Power supply using a 2U rack chassis (56K warning)

[hak8or]

Post on my website: http://hak8or.com/

I saw a post about using magnetic fields on the human brain to get certain reactions, and the first thing that popped to my head was trying it out myself.
http://hackaday.com/2011/08/15/controlling-muscles-with-high-intensity-magnetic-pulses/

So, I started to get my old capacitor bank up and running again, which is basically 3 X 7 200V capacitors. I forgot the capacitance on each, but I think it was 2200 uF. Then I realized that I needed a high voltage source. I was about to go make a voltage multiplier for getting Mains to a high enough voltage for the bank, but I finally came to the conclusion that I should make a proper voltage source. So I took one my old finds, a video scale thing. It has a large amount of FPGA's but after a while of thinking I found that I would have no use for such a FPGA based unit, so I took out the boards and started working on the power supply. I did off course save the boards in case they would ever come in handy for something else. :P

Here is how the unit looks.

http://8486.a.hostable.me/pictures/Power_supply_BIG/P1250084.JPG

http://8486.a.hostable.me/pictures/Power_supply_BIG/P1250086.JPG

Here is what the inside of it looks like. There was another board ontop that also had more FPGA's, but I took it out a long time ago to try to get access to the JTAG pins. It is rather heavy, and I will tell you why later. I will say now though, it was a major surprise!

http://8486.a.hostable.me/pictures/Power_supply_BIG/P1250087.JPG

Here it is without the PCB inside. It has a power supply which gives me -10v, -5v, gnd, +5v, and +10v. I am going to keep that board inside the unit for powering the digital circuitry, since I suppose it should give a nice clean +5v with ample current, for running all those FPGA's. I need to check it on my scope with a dummy load sooner or later. Sorry for the dark picture. For all my pictures I have been using a point and shoot (DMC-TZ3) and trying to not use flash at all. So far, none of my pictures have used flash! That gives me the macro shots of the boards without the horrendous flash blaze. A tripod is essential. :P

http://8486.a.hostable.me/pictures/Power_supply_BIG/P1250091.JPG

While working on the front of the unit, I wanted to see about drilling holes and a slot for another display, a few buttons, and a few more leds. The chassis itself is spot welded together. The front panel itself was rather heavy after I took it off the rest of the unit, and here is why.

http://8486.a.hostable.me/pictures/Power_supply_BIG/P1250092.JPG

Wait for it ....

http://8486.a.hostable.me/pictures/Power_supply_BIG/P1250093.JPG

Holy .. !! It is a solid metal slab, an entire 3/4 of an inch of metal! I am guessing they used laser cutters for it, or something like that, because there is no way on earth I will be able to drill through that with a drill. I am now working on what MCU to use, how to set up a front panel with it (Planning on using a VGA monitor), where to get the connectors for different voltages, and what I want from this unit. Things like that. All my attention will be currently dedicated to this for now. Once I get a satisfying result from this, I will continue working with the little robot thing a ma bob, and then on a desk light using a LCD with CCFL tubes I found a long time ago.

Any comments are welcome! Thanks for reading :)

[hak8or]

I added in quite a bit of stuff, mainly the high voltage section of it. The reason it took so long for so little progress was because I have to work with what I have. I don't have much hardware tools, so it is very difficult and slow. :P

First, as always, pictures!
I started to think about the layout of components in the chassis, what I will want where, things like that. I decided that I will want a high voltage source from this (MOT, only 2 kV or so), which is also capable of reasonable current. Using a MOT with another MOT with a shorted secondary gives me enough impedance (?) to prevent the breakers from blowing. Problem is that it increases weight by a LOT. Each MOT weighs 20 or so pounds as a quick guess. I won't be moving this that often, so it is not a that much of a problem.

http://8486.a.hostable.me/pictures/Power_supply_BIG/P1250100.JPG
As you can see in the above picture, there are a few noticeable components. The white cylinder at the top is a 15V cap, I forgot the capacitance but I think it was 68,000 uF. I will use that as a power source while the unit is shut down for the internal logic, such as a pic24F and the propeller. It should last a very long time with the PIC in the lowest power state and the propeller shut down, but I have yet to do the math and find out what the current usage will be in certain scenarios.

The PCB with components on the right is the psu that came with the original unit. It is a switching power supply, so I am hoping that it is efficient, more efficient than a mediocre transformer, as well as supplying a clean 5 volts. I will use that to drive the logic.

On the left, there is a MOT (Microwave Oven Transformer). These guys supply supply about 2,100 volts with a short circuit current of 16.5 amps usually. That is an excellent very high power high voltage power supply, but extremely dangerous. Only use these if you understand high voltage and all of the dangers/safety associated with it. If it does short with you in the circuit, you are most definitely dead. I will use this as a source of high voltage at high current for all my capacitor bank experiments. Charging them for a future TMS project I intend to do is one of the applications.

Under that is a small transformer that accepts 120v or 240v and sends out 20 and 12 volts, if I am not mistaken. I am going to use this transformer to power a few LM317's or other adjustable voltage regulators I find. This way the power sources that I get from this unit will not use up current from the switching power supply, so I can use a lot more current.

In the middle I have a perf board from radioshack. They are horrible, if you try to re solder a hole even twice, the copper layer just falls off, but they are all I have right now, so I will make due with what I have. I will use this board to hold the PIC24 and the propeller, as well as a few Fet's, transistors, and support circuitry.

The random gray ribbon cable is for a VGA connector in the back, that will be attached to the propeller. The VG will be used for a monitor to display voltages and current usage of each voltage output, things like that. Phew, that was a lot of text for only one picture! :P

This is what I will use for high voltage cable in the unit. I am fearful that the tape will not provide enough insulation from the high voltage, so in later pictures cover the wire with plastic tubing. At the end there is heatshrink tubing, which I later will shrink around the connector to the high voltage transformer. The core I got from some TV or something, I don't remember.

http://8486.a.hostable.me/pictures/Power_supply_BIG/P1250103.JPG

I was considering using component cables because they seem to have good connectors, but after looking close up at it I realized that I do not think the connector will be able to handle 2 kV.

http://8486.a.hostable.me/pictures/Power_supply_BIG/P1250105.JPG

In this picture you can see that I added in a MOT to provide ballast so no breaker will pop when the transformer is being used. It will basically act as a current limiter for high voltage which would allow at most 7 or so amps at 120 volts. This will give me 400 mA at 2100 V (840 watts). The tubing and insulation for the high voltage source is now seen. I used a thick plastic tube used for water as the main insulator to prevent the high voltage wire from touching the metal chassis.

http://8486.a.hostable.me/pictures/Power_supply_BIG/P1250107.JPG

Here is the completed high voltage cable and probe. For the connection end I used a multi meter probe. I aim to have the possibility of using a flyback to generate an even higher voltage (40+kV), hence all the worry about insulation. Granted, the multi meter probe is rated for only 1kV, I am going to use proper gloves anyways during this, so not much worry there. I will have a holder for the probe when not in use, which will prevent arcing to something else if I accidentally enable it when I did not intend to.

http://8486.a.hostable.me/pictures/Power_supply_BIG/P1250109.JPG


I still have a LOT to do. I need to start working on the digital work, as well as finish the mains wiring in the unit, specifically finish working on the relays to enable/disable the main transformer and high voltage transformer. I expect to have that done by tomorrow, and start working on the digital parts of it.

I also started working on my website. I aim to have the website nice and simple, but I know absalutly nothing about HTML or flash or javascript. I wanted to make my own little gallery thing that links to the forum thread and full res pictures relevant to the selected picture, but that turned out a bit too complicated for myself. So instead, I found a template gallery and took out things that I did not want and changed stuff around. Here is what I have so far. As you can see I have a long way to go still. :P
http://8486.a.hostable.me/

Thanks for being able to get through this long forum post, congratulations for making it through this boring post! :P

[ian]

Nice build log, and great pictures! I'll post this up.

[bearmos]

really interesting project, hack80r! looking forward to seeing the progression.

I also started working on my website. I aim to have the website nice and simple, but I know absalutly nothing about HTML or flash or javascript. I wanted to make my own little gallery thing that links to the forum thread and full res pictures relevant to the selected picture, but that turned out a bit too complicated for myself

WRT galleries - i'm currently experimenting with a CMS called joomla (php and mySQL required), along with a gallery plugin called sigplus. the cool part about sigplus is that you can make galleries really quickly -and they look really nice, too. for comments, you simply include a text file properly formatted which places the images in the correct order and simply incldues filenames, titles, and comments - it's really simple and fast.

depending on what host you have, joomla can be offered as a one click install that makes things pretty easy. i've found that joomla has quite a bit of a learning curve - most people prefer wordpress, but that's the only thing i have experience with. like you, i have very little html, CSS, php experience (i'm an embedded guy)

. . .didn't mean to hijack your build thread - just wanted to share some information

[bearmos]

btw, do you comment on HAD? the alias looks familiar.

[hak8or]

Nice build log, and great pictures! I'll post this up.

Thank you Ian. :D And thanks for moving this to project logs as well.

really interesting project, hack80r! looking forward to seeing the progression.

I also started working on my website. I aim to have the website nice and simple, but I know absalutly nothing about HTML or flash or javascript. I wanted to make my own little gallery thing that links to the forum thread and full res pictures relevant to the selected picture, but that turned out a bit too complicated for myself

WRT galleries - i'm currently experimenting with a CMS called joomla (php and mySQL required), along with a gallery plugin called sigplus. the cool part about sigplus is that you can make galleries really quickly -and they look really nice, too. for comments, you simply include a text file properly formatted which places the images in the correct order and simply incldues filenames, titles, and comments - it's really simple and fast.

depending on what host you have, joomla can be offered as a one click install that makes things pretty easy. i've found that joomla has quite a bit of a learning curve - most people prefer wordpress, but that's the only thing i have experience with. like you, i have very little html, CSS, php experience (i'm an embedded guy)

. . .didn't mean to hijack your build thread - just wanted to share some information

Thank you for the links and information to joomla and CMS! I was looking at the demo's and while it is rather cool looking, I have already found one of the galleries on my own old website. I am going to be using http://simpleviewer.net/products/ for the photo galleries themselves. I don't really need to write much up, since I am linking to the forum, where I am going to be doing the write ups anyways, and I already have experience with this so I can jump on it without too much problems and head scratching. Thank you very much for the information on joomla and CMS, I will most definitely check it out more in detail later when I will want to change or add some more stuff to the website. Don't worry about "hijacking" it, more information is always a good thing. :)

btw, do you comment on HAD? the alias looks familiar.

Yep, on hackaday I am Someonecool and hak8or as well. I have a few build logs there too, but their forum seems dead right now. I originally wanted to post my stuff on there to help get the forum going with some new posts, but it did not work that well so I ended up posting on here. Needless to say, thanks to Ian's generosity with front page space, my projects sometimes get put on the front page, which leads to much more people seeing them. My last post was about the TMS machine from the guy that had a electromagnet on his head which led to twitches and stuff.
http://hackaday.com/2011/08/15/controlling-muscles-with-high-intensity-magnetic-pulses/#comment-435584 <-- there am I.

[hak8or]

So, yesterday I was unable to do too much, but today I had more time.

I continued working on the wiring, specifically the high voltage (mains) wiring. Then I continued think how to do the digital aspect of this. I am going to have voltage sensing on the one or two adjustable voltage regulators, as well as the 3v3, 5v, and 12v line. I am aiming to have an update rate of maybe once or twice for voltage sensing, which will be easily satisfied using the ADC on the PIC. Next comes the current sensing, which is more problematic. I originally wanted to have enough bandwidth for current sensing for a MCU, so I can tell what is going on for each clock cycle, but with most simple MCU's reaching 40+ MHZ that would mean that I need at least 200 MSPS for one voltage line (3v3 or 5v), which is far far out of my capabilities. So instead I ended up with each current measurement at 1 MSPS at least, that gives me 200 KHZ of bandwidth which is enough I guess for my needs.

Each line will have current measurement at least at 1 MSPS, and I plan on having five lines (3v3, 5v, 12v, and two adjustable) which means I need 5 MSPS at the very least. That means that I will have to use an external ADC, problem is that I cannot find any cheap DIP adc's, so I will maybe have to conjure something up myself later. I am working a few other things out, even considering getting another propeller instead of a PIC since the propeller has 8 separate cogs, each capable of 10 MIPS, which should handle any ADC I throw at it within reason.

I also need to purchase some current shunts, since I only have one at home right now. If I am going to buy current shunts online from mouser, I might as well buy a few other things. I am mainly looking at the PIC24HJ12GP202 since it is so cheap and can do 40 MIPS, not to mention it being a DIP package. It does not have much program flash and ram, but for the price it does not seem too bad, if anyone has any other suggestions please do tell!

That is how far I have come so far, I am mostly working out and planning the digital logic behind it, of which there is a lot. I still have to work out the propeller generating a VGA signal to a monitor for displaying the current usage and voltages, things like that. I will want to be able to plug in a keyboard so I can control scales and things like that for the measurements, not to mention I can get something like PONG running on the propeller. A power supply that can play pong, that is something I never heard of. :P

Thank you megabug, shadyman, and GeekDoc for pointing out that it is a 2U chassis instead of 1U ! :D

[hak8or]

it is the weekend, so I am working on buying some parts. I have till Sunday night to order so I am taking my time. There are no DIP adc's higher than 1 MSPS, so I am working on doing some makeshift SMD to dip thing to use the higher speed adc's. I am also working out if the propeller can handle the bandwidth of four 1 ADC's.

Turns out that I can get pretty fast ADC's that are SMD for very cheap, upwards of 40 MSPS, so I am working out how I can use a propeller chip with it. It might turn out that I can use just the propeller chip, and not bother with using a PIC at all, though polling might turn a bit problematic. Still working it out though. So yeah, this project is still ongoing, even though not much has happened lately!

[hak8or]

Hello everyone!

I have finally found what ADC to use! It is very cheap, parallel out put, it does not have the reference high and reference low things from other ADC;s, it is in a easy to manage chip package, and best of all it seems simple to use.
http://search.digikey.com/scripts/DkSea ... BRSZ-50-ND
There are a lot of moderate speed ADC's that use SPI, but there are no hobbyist friendly MCU's that are capable of 40+ MHz SPI ports that I am aware of. There are no DIP ADC's that are capable of more than 1 MSPS for under a $40 or so dollars. Basically, if you want a high speed ADC (more than 1 MSPS), you will have to go SMD for a few reasons. One, because there simply are no reasonable cost DIP adc's of such speed, manageable interface (Parallel), and within a reasonable price range.

So, to use that ADC I will need to have the usual decoupling caps, and wiring it up using magnet wire would prove too tedious for me right now, and I want to FINALLY make my own PCB's, so I am focusing on how to make a PCB myself. I do not have a laser printer, so the most common technique of toner transfer is out. There are a few methods that remain for me. Photo resist, which seems awesome but then I will have to purchase the layer that is sensitive to light online, and then laminate it myself, and I do not have a lamination machine. I will therefore have to purchase the boards with the layer already on them, and the only source of that is online, and from what I have seen they are not as cheap. Plus, I will have to make a UV exposure box, or have to mess with exposing it myself using a light bulb.

Then comes printing directly onto the copper clad using my inkjet with special ink, and then etching away. That is also problematic, because I cannot change the ink in the ink cartridges, since I have a Lexmark which is HORRIBLE with ink cartridges. They use a chip of sorts (apparently a MCU or similar) in the actual cartridge to prevent anyone from refilling them.
http://forums.hackaday.com/viewtopic.php?f=3&t=735 <-- problem

So, then I need to think of something else entirely! I am thinking of sticking the copper clad into my printer, and have the printer print the thinnest it can onto the PCB, so I can still see the trace. Then I can run over each trace with an etch resist pen. Now that I think about it though, it does not seem too reliable because the thickness of the pen tip or marker would come into play and easily limit the thickness of traces to something larger than 8 mil.

I guess I will keep looking and trying to find something out. Maybe will rethink photo resist, since I have heard lots of good things about it, and it is pretty much the only other option for me other than getting a laser printer or purchasing online. I also need to find what chemicals I can use as enchant.

[hak8or]

A small update, with something that I consider really awesome.

Batch PCB costs:
$10.00 (set up fee) + $2.50 per inch + $3.00 (shipping, they do not say so I guessed according to "shipping in the US can be quite cheap (USPS ... ) "
DorkbotPBX costs a flat $5.00 per inch per for three board including shipping.

Right off the bat dorkbot seems cheaper because you get three boards for the cost.

I made a little graph thing comparing the cost of batchpcb vs dorkbot. This does not include the other two copies of your board in the board in^2 count, because in this situation I only care about having one board, I don't need the other three, in which case I would have given the other two boards away for free on dangers prototypes. :P Basically, use DorkbotPBX if you your design is less than 5 Inch^2.

So I looked at photo resist, and to my surprise the cost per square inch is super low, compared to the other services.
http://www.circuitspecialists.com/print ... tized-pcbs
I did some simple math to find the cost per inch^2 for you guys.
3 X 5 Single side ($6.46) -- $0.43 per square inch of copper
4 X 6 Single side ($7.13) -- $0.30 per square inch of copper
6 X 6 Single side ($8.09) -- $0.43 per square inch of copper
6 X 6 Double side ($11.40) -- $0.16 per square inch of copper
6 X 9 Single side ($11.91) -- $0.22 per square inch of copper
6 X 9 Double side ($15.26) -- $0.14 per square inch of copper
8 X 12 Single side ($19.09) -- $0.20 per square inch of copper
8 X 12 Double side ($21.49) -- $0.11 per square inch of copper
The cheapest overall ratio is 8 x 12 double sided.
The cheapest single layer ratio is 8 x 12 single layer

Then I checked the cost of shipping, BAM, $11.45. There is no way I am going to pay nearly twelve dollars for shipping something like that, so I checked other sites like Ebay, but Ebay has these types of boards only shipping from China, and last time I ordered something from China on Ebay, and it took nearly two weeks to get here, so that is out.

Turns out Amazon has a seller that does not overcharge to no end, and much more reasonable shipping costs.
http://www.amazon.com/gp/search/ref=sr_ ... _authority
I am going to get 6 X 9 Double sided for $17.12 with shipping being only five dollars. No reviews though, so I will most surely tell you all how they are when I get them!

I am most likely going to stick with the photo resist that I have shown above, since it is far cheaper than online PCB services, and pretty much the only way I can make PCB's at home without a laser printer or using a pen. I was thinking of the spray on photo resist, but after hearing that it needs to be pretty much Dust free and all done in a very dim room, I think that I can't use it. Mostly because I don't have dim room anywhere that is also very not dusty. :P

I hope this will be of use to anyone of you who read this!

Now, I need to worry about the chemicals. :P

[ian]

Nice price comparison graph, that is interesting. It would be super cool to have one with all the majors on there (PCB123, Itead/Seeed, Golden Pheonix, etc).

Have you checked Seeed or Itead's PCB service? You can get 10 boards starting at $13 including worldwide shipping ($1.30 per PCB). Turn around is quick, and the internal post is flying fast right now (most packages are China to me in 4 days).

in which case I would have given the other two boards away for free on dangers prototypes. :P

It's always fun to add guest PCBs to the PCB drawer :) Give me a shout if you have extras.

[hak8or]

Nice price comparison graph, that is interesting. It would be super cool to have one with all the majors on there (PCB123, Itead/Seeed, Golden Pheonix, etc).

Have you checked Seeed or Itead's PCB service? You can get 10 boards starting at $13 including worldwide shipping ($1.30 per PCB). Turn around is quick, and the internal post is flying fast right now (most packages are China to me in 4 days).

in which case I would have given the other two boards away for free on dangers prototypes. :P

It's always fun to add guest PCBs to the PCB drawer :) Give me a shout if you have extras.

I may be interested in making a graphic comparing other PCB vendors, but there are so much different variables in the cost, for example trace width, lead times, do I add in shipping costs, and drill sizes. That would require a lot of my to make a proper graph with all of those things. Also, most PCB fabs don't include the equations they use for determining cost, and some even don't tell you the shipping cost till after it is fabbed. 4PCB did that to me, 25 dollar shipping for a 66 (10 in X 6.6 in I think) inch PCB is just ridiculous, especially since it is a flat very thin object. Though, I will most definitely want to make such a graph even though it may be problematic to find what values to use for what for a fair comparison. I did just find some good graph thing online that also actually looks nice and is usable. Too bad you cannot set the thickness of lines.
http://desmos.com/calculator/#

I did do a quick look see on that PCB service, I have always heard of them but never actually tried them myself.
http://www.seeedstudio.com/depot/fusion ... p-835.html <-- is this what you were referring to by seeed's PCB service?
Earlier I thought that it was ten dollars per board, which led me to write this.
It appears that the minimum quantity is ten boards, and each board is 9.90 which results in it costing $100 for a single design which would be 5cm by 5cm. The cost for a single board would be $25.81 per inch of board, which is far far above what batchpcb
Then I realized that it was for all ten boards combined! That is incredibly cheap! So, for ten dollars you get (5 cm X 5 cm) 3.88 square inches of design space, 10 dollars, leads to $2.58 per square inch.

======================================================
Here is the cost rundown for seeed's Fusion PCB service:

*Math has been fixed*

Keep in mind, this is using all the default options for seed, I am counting only one PCB instead of ten, and it does not include shipping. I had to make this as a PNG because this forum does not seem to follow spacing. :( I also just realized that dangers prototypes cut off my pictures since they were too big, so i resized them.

[ian]

Wow, thanks, that's an interesting look at Fusion. I didn't necessarily mean you should do the chart, just that it would be cool to see one :)

For the 10@ 10x10 I ususally get it is around .17 per in2 including all the PCBs, which is not so much greater than the other services you list. It's great to see PCBs coming down in price, a few years ago it seemed like it was Olimex with no plating, or nothing.

The think I like about Fusion is that the shipping is really cheap, to anywhere in the world.

[hak8or]

Yeah, I normally do this type of cost comparison whenever I get a board done either way, so I might as well make it in a presentable manner so I can give it to the rest of the community. :P

If you want more than one copy of your board, then I guess seed has the absolute cheapest start up cost. Ten dollars for ten copies of your board? That is very cheap, even though the board is pretty small. :P Unfortunately I was never that interested in making boards years ago, so I cannot compare the cost of PCB's, but I do presume that it was much more expensive for the hobbyist.

Good to know the shipping is cheap. :P I will never allow myself to get screwed over by shipping again, especially after the incident with 4PCB charging me so much for shipping. The reason that I am so dis interested in getting a board done by a fab plant is because I want to have the ability to think of an idea, design a board, etch the board, solder on the parts, test, and actually use the board all in one day. I am a very impatient person. :P Granted, I may not have the parts on hand at the moment, making PCB's myself will most certainly decrease the amount of times that a project was put "on hold" due to either forgetting what the original goal was, getting discouraged by waiting more than a week for a board/parts to get here, or not wanting to because of the knowledge that it will take a very long time to complete, most of it in waiting. For me, this will be a large step forward, and will definitely make me more productive. Plus, it appears that making your own PCB for something brings a lot more self gratification at the end when it all works. :P

*it appears that I am derailing my own thread too :P *

[hak8or]

There has not been much progress in the past few days, I was mostly checking out what parts to use, and trying to find out what CPLD or FPGA to use for taking care of the high speed data transfer (50 MSPS, 8 bits). I would want to use an FPGA because I could use the SPI flash instead of using a JTAG.

Either way, I got the pre-sensitized PCB this morning, but I cannot do much because of the latest natural disaster. Hurricane Irne right now, earlier the earthquake. If anyone here is on the East cost, I hope that the hurricane does not do any damage to you!