Firewolf4 Posted July 26, 2009 Share Posted July 26, 2009 Looks like we have the probes on the way and have overcome any differences. I have some very good pricing on probes and should be able to sell PH and EC for about $25. Orp will be a bit more but I don't really understand why until I see them. They are all listed as Laboratory grade. They are also sending me a Dissolved Oxygen probe. I'm not sure if we will make a circuit for it but the probe is coming. Once I have the EC in my hands we should be able to wrap up the final PCB design and send it out for the first boards. Steve Steve, How hard would it be to make each of the probe circuits interchangable sub assemblies? Lets say you want pH, ORP and say magnesium (ion specific probe). If it can be designed with internally changable sub assemblies that all utilize 3, 4 or 5 leads each then it would make the probe portion completely customizable and upgradable down the road. Estimate that a sub assy would contain the BNC, sub PCB, specific probe support components and a 5 pin header. The firmware changes would be akin to writing code saying "in PortA=pH, In Port B=ORP" etc. and Yes, the past 2 weeks I've been slammed with work averaging 19 hrs a day so no urgency for the PCB updates Link to comment
hcsceo Posted July 27, 2009 Author Share Posted July 27, 2009 Steve,How hard would it be to make each of the probe circuits interchangable sub assemblies? Lets say you want pH, ORP and say magnesium (ion specific probe). If it can be designed with internally changable sub assemblies that all utilize 3, 4 or 5 leads each then it would make the probe portion completely customizable and upgradable down the road. Estimate that a sub assy would contain the BNC, sub PCB, specific probe support components and a 5 pin header. The firmware changes would be akin to writing code saying "in PortA=pH, In Port B=ORP" etc. and Yes, the past 2 weeks I've been slammed with work averaging 19 hrs a day so no urgency for the PCB updates that is a crazy awesome idea. That way a person could have any configuration they wanted and it could support future probes out of the box. All we would need is a four pin header with +12v, -12v, GND, and voltage back to I/O. Then write the code to enable which function is on what port. We could design a basic pcb module dimension that all circuitry would have to fit on to be compatible with our main board. Lemme finish these two circuits and let's expand on that. The only additional cost would be the additional pcb. I'm guessing it would only be like 1 square inch each. Steve Link to comment
Vancouver Reefer Posted July 27, 2009 Share Posted July 27, 2009 You could even put a different value voltage divider on each board so when you plugged in a board the Arduino would recognise what type of board it is by the analog voltage it receives. All you would need to use is an additional analog pin. Thats what i was planning to do on a commercial version of mine before i gave that idea up and made it just for me! VR Link to comment
evilc66 Posted July 27, 2009 Share Posted July 27, 2009 That would make things horribly simple. Link to comment
buteohawker Posted July 31, 2009 Share Posted July 31, 2009 This is a very in depth project. I dont know if you can make the deadline but you might want to enter it in this arduino project contest Link to comment
hcsceo Posted July 31, 2009 Author Share Posted July 31, 2009 This is a very in depth project. I dont know if you can make the deadline but you might want to enter it in this arduino project contest Do you have a link? Link to comment
hcsceo Posted August 2, 2009 Author Share Posted August 2, 2009 No real update here. I haven't worked on this project in a couple of weeks as I had been preparing our companies layoffs. I HATE layoffs. Even if you are not getting the axe it is still very stressful. Godspeed for those who left us. I am only waiting on my EC probes to finish this up. I have confirmation from China that they shipped last week so they should be here soon. At this point I'm sure we will NOT make the September 1st deadline mainly cause we have been monkeying around with these probes. Once I have the probes in hand I'll be able to set a new deadline. Thanks for looking. Steve Link to comment
hcsceo Posted August 6, 2009 Author Share Posted August 6, 2009 UPDATES.. OK, the EC probes finally made it from China, YAAAAY!! Last night I was busy and installed the ICL7660A's and they worked flawlessly. Very little voltage drop between the positive and negative with +12.2 on the positive side and -12.0 on the negative side. In fact power must have been an issue cause now the PH and ORP reading are rock stable with my first night of testing. I also wired a CAT5 cable to my test system and ran it out to a breadboard with my EC circuit. I haven't tested the EC probe yet as I was busy rewiring a bunch of stuff last night. Hopefully, if all goes well I should have everything buttoned up by next weekend so firewolf4 can finally get working on the PCB layout for me. The plan is this. Once we have the PCB's back, built, and tested I'll put together the first kits to be available for purchase and we will release all the code and schematics as open source so you can build your own. I won't be updating the release date until firewolf4 has what he needs in his hands to finalize the PCB design. Sorry for the secrecy on the designs and code, but sometimes the easiest way to meet a deadline is to not get a bunch of input for the initial release but instead get public input and make changes for the next revision. Steve Link to comment
Marian Posted August 7, 2009 Share Posted August 7, 2009 UPDATES.. OK, the EC probes finally made it from China, YAAAAY!! Last night I was busy and installed the ICL7660A's and they worked flawlessly. Very little voltage drop between the positive and negative with +12.2 on the positive side and -12.0 on the negative side. In fact power must have been an issue cause now the PH and ORP reading are rock stable with my first night of testing. I also wired a CAT5 cable to my test system and ran it out to a breadboard with my EC circuit. I haven't tested the EC probe yet as I was busy rewiring a bunch of stuff last night. Hopefully, if all goes well I should have everything buttoned up by next weekend so firewolf4 can finally get working on the PCB layout for me. The plan is this. Once we have the PCB's back, built, and tested I'll put together the first kits to be available for purchase and we will release all the code and schematics as open source so you can build your own. I won't be updating the release date until firewolf4 has what he needs in his hands to finalize the PCB design. Sorry for the secrecy on the designs and code, but sometimes the easiest way to meet a deadline is to not get a bunch of input for the initial release but instead get public input and make changes for the next revision. Steve Steve, glad to notice your progress. Can you please let me know what schematic you used for pH. I have tried several and I was not really happy. They are capable of reading between 1 and 14 with a rather reduced resolution. For as, the 7.5 - 8.5 range is important and a 0.1 error tends to be significant. We need to control the gain as well as the slope. Thank you. Marian Link to comment
bad inferno Posted August 7, 2009 Share Posted August 7, 2009 ph ORP Isolation...I was thinking instead of using a voltage output from these cct's you could use a voltage-to-frequency IC. This would allow a 7,000 - 10,000hz output through an otpocoupler and straight into a DI pin of the processor. So having a DC-DC isolator for the power supply as you mentioned and a freq output would mean the ADC inputs of the arduino would not provide a common between the cct's. PC interface: If you enabled a serial output to a PC we could use zigbee to provide a wireless link between the PC and the controller. I have done some development on a web interface using dallas 1wire over the last few years. www.rjconway.homeip.net Looking forward to the cct's when posted. Link to comment
hcsceo Posted August 7, 2009 Author Share Posted August 7, 2009 Steve, glad to notice your progress. Can you please let me know what schematic you used for pH. I have tried several and I was not really happy. They are capable of reading between 1 and 14 with a rather reduced resolution. For as, the 7.5 - 8.5 range is important and a 0.1 error tends to be significant. We need to control the gain as well as the slope. Thank you. Marian You should be able to adjust the slope and offset to run between those parameters without issue and get more resolution this way, however I'm not sure a 0.1 error would be to significant given the fact that most tritration tests could fall outside of this error easily depending on how it is administered and the perception of color. Temp compensation would be a more important factor I think in the end along with proper maintenance of the probe. What I found to be the most helpful is to read the probe 10 times and average the reading. This really smoothes out the probe and zeros in on a very accurate PH. The PH schematic I'm using is widely available on the internet and works very well. At first I made a bunch of changes to it then after being told about the ICL7660A's I've rewired everything to be identical to it and found it very good. The only changes I've made at this point is to add filter caps to the power inputs. The quality of the negative voltage is very important in my testing. Here is the link PH meter Hope this helps I'll be glad to help you any way that I can. One thing you want to keep in mind about the PH range is that some people will want to use the second PH to control a CO2 reactor and the PH readings need to be lower for this if the probe is inside the chamber. Steve Link to comment
hcsceo Posted August 7, 2009 Author Share Posted August 7, 2009 ph ORP Isolation...I was thinking instead of using a voltage output from these cct's you could use a voltage-to-frequency IC. This would allow a 7,000 - 10,000hz output through an otpocoupler and straight into a DI pin of the processor. So having a DC-DC isolator for the power supply as you mentioned and a freq output would mean the ADC inputs of the arduino would not provide a common between the cct's. PC interface: If you enabled a serial output to a PC we could use zigbee to provide a wireless link between the PC and the controller. I have done some development on a web interface using dallas 1wire over the last few years. www.rjconway.homeip.net Looking forward to the cct's when posted. bad inferno, thatnks for your input. I thought about this idea and using the Analog to Digital convertor to read this information. The only stumbling block for me is that it was outside of my scope of reference and I just don't know how to do it. I know the Dallas One Wire Temp probe that we use does this and the one wire library should be able to do everything we want but the learning curve seemed to be large for me. I've tried those DC-DC isolators and they don't work right for analog without a common ground between the controller and the op-amp (which nullifies the need for them LOL). I suspect the different ground potentials is screwing up the readings when using them. I think once the reference designs are released lets work on getting this Analog to Digital working correctly as this will be the solution for the Isolation we want. Since I have changed to the ICL7660A's the problem I was experiencing before has resolved itself. When you put the probe in it does make the PH move a bit but then it settles back down within seconds. It is something we want to fix but it isn't a deal breaker right now. I'll check out your link tonight and see what you are working on. Link to comment
hcsceo Posted August 7, 2009 Author Share Posted August 7, 2009 OK, I worked on the EC meter all night. The problem is this. The reference design we are all looking at is really designed for freshwater aquariums and reads about a max of 3ppt. For those of you who are thinking of using the circuit designed by isabella you are in for a treat. The first part of the opamp design that creates the AC is good, the second part that provides the gain for the probe is not right for our uses, the third part that converts to DC I believe is ok, and the fourth might need a little work that provides slope. The problem is with the 6.8k resistor between pins 6 and 7 in the gain loop. My plan is to replace that resistor with a pot so that I can adjust my probe ohm reading to 680 @ 40ppt. This should put the rest of the circuit back into alignment and correct the slope issues I am having. This is just a heads up for those of you working on this for your own projects. Anyway, I'll update more this weekend. Steve Link to comment
Margrave Posted August 7, 2009 Share Posted August 7, 2009 I don't recall if the AC control method was ironed out, but I ran across this setup for another arduino-based reef controller. Will it be possible (via the usb port or something) to upload the readings to a computer? It's been talked about, but I couldn't find a definitive answer. -Margrave Link to comment
hcsceo Posted August 7, 2009 Author Share Posted August 7, 2009 I don't recall if the AC control method was ironed out, but I ran across this setup for another arduino-based reef controller. Will it be possible (via the usb port or something) to upload the readings to a computer? It's been talked about, but I couldn't find a definitive answer. -Margrave Yes I have AC sorted with all solidstate circuits. It provides zero crossover switching and has a snub circuit. It isn't fully tested yet but is working as we speak. The snub circuit should improve the typical solid state design when working with inductive devices like motors. These tend to hang up solid state relays and keep them open. This design should be much improved over mechanical switches in that it should work much longer. Once I get the main controller done I'll focus attention on it. That link you provided I believe is jener8tionx's controller. Very nice setup and I believe he has made some more progress on his deal since I last saw it. On one of the threads I noticed a Make project link that I believe is an update of his box. Maybe he can chime in. Do a search for "automated reef controller build" in NR and I believe you will find it there. There is some very good information on that thread and these guys have done a lot of research to get where they are. I hope I didn't upset him earlier with my "armchair attorney" comment as I didn't mean to offend him and really admire the work he has done. To answer your second question, yes we will have readings sent to the USB and TX/RX ports on the arduino. So addition of ethernet cards that transmitt serial data and capturing data from USB is possible. Steve Link to comment
hcsceo Posted August 7, 2009 Author Share Posted August 7, 2009 I couldn't wait to get home to tests the EC circuit with my ideas, so I left work early and headed to Chili's for a Margarita for brain nurishment and then home to make my changes. The result is.... IT WORKS I made four samples of test solutions. a 40ppt, 30ppt, 20ppt, 0ppt. 40ppt reads 2.0 volts, 30ppt reads 1.5 volts, 20ppt reads 1 volt, and 0ppt is 0 volts. Multiply volts by 2 and again by 10 and you have ppt. My 30ppt kept reading 1.6 volts which would have translated to 32ppt and I couldn't figure it out. I went back and tested my sample with my refractometer and it was 32ppt. Although the circuit is working fine I would like to modify it so that it reads 40ppt to 4 volts, 30ppt to 3 volts, etc. I'll play with it some more, but for now it looks like the last major hurdle is overcome. Some more good news today. I talked with my friend that is completing the menu coding and he has solved the RAM issue. Right now our code with existing menu is only 14k. With menu loaded we never get over 800 bytes at this point. The code is very elegant and we are very excited to release it when complete. So all that is left is to try and modify the voltage output on the EC to get it to the volts I like, test switched outputs again, and button it up. We should be on schedule to get the final schematics to firewolf4 for PCB work by the end of next week. Thanks for everyone's support. We are getting very close now. Steve Link to comment
ajmckay Posted August 7, 2009 Share Posted August 7, 2009 Wow it's been at least a month since I've checked up on this thread. Sounds like things are coming along nicely. In my quest to build an arduino-based controller I am still trying to source some cheap solid state relays... Good luck and I'm excited for the release! Link to comment
Vancouver Reefer Posted August 8, 2009 Share Posted August 8, 2009 If you only looking for a couple of amps look here: http://www.alliedelec.com/Search/ProductDe...G3MB-202PL+DC12 They are 2A which will be good anough for alot of the pumps used in our industry!!! Hope this helps, VR Wow it's been at least a month since I've checked up on this thread. Sounds like things are coming along nicely. In my quest to build an arduino-based controller I am still trying to source some cheap solid state relays... Good luck and I'm excited for the release! Link to comment
hcsceo Posted August 8, 2009 Author Share Posted August 8, 2009 OK I cleaned up my breadboard and connected it to the arduino and wrote the code and now I have a good value to the screen for PPT. I'm going to try and get a video together of the home screen with all the info and a sneak peek of the menu next week after I get the schematics updated. Hopefully my kids won't pull all the parts off the breadboard, LOL. Link to comment
Firewolf4 Posted August 9, 2009 Share Posted August 9, 2009 I couldn't wait to get home to tests the EC circuit with my ideas, so I left work early and headed to Chili's for a Margarita for brain nurishment and then home to make my changes. The result is.... IT WORKS I made four samples of test solutions. a 40ppt, 30ppt, 20ppt, 0ppt. 40ppt reads 2.0 volts, 30ppt reads 1.5 volts, 20ppt reads 1 volt, and 0ppt is 0 volts. Multiply volts by 2 and again by 10 and you have ppt. My 30ppt kept reading 1.6 volts which would have translated to 32ppt and I couldn't figure it out. I went back and tested my sample with my refractometer and it was 32ppt. Although the circuit is working fine I would like to modify it so that it reads 40ppt to 4 volts, 30ppt to 3 volts, etc. I'll play with it some more, but for now it looks like the last major hurdle is overcome. Some more good news today. I talked with my friend that is completing the menu coding and he has solved the RAM issue. Right now our code with existing menu is only 14k. With menu loaded we never get over 800 bytes at this point. The code is very elegant and we are very excited to release it when complete. So all that is left is to try and modify the voltage output on the EC to get it to the volts I like, test switched outputs again, and button it up. We should be on schedule to get the final schematics to firewolf4 for PCB work by the end of next week. Thanks for everyone's support. We are getting very close now. Steve I'm waiting with baited breathe for the updated files . I will be out of Town (in Chicago for work seminars) from the 18th through 23rd of this month. If my laptop could handle either of the CAD programs I'd work on them at the hotel. Link to comment
hcsceo Posted August 16, 2009 Author Share Posted August 16, 2009 I'm waiting with baited breathe for the updated files . I will be out of Town (in Chicago for work seminars) from the 18th through 23rd of this month. If my laptop could handle either of the CAD programs I'd work on them at the hotel. You have email One big step closer guys!! Link to comment
Militant Jurist Posted August 16, 2009 Share Posted August 16, 2009 You have email One big step closer guys!! Do you have an updated ETA on when this will first be available to a first generation purchase? I'd love to use something like this, but I'll need to start saving my pennies! And dig out my soldering iron Link to comment
spk9 Posted August 16, 2009 Share Posted August 16, 2009 Great project and I cannot wait to see the final product. I'm new to nanos and controllers (have been running 75g reef tank manually for many years) and was just starting to look into an Arduino based system. Are you selling the plans, or are you going to sell finished product? Too hard to find that in the 10 pages of posts. Thanks! Do you have an updated ETA on when this will first be available to a first generation purchase? I'd love to use something like this, but I'll need to start saving my pennies! And dig out my soldering iron Link to comment
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