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GENERAL CHEESE MAKING BOARDS (Specific Cheese Making in Boards above) => EQUIPMENT - Making Cheese => Topic started by: chucklawrence on June 17, 2015, 02:36:43 PM

Title: USB pH sensor
Post by: chucklawrence on June 17, 2015, 02:36:43 PM
Has anyone tried using pH sensors that hook into a pc or mac?  Like this one for example: http://www.vernier.com/products/sensors/ph-sensors/ph-bta/ (http://www.vernier.com/products/sensors/ph-sensors/ph-bta/)
Title: Re: USB pH sensor
Post by: IllinoisCheeseHead on June 17, 2015, 09:00:04 PM
Hi

Nice probe.  I would be concerned with such a high range inaccuracy.  They are saying .02 plus or minus.  That means you could be off by .2 either way from actual numbers.  Since .1 translates to 10 times more acidic or more alkaline, being of by .2 would be far more than I would tolerate :)

Thanks
Title: Re: USB pH sensor
Post by: chucklawrence on June 17, 2015, 11:01:55 PM
Yeah, I don't really mean this EXACT one but a pH probe that hooks in via USB
Title: Re: USB pH sensor
Post by: Kern on June 18, 2015, 12:15:36 AM
Here are the specifications copied from the link you furnished:

    Type: Sealed, gel-filled, epoxy body, Ag/AgCl   :)
    Shaft Diameter: 12 mm OD   :)
    Response time: 90% of final reading in 1 second   ^-^
    Temperature range: 5 to 80°C   :)
    Range: pH 0–14   :)
    Accuracy: +/- 0.2 pH units   :(
    Isopotential pH: pH 7 (point at which temperature has no effect)   :)

I read the accuracy to mean that with an actual pH of 5.5 this unit could read it as 5.7 at one test and then 5.3 a few minutes later.  That's what +/- 0.2 pH units means.  For cheese making you've got to be down into the +/- 0.05 pH unit accuracy range with appropriate reproducibility in the same range. 

I have no objections to using a USB probe so long as it is a good pH meter.  The one in your link is not a good one.   :(
Title: Re: USB pH sensor
Post by: jmason on June 18, 2015, 02:37:02 AM
I looked after reading your post and cheap chinese electrodes, that sell for like 8 bux and get the same or better accuracy, only difference is the bnc connector rather than usb.  USB is not magic, it's a serial interface with a 5 volt power supply.  So for a fraction of the price you could rig one up with an arduino or raspberry pi and I'm betting someone has already written an open source code for both units to display and/or datalog.  This unit did not come with interface or software, the interfaces they listed almost doubled the price.  Personally I'd persue a better option.
Title: Re: USB pH sensor
Post by: Gürkan Yeniçeri on June 18, 2015, 10:46:35 PM
I think it is not necessary to attach a USB pH sensor in to my VAT. This would have been good for an aquaponics though.

For cheese making you can always learn titratable acidity on this thread (http://"https://cheeseforum.org/forum/index.php/topic,2586.msg20373.html") or after couple of make you will get the idea by the texture of the curd anyway.