Can you please add the ability in WD to read the VAD value from a DS2438Z and calculate WHO UV Index based on a Calibration value in much the same was as MichaelT’s does except the Calibration value is constant.
I would like the ability to add the calibration value my self . i.e. WHO UV Index = VAD / Xcal.
E.g. WHO UV Index of 5 = 0.65V / 0.13
Voltage output of the Circuit I am using is Linea, and thus does not/should not require individual Calibration Values/ranges for the index. Calculation to 1 Decimal place should be OK.
I have a Circuit design that I will be looking to release to the WD Community (free of charge) which I have a prototype circuit of and it is proving both accurate and reliable. It can either be connected to a Hobby-boards Temp/Humidity/Solar board in-place of the Humidity sensor or could be constructed as a single UV 1-Wire board.
Derek - what sort of UV filter do you apply, and as the original CL140 is a broad band photo-diode which you can’t use for UV, what sensor device are you using instead for UV?
Interesting using the humidity sensor input into the DS2438Z chip for the new UV sensor.
I’m using that route form my e-Vane investigations too.
If that goes okay I was thinking of suggesting to Eric that if he ever re-models the board he adjusts the 3 humidity sensor ‘holes’ so that they match the pitch of a screw terminal block (I don’t think they do at present) - then he’d be able to offer another variant that was even useful to those of us who have little confidence or competence with a soldering iron[1]. :lol:
[1] I did (I think) manage to solder on a flying lead last weekend, but as I hadn’t use a soldering iron for many years it was quite fraught and took up all the available time. If there had been screw terminals I could just have gone straight to the connecting and testing stage.
Getting ready for work so only a quick reply. The UV Sensor is a UVB sensor and the board based on design information from the the manufacture of the UVB sensor. They even supplyed me with sample chips and I have a woking circuit. Nakid exposure to the sun of the UV SEnsor, it work well and appears to match the readings from the near by Hutt City UV Sensor. Now need to prove it in WD.
Good news and views both of you! Yes David, I cut off my old solar sensor - photodiode leaving short legs behind that I could solder to for an extension to locate the sensor elsewhere, it is buffered with a 390 ohm resistor across it so added lead length was hardly going to alter the circuit resistance. I was careful with the soldering to ensure electrical separation between the legs. I do need my glasses on for the detail work and something to hold the board each time…
Derek - that sounds perfect, yes so now its a matter of using that Honeywell humidity probe input for other purposes and an adjustment factor from WD.
David - Having a connector block there would also be useful I agree.
I’ve also used the HB temp/humidity/solar board minus the humidity and solar sensor for input from my ultrasonic snow depth sensor. The terminal option would be a GREAT idea. I’ve also had luck modifying the HVAC board for an analog input. The UV project sounds GREAT and I’ll be looking forward to the info.
Brian - just bumping this request. I have spoken with StokesValleyWeather and there is a good supply of a mini board and UV sensor (man’s thuimbnail size board) that can link to a solar sensor board in place of the Honeywell humidity sensor - which I don’t think many have unless it is part of their weather station. Or they can just get the bare humidity board kitset cheaply and not add the humidity device. It is a cheap option and I would like to get the appropriate hardware and get this working through the VAD input. We can then trial the devices and the build to get it working as a remote mounted diode in the correct position.
This would require a switch on the Dallas Humidity tab once the chip was recognised, and then a new coloured block made perhaps as the last tab page for all 1-wire devices - is there room?? I guess there is a UV program tab somewhere too that will need another setting as well.
I don’t think so, SVW has an import connection direct from Taiwan and I can share the links and images tonight. I think it is feasible to buy 10 - diodes separately and the mini opamp boards, and then give links to the 1-Wire Hobby-Board kits or humidity board for the individual to tailor to his needs. We don’t have prices for purchase yet - he was allowed a trial one free.
The basic system is more for internal industrial equipment production line testing, or embedded in solar beds, lamp systems, etc, so is geared for the dry installation, but the original LED package is avilable as well which would suit us better. Sorry Niko, I guess you’ll have to wait 24hrs to see the info - or this evening, I’ll post at 5:30 or so which will be about 10:30 CST… I think West coast is two hrs different…
Five at the moment, and I believe it will grow if the “hobby” type DIY makes it feasible - ie if some folks do it first… then others will follow. Probably just five or so initially at the start of the nighttime cloud sensor… but that was a simpler addon for many. How many are using the rain detection hardware and implemented through WD? Perhaps three? Two that I know of.
Anyway, if we can get the hardware sorted then, it would be easy for many.
At first glance I think the numbers were 100 min per order but am trying to see who else stocks their range of schottke diodes and op-amp circuit (which we could do ourselves anway) and then we could get the numbers down to 10 or so.
We are really hoping that Eric Vickery will follow it up with an integrated device and SVW has already spoken to him about it including a phone call I beieve and he is certainly aware of the interest. From work i have found the links I was referring to:
The original link I followed from Europe was here…
Quite horrific prices, but then found a manufacturer of some of them here:
Also an op-amp board to amplify the signal to a voltage AD input level for the 1-wire circuit.
SVW also received one of these voltage output units (thumbnail size…) and has tried to determine the circuit and make a similar circuit that is easy to DIY.
The curves on this product were basically following the erythemic curves (by the international Commission on Illumination (CIE) reference action spectrum for UV-induced erythema on the human skin(IS) 17166:1999/CIE007/E-1998). It is measure of the UV radiation that is relevant to and defined for a horizontal surface.)
Thanks, I’ll check those out. I bought some of the sglux diodes for about $30 each some years ago. They worked OK, easy to amplify the voltage to a useable level, but a) there is no calibration so you are on your own so far as calculating the UV index, and b) the viewing angle is much narrower than is really needed for this application.
Some were claiming 130degrees - the LED format i think, but that was only UVB range, still its a matter of finding a compromise and a package that suits. I believe the industrial ones for meterology use may be tracking devices anyway. Although on another site i saw a spherical probe from the Gen UV product range, possibly intended for exterior use.
About calibration, would it not be feasible to run next to a Davis or Oregon UV installation? We do a form of calibration for the mv for solar sensing, we do a comparison against other local barometers and isobaric maps… but for the integrated extra devices, they come already calibrated. So then, its a matter of comparing against a known device and then for some to compare day past readings against a local recorded value after the fact.
Also all PWS sites should have a waiver for use of data from the site, as very few PWS would be installed to correct standards and sitings, however we always strive for the best of what we have!
Here’s the measured response of mine compared to a cosine solar sensor. The Davis UV has a lens/diffuser, I’m guessing quarz glass but I don’t know. Sure if you have a Davis you could calibrate the home built one, but the sun elevation angle would affect the accuracy a lot and most people who are building one wouldn’t have that luxury. The whole health and safety liability issue does scare me some. Still an interesting project so long as the results aren’t taken too seriously.
I guess there is a UV program tab somewhere too that will need another setting as well.