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January 7, 2010
News - Engineering Roundtable - …
about 2 years ago
The Atlas probe AFAIK are comparable to the “higher end” I linked(except leads are shorter 1m vs 3m, may have changed), if you are patient and willing to deal with weeding out a few sources you can get these probes for less than or about $10. I am sure Atlas sourced these probes in this manor. In the end most of the probes are really the same, what does vary is the Ag alloy used in the electrodes, the molar strength of the HCL solution gel in the reading bulb, and what the salt bridge is made of (fabric or ceramic). Body material and lead length do play a role as well (dictated by application/requirements). The cheap ones use fabric and cheaper materials, and the molar strength is often too high erroding the reading electrode prematurely, the higher quality probes will use ceramic salt bridges and will have much tighter specs. I had one probe last just over 3 years in my Aeroponics reservoir. Every water change I took it out cleaned with soft toothbrush re calibrated and put it back in:) If you track the probes calibration slope vs ideal you can tell probe condition.
My 3 Probes choices are (from cheapest to most expensive)
K1B0 Style This one is a pretty good probe but the lead to pretty short and you shouldnt leave this submerged for long periods(reference can be refilled, so it can leak).
Mid Range, durable This one is a tough and durable probe, I had pretty good experience with it, it sometimes has issues reading right after shipping leave it upright for a few minutes and it should start reading as normal.
Higher End These are generally my favorite probes, they last forever, are of a good quality and aren’t too expensive for their performance! If you plan on doing long term in situ readings this is definitely worth the extra price.
If you need more lab grade probes I highly recommend Omega as the source. Their probes are very expensive, but are extremely high quality! Omega. Hope this helps some source more appropriate probes for their needs!
Not sure about the details, but I would guess the DFRobot unit is a tad bit better but harder to interface(you have to do pH calcs yourself, not terribly hard really), it uses tant caps which will have a better response over temperature variations and you can tune the interface to the probe. On the other hand I have no idea what op-amp they are using and what means they are using to create the negative rail, so it could be worse in this aspect. The atlas unit uses a pretty good op-amp for the job and has some smoothing and noise filtering built into the software. It can be susceptible to ground loops and mains hum, but so can they all. In the end most of the units are really similar, its how you interface the probe. I am go on for a long time about these things (if you check my site you will see why :). For a curve I make a couple interfaces one is I2C, and the other is basically a Leonardo with a pH front end (Native USB allows it to hook up to Tp-Link router for Wifi for example) which can be programmed however you need! Phidgets also makes a decent interface that is ORP select able :) Hope that helps you some!
I hate to toot my own horn but I have a very similar project using a few Sparkfun parts and my own pH interface. take a look at it here! DIYpHMeter Hope this helps give people some more options!
News - Enginursday: For those of…
about 2 years ago
Edit Config.sys (Increase XMS ratios so wing commander can run)
Edit Autoexec.bat (match sure the config.sys is loading in the right order)
News - New Product Friday: Sense…
about 3 years ago
I was actually referring to the probe, as there are some good buys even food grade out there. I have no doubts about the performance of their unit, standard proven design and I’m sure their algorithms are spot on to boot! In the whole scheme of things they are pretty reasonably priced, but they are not unique which I thought I would point out, for those that wish to support open source. I have a handy tutorial showing how this all works, even commercial meters are similar :)
I would be more then happy to meetup and explain it all and show off some of this stuff, who should I contact?
You shouldn’t compare the 2 units like that, at least not without including the specs too.
For $2 more you get a hell of a lot more capable pH sensor, know how and why it works and can verify the calculations or even use your own. On top of that you can use any old pH probe you want, not “restricted” to an overpriced one. I may carry them at some point, but there are some great buys already out there. I would also rather put my very limited resources towards more sensor types at this point.
LeoPhi at its heart is an Arduino, it started a few years ago as a simple atmega168 but grew into its big brother today. The USB features of the 32u4 spurred the latest revision and gives people the ability to simply plug it in and read pH, it really doesn’t get easier than that. Works on Raspis, hacked wifi routers(that $20 one, oh yeah!!), just about anything with a USB port. For ~$80 you can have a wifi pH meter/controller (probe, LeoPhi and a TL-WR703N) something the Atlas unit simply cant do. Pretty much the reason why it exists.
I really wish I could sell it cheaper but I am just one man with a full time job trying to support my passion, In fact I am finishing a batch of units to donate and need to pick up some stuff from you guys to finish, funny how that works. (Which leads into the 2nd design)
As an FYI, I have spent years researching, creating/failing, failing some more and finally succeeding, in creating open source water quality sensors. I hope to help create a safecast type system and increase the quantity and quality of monitoring, the new unit is geared for this and is significantly cheaper, with more to come.
I really encourage you guys to take some units and mess around with them, what do you have to loose? Besides supporting your customers and fellow OSHW makers is a good thing.
Sure thing, I’d be more then happy to bring some by for you guys to play with too.
LeoPhi pH interface/controller
and the result of a collaboration with ManyLabs/Wiregarden with some more on the way!
I2C pH interface
There are other open source options available if you would look around, one option is a city over from you guys :)
News - SparkFun and the DeLaMare…
about 3 years ago
I am currently trying to work with Anythink libraries to create mini hacker spaces inside the libraries. So far the Brighton branch has been awarded a grant and it looks like it will be a great addition to the libraries. Maybe Sparkfun would like to team up and we can start a new wave of education for the local communities and revitalize the library systems at the same time. I also donate quite a bit of hardware to teachers and soon to Anythink, for all those educators out there, there are a lot of makers like me looking to help!
No public wish lists :(
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