield compares pretty close. I also compared the daytime fars and was not too impressed with the results. The fan starts running after the sun has been up a couple of hours because the sun has to hit the solar panel to get it running and does not have enough umph with just daylight showing. It stops running just before the sun goes down. You have to have the 24 hr solar panel to make the fars work right. The fan runs when daylight breaks. The fan only helps during the day when the wind it light. The 24 hr fars works good at night when the wind lays and you get a more consistant changing of humidity and temp. The daytime fars lags behind on that score as does my stevenson screen. They both catch up after some time and the temp and hum readings have slowed down later at night.

Offline jerryg

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Re: build your own temp/hum sensor for vp2
« Reply #51 on: April 24, 2012, 10:56:48 AM »
In case anyone wants to convert their shield to 24hr Archer Trading Post has two showing on his site for sale.

Offline jerryg

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Re: build your own temp/hum sensor for vp2
« Reply #52 on: June 24, 2013, 11:06:50 PM »
This is an update to my old topic. Sloweather posted in a new topic a couple days ago about getting the sht15 for 10 bucks which is alot cheaper than buying a new one. I ordered 5 sensors with 7 bucks postage and it took 4 days for them to show up in the mail box. I removed one from the flex strip and soldered connection wires to the sensor and then soldered my connection cable to the wires. I hooked it up to my spare iss and it worked fine except the temp was showing 1.2 degrees higher than my calibration thermometer. The only time i hooked up the sensors before was on the Davis or a breakout board that had the .1 ufd decoupling capacitor on board, so i got a ceramic cap and put across the vcc to ground and the temp came down to the correct value. The cap has to be connected for the sensor to be correct on temp. I have it outside in a shield and it is working just fine. So for ten bucks and a little work the sensor can be repaired with the better speced sht15. Thanks to Sloweather for the link. http://www.allelectronics.com/make-a-store/item/THS-15/TEMPERATURE/HUMIDITY-SENSOR-SMD-ON-RIBBON/1.html

Offline dendrite

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Re: build your own temp/hum sensor for vp2
« Reply #53 on: June 24, 2013, 11:43:18 PM »
So what is the final consensus? Does the VP2 use the SHT11 or SHT15? The VP2 specs I saw looked closer to the SHT15.

Offline jerryg

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Re: build your own temp/hum sensor for vp2
« Reply #54 on: June 25, 2013, 10:36:46 AM »
The vp2 uses the sht11 which has slightly poorer specs on the high and low end of humidiy performance.

Offline SLOweather

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Re: build your own temp/hum sensor for vp2
« Reply #55 on: June 25, 2013, 12:51:52 PM »
The chips are identical in footprint, appearance, and pinout. They are likely made on the same line at the same time, and sorted into 11s or 15s at testing.

Unsolder your SHT11, solder in the SHT15. That's what I do when I repair ISS sensor assemblies.

Offline jerryg

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Re: build your own temp/hum sensor for vp2
« Reply #56 on: June 25, 2013, 01:44:04 PM »
Hey SLOweather i am curious as to how you found these sensors for such a great price. They list them wrong as ths15 instead of sht15 so would not show up on a search. Was it real genius or just dumb luck  :lol: ?

Offline SLOweather

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Re: build your own temp/hum sensor for vp2
« Reply #57 on: June 25, 2013, 03:32:32 PM »
It's been a while, so I'm not quite sure. I get their paper catalog so I might have seen it there.

Hey SLOweather i am curious as to how you found these sensors for such a great price. They list them wrong as ths15 instead of sht15 so would not show up on a search. Was it real genius or just dumb luck  :lol: ?

Offline dendrite

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Re: build your own temp/hum sensor for vp2
« Reply #58 on: June 26, 2013, 09:21:55 PM »
The vp2 uses the sht11 which has slightly poorer specs on the high and low end of humidiy performance.
The VP2 temp sensor spec chart seems to correspond more with the SHT15 to me based on these charts...

VP2 (scroll to near the bottom)
http://www.davisnet.com/product_documents/weather/spec_sheets/6152_62_53_63_SS.pdf

SHTx
https://www.sparkfun.com/datasheets/Sensors/SHT1x_datasheet.pdf


Offline DeKay

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Re: build your own temp/hum sensor for vp2
« Reply #59 on: June 26, 2013, 10:24:58 PM »
The vp2 uses the sht11 which has slightly poorer specs on the high and low end of humidiy performance.
The VP2 temp sensor spec chart seems to correspond more with the SHT15 to me based on these charts...

VP2 (scroll to near the bottom)
http://www.davisnet.com/product_documents/weather/spec_sheets/6152_62_53_63_SS.pdf

SHTx
https://www.sparkfun.com/datasheets/Sensors/SHT1x_datasheet.pdf



It is an SHT11.  See here.

Offline C5250

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Re: build your own temp/hum sensor for vp2
« Reply #60 on: June 26, 2013, 10:37:55 PM »
It is an SHT11.  See here.

Without a doubt it is an SHT11. I don't think the specs have changed since the older analog sensors were being used...
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Offline dendrite

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Re: build your own temp/hum sensor for vp2
« Reply #61 on: July 15, 2013, 08:55:12 PM »
Would this work on a VP1?

Thanks!
  
Edit 2/5/2012
I think I answered my own question



This is the Vantage Pro 1 temp / humidity sensor (the the protective cover taken off), and it is defiantly not an SHT11

Any idea on what it actually is? If I could find that white sensor (marked Y421 on the plastic) I could easily swap it out when it dies. I have 5 of these things around Gloucester, MA (a lot of salt and wind) and it would be nice to fix it myself when they die.

Edit Later 2/5/12
Found out the white thing is the humidity sensor, and the blue thing is the temp sensor.  I pulled the white thing and the humidity read 100%, which also means if someone has a station reading 100% it could simply be a bad connection to the humidity sensor.
Interesting.

Just performed my annual maintenance on the ISS and it turns out my VP2 temp/hum sensor is this one also. This was sent to me from Davis after my previous sensor failed. If its for the VP1, it seems to be working just fine in my VP2. Now I have an SHT15 lying around waiting for a breakout to solder it to.

Offline jerryg

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Re: build your own temp/hum sensor for vp2
« Reply #62 on: July 15, 2013, 09:39:40 PM »
I am not familiar with the vp1 sensor but believe it is an analog set up. Looking at the picture it looks like there are two holes where a standard humidity sensor would go. It also looks like it has the traces for an sht chip with two holes for a .1 cap. It would be interesting to ohm out the traces and see if the leads go to the right pins on the plug, if so you could remove the temp sensor and solder the sht on the board.

Offline hwcorder

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Re: build your own temp/hum sensor for vp2
« Reply #63 on: July 20, 2013, 11:14:19 AM »
I bought an SHT75 to replace my aging sht11 temp/hum sensor in my VP2. Also bought some 4 socket connectors and the sf1 filter. Below are photos of my finished product. I glued the connector and wiring in place.  Once the glue set I soldered the connections very carefully as the pins are very fragile with very little clearance between them.  I then used silicone making sure to fully seal all connections to protect them from moisture.  The silicone also helps adhere everything the to plastic piece that slides into the FARS.  This way if I need to replace the sensor I can simply take the old one out and plug the new one in.  For the SF1 filter i carefully cut a small notch to accommodate the neck of the sensor. With the sensor in the filter I attached the filter to some backing make from an old temp/hum module pcb board.  I cut a hole in the backing (not shown) and covered that using a cutout of the old filter that came with the original Davis sensor. This was done to try to improve airflow. I just finished it this morning, plugged the new sensor in and it seems to be working beautifully.  I will post on sensor performance in a couple of days.

If I do another project like this I will find a way to make the potting (silicone) look better.  Perhaps using some electronic potting epoxy will be easier to work with. In a few months I will look things over to see how the silicone and connections are holding up to weathering. 



Offline jackman

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Re: build your own temp/hum sensor for vp2
« Reply #64 on: July 20, 2013, 12:56:46 PM »
Does anybody know if this sensor will work on an old Davis WeatherMonitor II?

Offline johnd

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Re: build your own temp/hum sensor for vp2
« Reply #65 on: July 20, 2013, 02:35:05 PM »
Does anybody know if this sensor will work on an old Davis WeatherMonitor II?

No it won't. WMII used the older type of 'analogue' T/H sensor.
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Offline kjbann

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Re: build your own temp/hum sensor for vp2
« Reply #66 on: July 31, 2013, 11:58:10 AM »
I'd sure like to have an SHT15 or SHT75 in my VP2. Much as I hate to wreck a new board, I was thinking of buying a Davis 7346.166 temp/hum sensor from Archer and replace the sensor. That board would go in the VP2 and the board that comes out of the VP2 would go in a wireless temp station to add hum sensing to that.

After reading posts above from hwcorder and jerryg, it seems that maybe the board could be built from scratch with the SHT75, a .1 ufd capacitor, possibly the SF1 filter cap which I understand would require modification and a cable with RJ? connector.

Is there more to the board than that, or would that work for a new board w/o the $89 cost of the Davis board as a foundation?

I realize it probably needs to mount to a small pc board for mounting in the FARS and potting & sealing concerns need to be addressed.

For right now I'm just wondering whether to order the board from Archer, or start a grocery list to build from scratch. I haven't physically seen the sensor board, and prefer to build the new board and then do the swap.

Thanks,
Ken

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Offline jerryg

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Re: build your own temp/hum sensor for vp2
« Reply #67 on: July 31, 2013, 04:54:36 PM »
The sht75 comes mounted on a board with the .1 on it and has four pins to plug into a socket. The filter will fit over the sensor but you do have to cut a little notch in it to fit right. I soldered my cable leads directly to the pins and sealed the connections with some electrical sealant and secured it in the shield with the black cable clamp which holds it just fine. I used the same sealant to secure the filter to the board. Has been working just fine.

Offline dendrite

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Re: build your own temp/hum sensor for vp2
« Reply #68 on: July 31, 2013, 11:52:55 PM »
Have any of you had any noticeable changes in readings since going from the SHT11 to the SHT15/75? Any side-by-side comparisons?

Offline kjbann

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Re: build your own temp/hum sensor for vp2
« Reply #69 on: August 01, 2013, 02:57:13 PM »
jerryg,
Thanks - that helps. I think I'll go ahead and order an SHT75 and the filter cap. I've been trying to find a socket to make future replacement 'plug and play' with a little dielectric grease. Haven't been successful so far. I'm mainly looking at Newark because they have the sensor in stock.
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Offline jerryg

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Re: build your own temp/hum sensor for vp2
« Reply #70 on: August 01, 2013, 05:52:11 PM »
Temperature wise they compare pretty good, we do not get extreme changes in temp down here in s.e. texas. Where i notice the real difference is the humidity on the low end is alot better. With the 11 when we had a cold front come through and drop the humidity down to 10 or 15 percent my 11 would run 4 to 5 percent higher and with the 15 it came within 1 to 2 percent. I just like having the better speced sensor because i can lol. I have compared the sensors in the same shield with 2 vp2s uplinking to wu and watching the consoles and other than the low end humidity readings they compare fairly well. Mostly i replaced them on 2 davis boards because they died and why not use the better one. I like to experiment with the weather gear, right now i am comparing the 24hr fars with my homemade pvc tubing shield and a modified dfars. I made some mods to the dfars and for the last week it has been working better than the 24hr fars as far as temp goes.

Offline jerryg

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Re: build your own temp/hum sensor for vp2
« Reply #71 on: August 02, 2014, 11:03:49 AM »
I thought i would do an update to this post with the latest info i have come up with. I have tried all kinds of mountings to make a diy sensor and have probably made 30 of them lol. My final and best solution for those who can solder and work with small parts, plus the sensors lower the lag time of the Davis sensors because it gets rid of the big board and filter that Davis uses.  I ordered 10 sht 11 sensors from a company in China off of ebay for 8 bucks each with free shipping. I also ordered 10 smd breakout boards for 50 cents each which are just a little larger than the sensor itself and i got the sf1 filter that fits the sht11 from Newark. I had alot of cable an rj connectors on hand plus salvaged .1 decoupling caps from old boards. The total cost of a sensor is about 11 dollars and when comparing my sensor to Davis the temp and humidity lag time is cut down alot. The boards and sensors arrived in about 3 weeks from order, not too bad. As far as mounting the sensors i just let the sensor hang loose in the middle of the 24 hr fars chamber, works fine. For the regular shield i soldered acouple of wires off of the unused solder holes and made a loop on the end so it could be screwed down on the mounting holes, worked fine. The main thing is i made 10 sensors for less than the best price of one Davis sensor.



Offline dendrite

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Re: build your own temp/hum sensor for vp2
« Reply #72 on: September 15, 2015, 10:23:49 PM »
Bumping this because it was my motivation to switch my temp/hum over to the SHT75...

I had the SHT75 lying around for almost a year. I finally got the time to solder a 4-pin connector to an old temp/hum cord I had lying around. I lathered it up with some silicone conformal coating and then plugged the SHT75 into the socket.

I didn't have a lot of daylight to play with, but I wanted to test it anyways. The end result is I'm beyond impressed. The response is miles ahead of my old Davis temp/hum sensor. I have a 9V-12V fan in my FARS and I'm getting a lot of movement on the readings...even at night. One thing I didn't expect was for the sensor to report all tenth temp values...even in degF. The Davis sensor I had installed was one of the older analog ones and it skipped some values...i.e. 66.9,67.1,67.3,67.4,67.6, etc. This one reports all missing values in between. Obviously that's not overly important considering the accuracy of the sensor, but it always annoyed me that some values were skipped. I'm not sure if the Davis SHT11 ones skip any or not.

The only thing I didn't have time for tonight was to install a SF1 filter. The more I thought about it, the more I wondered if I could bypass the sensor filter and instead purchase an equivalent filter to install at the opening of my FARS. The SF1 specs state that the filter material is PTFE with polyester scrim. Has anyone ever tried anything like that? I'd assume I have enough torque and CFMs on my fan at 12V to pull plenty of air through a filter at the bottom of my FARS.

Just curious what you all think,

Brian

Offline jerryg

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Re: build your own temp/hum sensor for vp2
« Reply #73 on: September 15, 2015, 11:02:26 PM »
I thought about doing the same thing but changed my mine. The reason being is i took the bug screen off of my fars because our humidity at night generally runs in the mid to upper nineties most of the time and my hum. readings took some time to drop in the am and i found that the screen was holding moisture, like the screen on a window does when the wind blows through it and the humidity is high it runs down the screen. I haven't had any bug problems with the screen off anyway. I figured if i did it it would be like having a wet cloth on the opening. I guess if you live in a low humidity place it might work out ok.

Offline WirelessR

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Re: build your own temp/hum sensor for vp2
« Reply #74 on: September 23, 2015, 11:35:59 AM »
Some reverse engineering:
This sensor, pre nov 2005, has the following malfunctions.
The HR sensor is bad.
Some trougholes are broken (corrosion)

Somebody know the capacitance from the sensor in good condition?

Last picture is a replacement board with TH sensor Sensirion SHT15.

Regards,
Ruud
« Last Edit: September 29, 2015, 05:10:17 AM by WirelessR »

 

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