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gooby
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Arduino
I received my Adafruit Arduino experimenter's kit a few days ago and am very excited about this; getting up to speed on circuit theory so I can know
just what I'm doing when I get in there...
Does anyone else have an Arduino board? What have you done with them? Are there any tools I should have above and beyond the stuff that comes with the
package (here are the contents: http://www.adafruit.com/products/170). I'm thinking about getting an inexpensive multimeter but I'm not sure what one I should get or whether I
really need it for my purposes at this juncture...
Incidentally one of the nice things about Arduino is that you can get it to interface with RS232. A lot of chemical laboratory equipment speaks with
RS232 as well. That was the original motivation behind getting an Arduino ... "Santa's little helpers".
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zoombafu
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I have an arduino as well and I love it.. I have mine set up with a probing system (temp and pH). Go watch the videos by Jeremy Blum, they are
pretty good at explaining how to use it.
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gooby
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Quote: Originally posted by zoombafu  | | I have an arduino as well and I love it.. I have mine set up with a probing system (temp and pH). Go watch the videos by Jeremy Blum, they are
pretty good at explaining how to use it. |
It will be a long time before I can really invest in a chemistry lab (for a number of reasons) but thank you, that's great.
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Paddywhacker
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It's something that I've been wanting to get into. You have seen the Youtube tutorial videos?
A possible project would be an auto-titrator.
A more ambitious one would be an Arduino-controlled fractional distillation setup. Monitor the drip rate to control the temperature. Monitor the
temperature slope (and/or the drop count) to control changing the reciever, monitor for abnormal conditions to abort.
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Yo-Yo
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I have several arduinos and use them liberally. The reason I first bought it was to use as part of a diy centilever scale. It is possible with small
means to build a balance with quite high presition and sensitivity by bouncing a lightbeam on a reflecting centilever and then reading the reflected
light using aphotodiod. Obviously, the amount of light hitting the detector is dependent on the reflection angel and hence on the load of the
centilever.
I took a PhD in neuropharmacology and all I got was this bloody t-shirt.
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Yo-Yo
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I have several arduinos and use them liberally. The reason I first bought it was to use as part of a diy centilever scale. It is possible with small
means to build a balance with quite high presition and sensitivity by bouncing a lightbeam on a reflecting centilever and then reading the reflected
light using aphotodiod. Obviously, the amount of light hitting the detector is dependent on the reflection angel and hence on the load of the
centilever.
I took a PhD in neuropharmacology and all I got was this bloody t-shirt.
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smaerd
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Paddywhacker I was thinking of something pretty similar. I was thinking of a way to rig an arduino to automate a reaction to be with-in a certain
temperature range using a heating mantle.
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Paddywhacker
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| Quote: Originally posted by smaerd | | Paddywhacker I was thinking of something pretty similar. I was thinking of a way to rig an arduino to automate a reaction to be with-in a certain
temperature range using a heating mantle. |
What I like is that you have so many input channels. You can put a thermocouple or thermister at the top of your reflux condenser to switch the power
off if it rises, protecting against loss of coolant, condenser flooding and thermal runaway in your reaction.
You can put other thermocouples around to monitor the heating bath and to monitor for fire.
And you can get a nice record of your temperature curves to display in Excel.
Double points if you can write it up here with pictures.
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gypsyNo2
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This might interest some people
http://myspectral.com/
Enjoy
GypsyNo2
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IrC
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I have been checking for a while and I still see no software available. Do you have any idea when they will make it available? From the page: "We are
working on final touches to the opensource software made with Processing language. We will provide a generic tool, which you can fork and modify for
your own applications". Been a while and still no links. All I see is too vague to aid in building one, looks more like an ad for a product they will
have for sale rather than a cool project we could build.
As you know this is just a pile of parts with no code for the Arduino. Without any application software for the computer to display data there is even
less of an incentive to build this design. Sad because I really want to be playing with the completed project, what a useful tool this would be.
On a side note I have 3 Arduino Duemilanove's and a couple UNO's. As well I have several prototyping shields, sensor shields, 4 servo, 4 relay, as
well as you name it about every type of sensor shield out there. My problem is to afford all these toys I must buy them on fleabay from China which
means nothing in terms of data or documentation. Things like schematics, and templates for the boards showing interconnections such as on the
prototyping shields.
For example one has two switches, two LED's, SMT foil patterns but to know how to actually wire a circuit I have to trace each board out. With crappy
vision and tight foil patterns this is nearly impossible. Where can I find useful information since the sellers are virtually worthless on this topic.
Once in a while I can look at the auction pages of a dozen different sellers listing similar items and glean some information. I am really tired of
searching online because what I find is usually too general to help with a specific item I have.
Still the best way to go if you are getting into this area since for example the $85 package listed by gooby is a lot to pay. If you look on the site
for say a single UNO R3 it is twice the cost of my fleabay sellers and they do not give the data I am looking for if I bought their item any more than
the sellers in China do. You have to buy the whole package to get the paperwork with the board. I don't know maybe I should bite the bullet and pay
twice the cost for another Arduino Duemilanove or UNO in one of the experimenter kits just to get the data they send with it.
Anyone out here with paperwork or software they can post for some of these boards?
I should make a plug for the fleabay seller bunnyhey, so far they do the best at providing what they can if you remember when paying to add a note
requesting it. Not to mention some of the lowest prices. The order I received from them yesterday took 6 days coming from China to land in my PO box
in Arkansas, not too bad at all.
[Edited on 9-14-2012 by IrC]
"Science is the belief in the ignorance of the experts" Richard Feynman
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watson.fawkes
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| Quote: Originally posted by IrC | | Things like schematics, and templates for the boards showing interconnections such as on the prototyping shields. |
Duemilanove documentation is on the Arduino site page for it. See the links under "Schematic & Reference Design". I've never needed the EAGLE files (the CAD system); the
schematic itself has always sufficed. The Uno docs are on there as well somewhere (Duemilanove shows up easier in a search).
I'd guess most of the shields you've got are simple clones of open source designs. If you just started collecting all the docs for such boards, you
should be able to match them up pretty easily.
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IrC
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Thanks watson.fawkes, pretty much I have downloaded local copies of nearly that entire site. My greatest need I have yet to find is templates for two
of the prototyping and sensor shield boards. Since they plug on top of the Arduino the pins are easy just by going from the pins on the Arduino. But a
template which shows where all the foil paths from the SMD patterns on the prototyping boards is impossible to find forcing me to actually trace the
paths one by one. Like I said very hard when my vision is not so good any more.
"I'd guess most of the shields you've got are simple clones of open source designs."
I cannot find a diagram of the sensor shield boards in anything generic on that site which corresponds to the ones I have. This will be much more
difficult to trace than the prototyping boards. I just wish the sellers out there would do better at providing documentation for their products.
"I'd guess most of the shields you've got are simple clones of open source designs. If you just started collecting all the docs for such boards, you
should be able to match them up pretty easily."
Yes that's something I found out a while back by searching, which has been of great help.
Forgot to add I just received 3 of the Arduino Mega 2560's yesterday. Been thinking what a great board with all the I/O to do something like turn a
house into one of those Christmas displays like the Wizards in Winter display I say on Utube a few years ago. I do wish they would get up to 12 bit
A/D on board for some of the discriminating metal detector ideas I am playing around with.
The sensor shield board (I bought 2 of them) was only $5.88 free shipping. However nothing in the form of documentation is provided by the seller,
forget their name but a different seller than the one I mentioned previously.
[Edited on 9-14-2012 by IrC]
"Science is the belief in the ignorance of the experts" Richard Feynman
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triplepoint
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IrC said: I have to trace each board out. With crappy vision and tight foil patterns this is nearly impossible.
IrC, have you considered photocopying or scanning the boards? You may be able to blow them up to a more manageable size to see, as well as having a
convenient place to write notes. I don't know for sure that it would work, just a thought.
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IrC
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Would be handy if I had a blank board. Not so easy stuffed with pin headers and other parts.
Still, not a bad idea. Think I'll dig out my closeup lens assortment and one of my Sony DSC-F717's. They do closeups well and blowing it up would at
least make some of the tracing routes simpler. Why didn't I think of that.
[Edited on 9-14-2012 by IrC]
"Science is the belief in the ignorance of the experts" Richard Feynman
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watson.fawkes
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| Quote: Originally posted by IrC | | I cannot find a diagram of the sensor shield boards in anything generic on that site which corresponds to the ones I have. This will be much more
difficult to trace than the prototyping boards. I just wish the sellers out there would do better at providing documentation for their products.
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That looks like the sensor shield for the Electronic Brick series that Seeed Studio sells. Schematic
available on their wiki page for the product.
The expectation that someone cloning an open source design to say so explicitly in not based in reality. They're putting in as little effort as
possible already. Their whole business model is about appropriation; it's not like they have any interest at all in touting that, or even disclosing
it, for that matter.
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IrC
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Thank you very much. That information for the sensor shield is exactly what works with what I see now is a clone. I had no data whatsoever until you
gave that link and after a little study I see it perfectly matches what I bought. What you say makes sense and explains why they suck at providing
data for their products. Now I can take full advantage of the features on the two I have. No doubt it does not make the original designer happy but I
am glad they put out that Wiki page.
"Science is the belief in the ignorance of the experts" Richard Feynman
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watson.fawkes
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| Quote: Originally posted by IrC | | No doubt it does not make the original designer happy but I am glad they put out that Wiki page. |
A specific
strategy to consider. When you buy future things in this area, you could select a product from the manufacturer's site, check the documentation to
ensure that it's what you want (and that you have a copy in the first place), and then go shopping for a clone. This is a perfectly rational strategy
to optimize the gap you've already experienced, given the facts on the ground about how these things are designed and manufactured.
Now on the other hand, there are voices from the OSHW (open source hardware) movement that consider cloning a Bad Thing and are trying to exert some
kind of moral suasion not to do it and not to buy it. This is nothing but a modern day temperance sensibility, a kind of abstinence teaching. We all
know how those have all worked out in the past. These attitudes just aren't well grounded in harsh reality. When you publish not only
schematics, but also board art and a detail bill of materials, it's a fantasy not to expect clones.
The interesting question, to my eye, is whether this model is sustainable. The presence of clones means that you shouldn't expect revenue past an
initial period of product introduction, before it's know whether the idea has traction or not. And there's a middle period (where we are now), where
brand awareness gives a certain amount of revenue in the presence of clones. At the very least, it's clear that any sustainable pattern here has a
large churn of individual products. So the more specific question is whether there's enough revenue in the early stages to pay for the engineering. It
seems that there may be.
The further irony is that Seeed Studio is located in Shenzhen, a likely location for where the folks that cloned their board are. And even more, Seeed
has their own versions of the Arduino, some plug-compatible with standard-pattern shields (Seeeduino), some in different form factors. Their company
itself leveraged itself off other people's work, including not only the hardware design, which they modified, but also the software, which they use in
its entirety.
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smaerd
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So I put some time into thinking of the idea I had earlier(maintaining a reaction temperature in +/-5*C). Here's what I came up with but before I
consider investing I'd love to hear a little input from the people on here  .
I decided I would put a relay after the rheostat/glas-col controller and before the heating mantle. In another circuit I decided I would have a slide
potentiometer in parallel with an arduino and a stainless steel thermistor probe(which is in a flask's side-arm or condenser via thermometer adapter)
. Thermocouples in general need an integrated circuit to work with arduino's which would add another 20$ to the design whereas a thermistor just
needs some code tweaking.. The arduino controls the relay in the other circuit.
How it should function:
A slide potentiometer will be calibrated to degree's Celsius and have a scale next to it so the temperature can be set. The arduino reads the
resistance of the potentiometer and stores this value as the temperature to maintain. It then reads the thermistor and if the temperature exceeds the
value by 4-5*C it opens the relay for the heating mantle effectively cutting the power. If the temperature is lower then or equal to the set
temperature value it closes the relay or does nothing if the relay is already closed. It could also be programmed to track temperatures maybe, such as
if a run-away is occurring and the temperature leaps 10*C in 1 second it could cut the power and maybe sound off a cheesey buzzer until a button is
pressed saying that it's okay.
I was thinking it would be nice to set up a little LCD to display the current temperature and the set temperature range but I have never worked with
anything like that before. It would probably help with debugging as well.
My biggest concerns are, would using a relay to cut power be enough? Would a glas-col rheostat be able to handle this? I would have ideally used a
voltage controlled resistor but looked into it and it seems mythical, then switch gate capacitors flew over my head so I figured off and on was more
with-in my range.
[Edited on 20-9-2012 by smaerd]
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watson.fawkes
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| Quote: Originally posted by smaerd | a stainless steel thermistor probe [...] Thermocouples in general need an integrated circuit to work with arduino's which would add another 20$ to the
design
[...]
My biggest concerns are, would using a relay to cut power be enough? Would a glas-col rheostat be able to handle this? I would have ideally used a
voltage controlled resistor but looked into it and it seems mythical |
I don't want to be insulting, but there
are two pathways here. (1) Get temperature regulation as simply as possible, or (2) Learn how to build temperature regulation so that you can do more
than simple COTS (commercial off the shelf) solutions. In this case, trying to roll your own to make something that's cheaper than COTS is not
worthwhile. For you, I recommend option (1) because it's clear to me that you don't know enough about the field to make option (2) anything but very
frustrating. You might consider option (1) as the very cheapest education course on temperature control that it's possible to purchase.
Option (1). The COTS solution is three parts (a) a commercial, panel-mount (1/16 DIN), Chinese-made PID controller from eBay. These can be had for $40
or less, hardly more than an Arduino, and they already have a display and software that works. Part (b) is a temperature sensor, either RTD or
thermocouple, that's compatible with the PID. Inexpensive thermocouples can be had for less than $5, though you might want to pay more for longer lead
length and longer probe length. Part (c) is a solid state relay, also Chinese-made, for $6-8. Those are the main parts, though you also need a case,
switch, etc. Nevertheless, this is easily the cheapest entry, assuming you value your time at more than $0.25 per hour.
Option (2). Design and build one. Only do this if you need more than simple thermostat control. There are various reasons to do this, but if you don't
already know the reason, you probably don't have one. You haven't stated one, certainly. And you have greatly underestimated the utility and
importance of calibration in a piece of gear like this. But you have stated one feature that's not in standard controllers, namely, runaway sense. One
feature does not rise to a proper reason, in my book. And frankly, this feature seems like a kind of false insurance, since if you're not anticipating
a runaway, you're probably also not anticipating many other serious problems. But whatever. If you want to try this, I'd recommend the osPID project, an open-source PID controller. You can augment its existing firmware with your feature. This will be much cheaper than redesigning
a controller from scratch.
And now for the newbie concerns:
Never use a mechanical relay for variable-heat applications. They'll wear out very quickly. That's the reason for using an SSR with the PID
controller.
As long as your supply voltage works with your mantle at 100% duty cycle (that is, just plugged in), switching it on and off won't be harmful. There
can be lifetime issues with switching certain kinds of heating elements, but the nichrome family aren't one of them.
As for variable resistors, OUCH! Using a resistive ballast for variable heating is just crazy. Simply apply Ohm's law and estimate how much power
would need to be dissipated in the ballast resistor.
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smaerd
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No insult taken, rather, much appreciated. I don't want to de-rail the thread(as now my interests are not arduino based) but I highly value your
advice and will be looking into your suggestions.
The runaway idea was just something else I thought off while posting. Cutting the power during a runaway isn't going to do much anyways. This isn't an
idea born out of necessity but it would be a fun project and would be useful for maintaining reaction temperatures assuming it works. Would be nice
for reactions in DMSO as it decomposes before boiling and fiddling with the rheostat and checking the thermometer can be a bit tedious at times.
Was checking out those solid state relays the other day, looked like a good solution.
About the voltage controlled resistors this will make you laugh I was originally researching MOSFET's for this  , only took a couple calculations to realize how far into the wrong field I was. Anyways, thanks again, really
appreciate you giving good hints!
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IrC
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You might take a look at these links.
http://www.twopossibilities.com/2011/01/26/homebrew-temperat...
http://arduino.cc/playground/Main/BarebonesPIDForEspresso
http://fermentationriot.com/arduinopid.php
http://letsmakerobots.com/node/30810
"Science is the belief in the ignorance of the experts" Richard Feynman
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smaerd
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Very cool IrC. the http://fermentationriot.com/arduinopid.php is exactly what I was talking about minus the ethernet interface and add an LCD. Go figure people
already had a PID library for the arduino. The graph looks pretty good definitely within the range of error I was looking for.
@Watson.Fawkes: Where can I learn some more about actual PID's?
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watson.fawkes
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The proportional-integral-derivative terminology comes out
of control theory, which I'd recommend reading something about (like the linked Wikipedia article) first, since it gives the overall setting and will
allow you to make easier sense of PID control specifically. It's still an active area of research, and it has the lovely property that starting with
very simple ideas you quickly reach very deep mathematical questions. (At least that's lovely for a mathematician.) Control theory has many
applications, starting in the 19th century with the analysis of mechanical governors and still vital today in the design of switching power supplies.
After that, the Wikipedia page for PID control is as good a starting point as any. It's probably more than you need right now, and it has plenty of references.
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IrC
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http://www.ebay.com/itm/Digital-PID-F-C-Temperature-Controll...
Will not last too long but I thought you should look at this controller.
This alcohol sensor for Arduino is interesting. They have other gas sensors as well.
http://www.ebay.com/itm/MQ-3-Gas-Sensor-module-Alcohol-Ardui...
LPG, Propane and Hydrogen
http://www.ebay.com/itm/MQ2-Gas-Sensor-module-LPG-Propane-an...
Methane, Butane and Propane
http://www.ebay.com/itm/MQ-5-Gas-Sensor-module-Methane-Butan...
carbon monoxide
http://www.ebay.com/itm/MQ-7-Gas-Sensor-module-carbon-monoxi...
Pollution Sensor Module
http://www.ebay.com/itm/Pollution-Sensor-Module-/13054531050...
Smaerd if you can get a copy of the book listed below project 22 titled 'LCD Thermostat' is perfect for you. Code to run it listed. I scanned pages
125 to 131 but cannot post it here as each scan is around 2.5 mb in size. Lower resolution scans are not worth using as it is too hard to read.
"30 arduino projects for the evil genius"
There is a fairly fast torrent for it out there.
[Edited on 9-23-2012 by IrC]
"Science is the belief in the ignorance of the experts" Richard Feynman
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IrC
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No idea why more are not discussing this most interesting topic but on that note I will go back to ragging on how little info and support the bulk of
the low cost sellers on fleabay provide.
Does anyone actually know what the pollution sensor is looking for? PDF link to info provided for it.
Attachment: pollution sensor.pdf (194kB)
This file has been downloaded 3946 times
"Science is the belief in the ignorance of the experts" Richard Feynman
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