Here is the schematic:

The board is entirely SMD components and is about 38mm by 31mm. Unfortunately the main IC is available in 10-eMSOP package only, which isn’t the easiest to hand solder, but I have a video at the bottom that shows one way of soldering it.

The latest version of the board looks like this:

And in 3D:

The BOM is for 12 LEDs (48V input) with max 1A current:

LM3409HV

BOM LibreOffice
BOM Excel

For different combinations of current and LEDs there are a few things that need to be computed which you can find about in the data sheet:
LM3409.pdf

For PWM dimming, R4, R6, R7 and C6 need to be left unpopulated. Also the middle two pins of the 4 pin header need to be shorted.
For analog dimming, all components are required and the outer two pairs of pins need to be shorted on the 4 pin header.

All this is under the Creative Commons Attribution-NonCommercial-ShareAlike 3.0 license and all files can be found in this archive:
LM3409HV0.3.zip

Here are a few photos and video of the driver:

And this is a time-lapse of me populating a board. I’m not an expert, but I’m good enough. Flux and thin solder make life easy when you deal with SMD components!

I’ve added a 12bit i2c DAC on the board that allows for nice 4000+ step analog control. I’ve also changed the PFET to a TO-220 package and added a space for a monster heatsink. I also had to add a comparator circuit to switch off the LEDs when the control voltage is at the bottom since the LM3409HV doesn’t shut off even if the Iadj pin is grounded.

About I2C dac:
There were really only a couple of options for a DAC choice. MCP4725 and MCP4726. The two are basically the same DAC, but one has external addressing, while the other has external reference voltage. In general, either chip will work with the board, however with the MCP4725 you need to set the last address bit via the smd jumper.

Addressing:
Both chips use 1100 for first 4 bits + 3 additional configurable pins.
On the MCP4725, you have 4 options when you order 110000X, 110001X 110010X and 110011X where X is set to either 0 or 1 via the external smd jumper.
The MCP4726 doesn’t have external configurable pin, so there are 8 available options from Microchip. However I was able to find only the first 4.

What does all this mean?
It means that with current availability, you can put 8 drivers with MCP4725 or 4 drivers with MCP4726 on a single i2c bus.

Now if you don’t need more than 4 drivers per bus, the MCP4726 can give you one extra feature: external maximum override via potentiometer. Basically you can use the 3 pin jumper to wire a potentiometer and you’re effectively using that potentiometer to set the maximum control voltage that will go to the driver.

Programming:
Since this is now i2c and not just a PWM, you can’t just digitalWrite(LEDPIN, 255); Howerver it is not very hard to talk to the DAC. It takes 4 bytes:
1 byte – address
2 byte – commands
3 and 4 byte – registers of the 12 bits (last 4 bits are ignored)

I’ll probably have a library for it sometime in the near future.

As always, open source and all files can be found here:
BOM, Schematic and other files here

Enjoy

And here are a few shots at it:

Quick check on newegg showed that I’ll have to spend at least $350 to get a decent NAS solution. I also looked at the development of ZFS – Sun’s latest and greatest filesystem. It turned out that ZFS is very nice for home NAS solutions that give you features of commercial products like NetApp.

Second check on newegg for cheap Atom PCs showed that I can put together a PC for less than $350, which would work for ZFS.

Before I got the hardware, however, I decided to do some more reading on the forums of who’s buying what, what works and what doesn’t and in general to educate myself a bit more on the ZFS NAS topic. HardForum was very useful place for that. As I was reading, I realized that an Atom computer might be a bit underpowered for a ZFS NAS box, but because I wanted low power solutions, I didn’t have too much choices.

Fortunately for me, only few months ago, Intel had released their SandyBridge cpus and specifically the low power i3 model with 35W TDP, which for a powerful CPU is pretty good. From there I settled on a system based on the i3-2100T CPU and started looking for motherboard. Initially I was considering an Asus one, but the folks at HardForum convinced me that for the same price I could do a proper server setup so I ended up with a SuperMicro X9SCA-F MB which supports ECC memory, IPMI, KVM over IP, has a video card and two excellent GBE Intel NICs. I added 8GB of ECC memory, a good PSU (Antec Neo Eco) and one IBM ServeRAID-BR10i SAS/SATA controller for extra 8 SATA ports and I was all set to support up to 14 hard drives . All this I stuffed in a Norco RPC-250 2U rack chassis. Only downside is that it holds only 9 drives, but that’s more than I’d need in near future (I think) .

So after the server was all set, it was time to select a the hard drives. I ended up getting 6 Hitachi 5k3000 2TB drives and to my benefit, newegg kept offering them with rebates and instant discounts, I I got some nice deals on them.

The drives are configured in raidz2 (RAID-6 equivalent with ZFS) to give me a little over 7TB useable space.

For OS I picked OpenIndiana (OpenSolaris fork after Oracle bought Sun and ditched it). In a few words I’m very happy with it and very pleasantly surprised of the ZFS features and tricks you can do. So impressed, in fact, that I’m wondering how come it has not become the standard filesystem of choice for every hacker or technical user and OS like Linux.

As far as speed goes, I get about 90MB/s over the GBe, which is faster than my previous USB2 drives. Local speeds are 371.69 MB/s Write and 474.07 MB/s Read average of a 20GB file with dd. From power usage stand point, the system uses 65W with all 7 drives spinning (compared to 280W for my desktop) when idle and about 85-90 under load.

Soon, I’ll write about setting up the DLNA and NFS servers, as well as the napp-it web interface.

After I moved all the data, however, I realized how slow is our WiFi. I was barely getting 14MBit/s on a 54MBit connection. It turned out that my wrt54g was not able to handle it (cpu wise).

So I figured I’d spend some $ on a new router, making sure that its CPU is fast enough to handle the traffic and that supported either DD-WRT or Tomato firmwares. After some reading I settled on the Asus RT-N16, which is almost like a small computer with wifi and a built-in gigabit switch.

First, I tried DD-WRT. The installation process was quite painless. Just followed the wiki on the DD-WRT web site. In about 10 minutes I had a working 802.11n WiFi under the latest dd-wrt firmware. So I connected with the laptop to run a speed test and I got 600KB/s! I changed the settings to 802.11n only wifi – no change. I tried all kinds of combinations of channels, encryption settings, radio settings, but the best I could get was around 1.2MB/s while the laptop was showing a 130MBit/s link.

Little before I was ready to return the router I decided to give TomatoUSB a try. Installation, again, was quite fast and easy and 10 minutes worth of setting up I had an identical 802.11n WiFi. I started a file copy over the network and was pleasantly surprised. The average speed got to 6.5MB/s with peaks at 7.2MB/s. In theory that is still less than half the 130MBit/s link but for WiFi that’s pretty good. Also, the laptop is limiting the connection to 130MBit/s, otherwise the router supports a 300MBit/s link.

The moral of the story is, that one should try different software solutions before giving up on the hardware.

It took about 10 minutes to cook and the fish tasted great. If the keep stocking it (it said on the label it comes from Greece), I’m sure it will become a frequent item on our menu

I also have the controller up and running. Initially it started monitoring pH only and wasn’t logging the data. Then I added a few temperature probes. Then came the programming of the network controller and I added a small program that saves the data to a database and uses Google’s Web Toolkit to visualize it:

http://reef.geodar.com/

As you can see it is fairly taxing on the browser and even though I like how it looks, I wasn’t very happy with it. A few days ago, however, I found out about ThingSpeak, which does roughly the same thing, but it is much more polished than what I had written. It also uses a much lighter library for charting – Highchart – so it is much easier on the browser.
So I quickly sat down and fixed up the code for the controller to talk to ThingSpeak and I put together a quick graph:
[iframe_loader src="https://thingspeak.com/channels/445/charts/1?height=220&width=450&round=2&average=60&timescale=1&days=2&bgcolor=%000000&yaxis=pH&xaxis=%20&title=pH" ]
[iframe_loader src="https://thingspeak.com/channels/445/charts/2?round=2&average=60&days=2&bgcolor=000000&yaxis=%CB%9AC&xaxis=%20&title=Room Temperature" ]
[iframe_loader src="https://thingspeak.com/channels/445/charts/4?round=2&average=60&days=2&bgcolor=000000&yaxis=%CB%9AC&xaxis=%20&title=Display Tank" ]

So now I’m playing around with their API more over here:

http://reef.geodar.com/charts.html

For a few months now, I’ve also been removing my sandbend so that I can replace it with a coarser one. The super fine sand just gets blown too easily and it I don’t like that. Now it looks pretty good and I’m sandstorm free:

Last week, I finally put my dosers for calcium and Alk because I grew tired of manually dosing every night. And since I have a controller I modded the dosers a bit with a simple relay so I can directly start and stop them:

I put them on the 2×4 in the ceiling of the cabinet. Very good place in my opinion:

I’m also glad I left some space on the side of the sump. Otherwise I don’t know where I could have put these solution jugs:

So for one week now, I’ve been doing Ca and Alk tests twice a day at 8:30 so that I can adjust the dosage properly. On the first day I noticed that something was wrong and first looked at the code of the controller. Of course it was a little messed up . I fixed it and set the calcium to 47.6ml and the soda to 58ml (Alk is a little low so I want to bring it slowly up). Here are the results:

I use two tests for Alk so that I can verify what is happening. As you can see the Salifert test had some strange readings at one point (I repeated the test every time I noticed an anomaly just to make sure I’m not making a mistake in testing) compared to the Hanna digital checker. Also, both are showing somewhat different value (though with almost constant difference). Which one is the correct value is arguable, but I don’t care much. After I get it to the level I’ve decided, I’m just going to care about the stability.

Calcium still hang below 400, so I’ll probably increase the dose a bit to get it to 450 and keep it there.

When I talked abut the controller earlier, I forgot to mention that I’m working on a box for it. This weekend came my last connectors so I mounted them and did some internal wiring:

Now I wonder whether I should wire out the rest of the pins to something like a DB25, but I’ll probably leave it as it is for now. All I have do to now is make a little hole for the IR RCVR and paint the box and it should be all set.

Finally, I am in the process of setting up a continuous water changing system, but enough for this post. I’ll write more about this in the next few days. My new salt is coming on Tuesday so I’ll probably turn it on for the first time on Wednesday. Keep your fingers crossed

So as I was reading about that club, it turned out their forest is open only for club members and nobody else. Only once a month – last Sunday of the month – doors open to the public. Of course I gave it a shot . And of course I liked it . The next step was to educate myself a little more on the subject so that I could decide if it was really for me. I bought Shooting the Stickbow and started reading.

Basically, there are two types of bows: compounds and traditional. The former are pretty sophisticated technology making use of various alloys for the bow itself, special pulleys and cam systems, which facilitate pulling but give much more power the arrow, have fancy sights, triggers and what not – complicated stuff. Traditional are exactly that – traditional. In its most elementary form, we have a slightly curved stick with a rope on it and that’s it.

I liked the traditional part better and it is a little cheaper because there is no piles of gadgets that you need to get for your compound. Of course, you can spend insane money for most things and traditional bows are no exception, but I’m not such a fan. So for 119 bucks I got a Samick Sage take down bow, which IMHO is great. I also got a dozen of arrows and a handful of other small things like arrow rest and finger tab and I was ready to go shootin’:

I will not go into much detail but let’s say that the the aforementioned book helped me a lot because it turned out you can’t just buy any arrows for any bow. The lenght, material, thickness, spine (bending), fletching material all matter.

So far I’ve gone several times to shoot, and even became a member of the club – Cos Cob Archers. Generally I go every weekend, but this one was raining all the time so I couldn’t go…

I have to say that so far I really enjoy shooting. Let’s see how it goes.

But before I can fly a real RC plane, I decided to practice a bit on a simulator to get familiar with the directions when the plane is coming toward me or flying away. I took some cheap PC controller for 20 bucks and I started “flying”. It was a lot of fun . After several sessions it looked like I’d enjoy doing that, and I was also looking for a hobby that will take me outside more, because all my current hobbies are indoors.

So, on the same site, I followed the for sale forums soon I got a mint condition ParkZone T-28 “Trojan” (not my photo):

Then I paired it with a Spectrum DX6i transmitter:

And like a curse, since then (November) until now there hasn’t been a single warm weekend without wind so I’m yet to take it out and give a try! Damn winter!

That’s about it so far. I’m waiting for spring and summer to come, meanwhile I start the simmulator every once in a while to get a few minutes of airtime .

More about RC stuff when the weather gets better and I do my first real flight

Overall, I have noticed that personal blogging has decreased probably because of social sites like Facebook. I’m firmly decided that I will not make an account there. Therefore I will try to resurrect this little habit of blogging.

Problem is that if I try to make up for past months, I’ll drag it to till next year. So I would write a post about the main themes that have happened. Let’s see what happens.

When I saw the first Kindle I was quite disappointed how ugly it was, not to mention the price. On the other hand I was happy that a company like Amazon has decided to invest in that kind of technology. So three versions later, about a month ago, they now have their latest Kindle. A few of the key features are: 1 month battery life (e-ink screens use battery only to print the screen once). The screen is reflective (as with all e-ink screens), which makes it perfect for reading in bright lights (the proper way of reading), although you can’t read in the dark. The refresh of the screen is about a second, which is a whole different story from what it was few years ago. PDF support is also quite good and fast. The price is less of that on an iPod nano, and it finally looks nice.

So, I decided to spring for one of ‘em Kindles. Currently they sell two versions. One with WiFi and one with WiFi + 3G, which means it has internet everywhere you have GSM signal with AT&T. Why internet on a Kindle? Well the reason is that there is a webkit based browser on it, which can be used to read articles and check email. Of course the e-ink technology at the moment is black and white and can’t be compared with a nice color screen, but the point is you have wikipedia in your pocked everywhere you go FOR FREE! Yes, Internet on the 3G Kindle is free (at least for now). Also the browser has a so called Article Mode, in which it strips all crap from the web page and converts the main article to a book, so that you can read it like a book on your kindle.

I’ve been using the deice for about two weeks now and I’m pretty happy with it, keeping in mind what it is meant to be. Reading is like reading from a book. There is no straining of the eyes, that you get when you read from a monitor (although I stare at a monitor almost 18 hours a day so my eyes are trained by now ). I’m finishing now Brief History of Time by Stephen Hawking. The book is pretty good, but more about that when I finish it.

In addition to reading books, I use my Kindle for reading news. With a little help from Calibre, every morning I download the news from a few websites and I put them on the Kindle. After I’ve set up the news sourced, all I have to do is … nothing. As long as Calibre is running, and the kindle’s wifi is on, my news arrive wirelessto my Kindle every morning via Amazon’s Whispernet. I have to say that I’m very pleased with how well all this works. I think Amazon has really put some effort in it.

Another thing I really enjoy is that while I read, if I move the cursor net to a word, I get a short excerpt from the built-in dictionary. Very useful for people like me, who sometimes see a word that can’t exactly translate on its now.

Of course, chitanka.info is a huge library of Bulgarian and translated in Bulgarian books. The latest Kindle has no trouble rendering Cyrillic (unlike its predecessors). I have to say, that living outside Bulgaria (even with plenty of Bulgarians around) is having impact on my native vocabulary and reading a few books in my mother language will do me well.

pics

Well, Starter is on BG Radio, which means it is time for me to go to bed…