Computerized Nano, Mark II (LED Dimming 2-27-11) - Page 2
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Old 02-13-2011, 05:10 AM   #16
Robotguy
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Got a little more work done. The filter area is built and finally waterproof.

I wanted to have an o-ring seal but it just didn't work out. I ended up having to seal it up with silicone. Now I'll stuff it with a bit of foam and some kitchen scrubbers.


I also received my new LEDs and the "donor" lamp. This is the first prototype of the assembly:


There will be 4 or 5 of these across the top of the tank. Here's a shot with the LED lit, running at about 750mA:


And finally a lighting comparison with the filter running:


I want to make sure this thing has enough light to grow a nice carpet of HC. It looks like I'll have between 640 and 700 lumens about 12 inches from the substrate.

Has anyone seen the "Electronic regulators" from aquariumplants.com? I think I'm going to do something similar with an 88g co2 cylinder, a Leland regulator and a small Clippard solenoid. I'll leave the regulator set at a decent pressure, then use the microcontroller to open the valve for some percentage of the time, say 1 out of every 10 seconds. If I need more or less co2, I will adjust the duty cycle of the solenoid rather than adjusting a regulator or needle valve.
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Old 02-13-2011, 05:52 AM   #17
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A CO2 sensor to control CO2 concentration would be cool You don't have to worry about bubbles/sec and all that none-sense that we regularly go through.

http://www.parallax.com/Store/Sensor...8/Default.aspx

Maybe build it like a drop checker so it doesn't get wet but will get CO2 in the compartment or use a permeable membrane like the kordon breather bags. It will let gases go through not water.


I just read the specs for the CO2 sensor. It's only sensitive from 100 - 1000 ppm... We need it to be around 30ppm.. Neat idea though. If I can find one more sensitive, I'd give it a go.

Last edited by mistergreen; 02-13-2011 at 04:43 PM.. Reason: another thought
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Old 02-13-2011, 06:35 PM   #18
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Quote:
Originally Posted by mistergreen View Post
I just read the specs for the CO2 sensor. It's only sensitive from 100 - 1000 ppm... We need it to be around 30ppm.. Neat idea though. If I can find one more sensitive, I'd give it a go.
Wow, that's a bummer. I was getting excited about that sensor. I've been looking into ways to measure co2 for a while now. My current plan is to use a color sensor looking a a drop checker, but that seems a little roundabout and requires maintenance of the drop checker solution. I have been toying with the idea of a DIY NDIR sensor, but sources and filters for 4.26um are a bit pricey.

Hmm, looks like these guys have it figured out, though. And $65 isn't bad:
http://www.co2meter.com/collections/...pwm-co2-sensor
Unfortunately it's only got a repeatability of +/- 40 ppm. I think the biggest problem is that no-one is building sensors for planted tanks, they're all for air quality measurements and need a range of thousands of ppm. We need one with a range of 100ppm and an accuracy of 1ppm. That's less than 7 bits, should be easy right?

Looks like I'll have to stick with the drop checker solution for now. It really is amazing to think that drop checkers can measure that accurately. 30ppm is .003%. A lot of the expensive commercial sensors can only hit .1% resolution.
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Old 02-13-2011, 07:27 PM   #19
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They actually do make underwater co2 sensors
http://www.contros.eu/products-hydroC-CO2.html

or something like it.. It's beaucoup bucks though. I remember plaintbrain used it in his experiments.

The only problem with using a color sensor looking at a drop checker is that the pH solution loses its property over time so you'd have to put in a new solution every few days.


** just read the specs on that sensor. It uses IR absorption spectrometry.. oooohh.
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Old 02-21-2011, 12:19 AM   #20
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Progress!

After a few tries, I got the lights built:




The LEDs on the black stars are 5W from DealExtreme and the red ones are Luxeon Rebels from Sparkfun. Both are driven with a board from DealExtreme that I modified to provide 700mA.

LED--------------Voltage(V)----Current(A)----Power(W)
DealExtreme(x2)----13.1-----------.71-----------9.3
Sparkfun------------3.2-----------.71------------2.3


So I borrowed the light meter from work and decided to take a few measurements. I divided the bottom of the tank into 12 sections and took readings with the left, right, center LEDs, then one more with all LEDs on. The measurement head is sitting on an aluminum heatsink to simulate substrate depth.

Heres the Data in a Google Doc.

Using Hoppy's conversion of 70 lux/umol for LEDs I converted the lux readings to PAR and made a few charts:





I am a little disappointed that I am only getting 60umol with this setup. I have another of the 5W LEDs. It looks like I am getting about 20umol per LED with these so if I can get another wired up, I might be able to bring it up to 80umol. Hopefully this will be enough to grow a nice short carpet of HC.

On another note, I visited a different LFS here in town (AquaWorkz) who carries some planted tank supplies and picked up a bag of Fluval Stratum for Shrimp because I hear it is finer grained than the one for plants. It looks pretty good, but I may wait to see if anyone else has luck with HC in this substrate. They also had the 88g Fluval CO2 setup that I want to use.
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Old 02-21-2011, 05:07 PM   #21
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This is so cool
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Old 02-22-2011, 07:45 PM   #22
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Why don't you just do everything with an arduino unit? They have shields for everything these days. You can control stuf via timers, sensors, and relays.

This guy makes shields for controlling his marine tank

http://www.practicalmaker.com/projec...ium-controller

I currently use an arduino along with a few simple components to dim my lights from 10% to 100% using a 10 turn potentialmeter. I plan on using a DS1307 to dim the lights on a timer to create a dawn to dusk effect





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Old 02-23-2011, 05:06 AM   #23
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Quote:
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Why don't you just do everything with an arduino unit?
Arduino's are fine, but I don't happen to have one. I do have a dozen ATMega128's laying around. Also, I do embedded electronics for a living and as a hobby, so if I am going to DIY I might as well build the electronics from scratch. I am mining the germanium right now.* Well maybe not, but I have a garage full of surplus electronics that I want to put to as much use as possible.**

I actually started the electronics yesterday. I am using an ATMega128 on a breakout board from Sparkfun, a WiFly 802.11 module (yes, my nano tank will have a web page) and possibly a 128x128 OLED display.

I finished up the power supply board tonight. I needed at least 3.2V for one set of LED's, 13.3V for the other set, 3.3V for the digital circuitry and WiFi, 5V for the LED cooling fan and 12V for the pump. I ended up with 20V for all of the LEDs (the switch mode driver will have no problem with the extra voltage). I put in a 12V switcher with an enable line for the pump so I can turn it on and off easily. I then added a 5V switcher for the fan and a 3.3V linear off of the 5V for the digital circuitry.

Hopefully I can wire up the processor tomorrow night and have the LEDs dimming by the weekend (The drivers have an enable pin that can be used for dimming). My goal for the weekend is to install a bootloader that works over the WiFly module so I don't have to connect my computer to reprogram.

------------------------------------------

*If you wish to make an apple pie from scratch, you must first invent the universe - Carl Sagan
http://www.youtube.com/watch?v=zSgiXGELjbc

**That reminds me; anyone use PIC chips? I discovered several in the garage last night that I would like to find a good home for.
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Old 02-23-2011, 10:05 AM   #24
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Dude that sounds awesome please post the step by step if you can. Does your driver dim by PWM? if so is it 5v or 10v?

The damn meanwell 60p dims by 10v PWM so it was a pain in the ass trying to convert a 5v pwm from the arduino to 10v for the driver. Also are you going to add a RTC clock to it?
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Old 02-25-2011, 12:48 AM   #25
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Quote:
Originally Posted by Im2Nelson4u View Post
Dude that sounds awesome please post the step by step if you can. Does your driver dim by PWM? if so is it 5v or 10v?
I'll do my best to keep the updates coming. It's always a balancing act of build vs. document...

The driver boards are from DealExtreme and are rated 5W up to 18V input. The driver IC has the part number scratched off, but a few comments around the web have identified it as an AX2002 from Axelite. It has an enable input that can modulate the 330khz main oscillator from 0 to 100% duty cycle. The enable line is a logic level input, <0.8 or >2.0V. I plan to drive it with one of the 3.3V PWM outputs from the ATMega128. The biggest downside of this driver is that it requires a pretty hefty DC power supply, but if you are working with an Arduino, you probably already have some sort of DC laying around.
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Old 02-26-2011, 01:56 AM   #26
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I don't know if anyone else finds this kind of thing interesting, but I put together a communication protocol for this thing. The protocol implies an underlying control model which I think is pretty nifty if I do say so myself
https://docs.google.com/document/d/1...thkey=CLmgqdMG

Summary: I/O is defined as "channels" and "events" can be setup based on timers or inputs to "trigger" outputs to go to a certain level.

For instance event 2 can be set up to occur when the temperature (channel 3) is 76. Trigger 4 can then be kicked off by event 2 to set the heater (channel 7) to 50. Trigger 5 can also be kicked off by event 2 to set the yellow LED (channel 1) to 100.

Offset events can be linked so that event 4 occurs 9 minutes and 40 seconds after event 3 which occurs 20 seconds after event 4. Then one trigger turns the CO2 on at event 4 and another trigger will turn the CO2 off at event 3. Bam, the CO2 is now going to be turned on for 20 seconds every 10 minutes.

Does that make any sense?

Gotta run to go grab some chinese food, but look the protocol over if you like and let me know what you think, since it's likely the protocol I'll use for the peristaltic pump controller.

Oh, BTW! I bought a Clippard Mouse solenoid from Over_Stocked, so I am planning to run pressurized CO2 as described above.
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Old 02-26-2011, 02:34 AM   #27
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I2C?

I have my CO2 run for 2:40 then shuts off and turns on again for 2:40. I adjust the time for CO2 concentration instead of the needle valve. It's go much easier.


gotta go make some pancakes.
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Old 02-26-2011, 04:15 AM   #28
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Quote:
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I2C?
As in Inter-Integrated Circuit? Only if I have to. I've never liked I2C, preferring SPI. I plan to use an SPI RTC, probably a DS1305 since I think I have a few samples laying around.

I also don't like Dallas One-Wire, but I have several DS18B20s laying around, so I'll probably use them to measure water and LED heatsink temp.

Quote:
Originally Posted by mistergreen View Post
I have my CO2 run for 2:40 then shuts off and turns on again for 2:40. I adjust the time for CO2 concentration instead of the needle valve. It's go much easier.
Great, so I'm not crazy. Or we both are...

That reminds me I have a few questions.

1. Does the 20g Fluval CO2 kit have a real regulator or is it just a needle valve? If it's a needle valve and I connect the output to a solenoid, it'll go up to full pressure. BOOM! I'll probably go with the 88g kit, but wanted to keep my options open because I don't have a lot of room, especially if I want to fit 3 peristaltic pumps in there...

2. If I put the diffuser (I plan to get the new GLA diffuser, so I hope he doesn't mind the image) in the filter like so:

That look like it will work?

3. Most importantly, I am thinking of a getting a Marineland Stealth 50W heater. Can I put it in the filter area too? Will I need to keep it from touching any of my bio-stars or filter foam? Can I put it sideways? I REALLY don't want anything in the main portion of the tank; I don't even like the acrylic spraybar.
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Old 02-26-2011, 04:47 AM   #29
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Very cool. Similar to my plans. I've got a little embedded experience and I'm just now really getting into communications (wanting to do 802.11 too). I'll be watching this one while I'm waiting/prototyping.

How do you plan to waterproof your DS18B20?
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Old 02-26-2011, 05:01 AM   #30
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1. They look like a combo regulator & needle valve. the 88 come with a bubble counter which is important to have.
2. They come with diffusers so you might not need the GLA diffuser. yeah, it should work in the filter.
3. How big is this tank? 2-3Gallons? 50W is a bit much. 10-15W should be perfect and smaller. From touching a heater while it's on, I'd say it's on around 150F - 200F. If plastic doesn't melt that that temperature, it should be fine.

ps. You can make your own heater too like radiant floor heating or a heating blanket.
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