USB temperature and humidity sensor

[MikeWilson]

Good afternoon,

I know a few members are using USB temperature and humidity sensors to track the temperature and humidity (of course!) in their observatories. Which make/model do you recommend - are they reliable and where can one purchase them from?

Is it possible to run more than one from the same machine?

Thanks in advance :-)

Mike

[Psychobilly]

I used to use the standalone USB pen type ones made by Lascar... Just to keep an eye on the Environmental conditions in the obs and check the dehumidifier was controlling the humidity properly

http://www.rapidonline.com/SearchResults.aspx?kw=lascar

Peter...

[Gtech]

I picked up the TemperHum usb stick off ebay (via Hong Kong) for £14. Very nicely made, although it does need first time calibrating against a reliable temp/humidity source.  Fortunately I live close to a weather station, so I call up there web page and do the offsets.

The Temperhum includes a PC app for logging and also works with BYE, so you can tag your image filenames with weather data, good for building libararies of darks etc. Highly recommended.

[teleskopjo]

I use Lascar EL-USB-2 (no digital display) and find they work great!

[FraserClarke]

I use the one-wire system with a USB interface. I got mine from here;

http://www.sheepwalkelectronics.co.uk/

Though there are other suppliers. I see he is now doing other modules beyond temp/humidity.

I've been really impressed with the one-wire stuff -- I don't think I've had a single failure/glitch in 3 years of continuous operation...

[Joguj]

http://www.netatmo.com/en-US/site

I bought one of these recently. Few more pennies but quality equipment. It takes indoor + outdoor readings every 5 mins and uploads to the netatmo server so you can check your sensors from anywhere. You can also download historic data in csv format. Nice android/ios apps also.

[Gina]

I use the one-wire system with a USB interface. I got mine from here;

http://www.sheepwalkelectronics.co.uk/

Though there are other suppliers. I see he is now doing other modules beyond temp/humidity.

I've been really impressed with the one-wire stuff -- I don't think I've had a single failure/glitch in 3 years of continuous operation...

I've bought several/many parts fron Sheepwalk Electronics - a great little firm   1-wire is great too - used it for my DIY weather station

[SnakeyJ]

+1 for the Lascar ELUSB-2, we have four of these at work which I brought 4+ years ago.   We use them a lot for environmental monitoring and they just keep working.

The only major drawback is the supplied software does not give much graphing flexibility - however it will export to CSV or Excel.     If anyone can recommend a good graphing util other than Excel I'd be interested (for customer reporting).    Ideally I would like to plot the data as multiple lines over a Mon-Sun x axis, which has eluded me in excel.

[MikeWilson]

Thanks everyone,

So it's either;

* 1 Wire - cheaper but more complex

* TEMPerHUM USB dongle - £14, needs calibrating. Works with existing software, perhaps easier to operate than Lascar.

* Lascar - more expensive but reliable, and standalone (presumably if can monitor a remote location on battery power for several days and have the data analysed later..). Lacks existing software integration options

* Netatmo - most expensive, but reliable and lots of integration options

I've coveted the Netatmo, but I don't think I can justify it. I suspect that there's a Lascar in my future perhaps after the observatory has been built, but for the time being I might just pick up a cheap TEMPerHUM stick from eBay to "prove" the idea indoors, to check for any possible household damp/condensation issues and to play around with the data.

Thanks everyone for the heads up.

[Psychobilly]

The lascar can monitor over months or years but as you say isn't suitable for "realtime"....

Peter...

[FraserClarke]

One-wire is cheap to extend once you've got it set up, but you do need a USB dongle at ~£25 to start.

Only thing to be a bit aware of is that the temperature/humidity at the back of your PC probably isn't representative of the rest of the dome, due to the heating by the PC itself.  Close enough to get a rough idea of what's going on though.

[Gina]

1-wire will connect to a PC with  an adapter as has been said - I got mine from Sheepwalk Electronics OR connect directly to an Arduino for independent control and display.  The Arduino has a library specific to 1-wire that covers all the features and functions.   This is what I used for my independently controlled Peltier TEC cooled DSLRs.  Of course, the Arduino can also be controlled from a computer.  I also use 1-wire and Arduino for my DIY weather station.  I like 1-wire for it's infinite extendability and simplicity plus the fact that devices can be several hundred metres from the base station with just a twisted pair cable.  (1-wire means one DATA wire - it DOES need a return/earth/ground wire.  Though whether the return could be via an earth rod into the soil, I don't know - must try it sometime )