Using 12v System to Directly Power Computers and other DC Eq.

[JPC]

Does anyone have a recommendation or experience with a setup for powering non-marine DC-powered devices (computers, the obvious example) from the 12v system? Hopefully this is a dumb question and that will be pointed out to me.

Since so many products are DC (but call for varying voltage levels and are designed to rely on specific AC adaptors in home applications) it seems that it would be efficient to power these directly from the 12v source. How have people dealt with the range of output voltages that would seem to be required? A panel full of auto-cigarette-lighter-adapters doesn't seem too clever. What is a practical means for having a variable-voltage DC output or, alternatively, is there a simple device that can be placed between each device and the 12v source to supply proper voltage/current to that device?

Thinking of desktop computer equipment, is there a practical means to supply 5v power directly to the components?

Thanks for any input

-JPC

[marshmat]

Well, laptop computers can require anything from 12 to 19 V; other electronics all have their own requirements too. DC-DC converters could do this, but that gets pricey, especially when you add the circuitry to clean up the output. Simple resistive voltage dividers can give you <12 V power from a 12 V source, but that's not very efficient.
Computer equipment can be really sensitive to fluctuations and surges in the supply voltage. A computer's power supply is filtered against noise and fluctuation, as well as supplying very stable 12, 5, 3.3 and sometimes 2.5 V power to the components. You'd have to duplicate all of this functionality.
Seeing as most components are designed for standard voltages- 120 VAC, 240 VAC or 12 VDC- it seems to me that the usual system of sticking with these standards is probably easiest.

[Tim B]

Better than a potential divider is a variable voltage regulator (or several in parallel if you need the current handling).

Desktop computers are a bit simpler, though. You can get a module from http://www.logicsupply.com/index.php/cPath/40_65

Do remember though, Salt-water is the enemy of electronics.

Tim B.

[Syed]

Some devices have more than one internal power supply levels and they have to be kept isolated (require galvanic isolation). It will be difficult to operate these devices from a single DC source. A/C to D/C conversion is pretty efficient and simple.

[TerryKing]

This used to be a little difficult, but lately there is so much demand for vehicle-based PC's that there are a lot of available power supplies that are 12VDC (or up to +36VDC or so) IN and ATX or other PC standard power OUT.
Some of them , for small single-board X86 - Win-XP type computers are not much bigger than your thumb! Let me get a few references... (digs thru bookmarks....)

One for $50
http://www.aerial.net/shop/product_info.php?currency=USD&products_id=171
Another: 200 Watt, multiple output
http://www.mini-box.com/PW-200M-DC-DC-power-supply?sc=8&category=13

A nice motherboard about $150, which I think I'll use:
http://www.via.com.tw/en/products/mainboards/motherboards.jsp?motherboard_id=202

Most of this technology comes from the Car-PC guys putting GPS and MP3 in their Camaro etc etc..

This stuff is great for those of us who can't decide if we're a computer nerd, boatbuilder fanatic or TIG Pilot...

[Frosty]

Almost everybody uses a lap top for Cmap navigation driven from nmea 0183 GPS.

You WILL be able to get a correct fitting to drive your lap top from a cigar lighter socket.

I would add that you might want to think carefully on the battery supply ie what battery bank you use. For instance if you have a dedicated engine start ,that would be good as you would take the power source from another--house bank say. Otherwise you will get some shut downs when you hit the starter.

Incidentaly I take off power for all my instruments from the house batteries--simple for the reason that I might want to see the depth or my position with out switching on main engine starts.

[TerryKing]

Almost everybody uses a lap top for Cmap navigation driven from nmea 0183 GPS.
You WILL be able to get a correct fitting to drive your lap top from a cigar lighter socket.
I would add that you might want to think carefully on the battery supply ie what battery bank you use. For instance if you have a dedicated engine start ,that would be good as you would take the power source from another--house bank say. Otherwise you will get some shut downs when you hit the starter.
...

Jack, a couple of interesting things here:

One advantage to using a separate computer rather than a laptop is that the laptop can be very easily damaged, especially with salt spray possibilities.. Also, the cost can be much less for the same capabilities... but more work to 'install'! Also the possible interfaces and options are much greater.

The better 12V vehicle power supplies for PCs will not shut the PC down when starting a car, on the same battery. But I personally agree that on anything other than a small boat, there should be a separate starting battery that is disconnected from the onboard systems when engine starting.

[kmorin]

Several firms, like Vicor, make a solid state DC to DC converter . http://www.vicr.com/products/dc-dc/converters/dc-dc_converters/
http://www.vicr.com/products/dc-dc/converters/mxmnmc/
http://www.wallindustries.com/productcart/pc/viewCat_P.asp?idCategory=89
http://www.power-one.com/products/dcdc_overview.html

Vicor's mega-mod Jr converters can provide solid clean DC at different voltage levels from the input.

Having used them for a decade to run PLC's, PC's and RF modems in remote locations where all the power was 12 VDC; I'm sure these converters will deliver reliable power at the exact output levels specified.

They're not inexpensive but they're reliable stepping DC voltage UP -OR DOWN.

They work as a defacto filter for noise and input spikes or fluctuations too, since the clipping tolerance @ the output is so tight; you end up with excellent quality DC output in addition to the level step changes.

Using these converters you can provide super 'clean' power of the exact voltage level needed for any DC powered device. Often, when you take apart PC or comm equipment OEM power supplies you'll find that the primary power output is converted down (an up) by just these exact components; even the brands linked here.

Cheers,
kmorin

[charmc]

Vehicle DC chargers/power supplies are readily available. The intermediate black box functions as a power filter also, protecting against spikes and such.
Here's one that fits different devices by changing the plug tip. Only need one charger, charge up to 3 different devices at once.

http://www.igo.com/product.asp?sku=2366908

I agree with the advice to install an isolator and have separate batteries for engine starting and for everything else. I did that with every boat I owned, anchored out for days at a time, ran various electrical goodies according to whim or need, but always had a fully charged bank to start engines.

[Trevlyns]

A cheap and simple option to me seems to be a power inverter – just plug that into e-bay (pardon the pun :D ). It converts from 12V to mains power so my computer can be recharged, or run directly from, a mains source.

[TerryKing]

I've been looking at this for a while. The power budget for running a moderately capable X86 computer that is optimized for low power seems to be about 20 watts (25 if you're playing an MP3 or watching a DVD). See http://www.epiacenter.com/powersim/powersim_v2/epiasimulator_v2.htm
for some possibilities.. I'm thinking I'll probably run a VIA MII 6000E.

Some expensive (About $4200) commercial Boat Computers like SeaPC http://www.seapc.se/items/luna.html use a board like this. For power, they say:"The average power consumption is 30 W or 2.5 amps on a 12 v system."

I think it's hard to get a Laptop that is running thru an inverter supplying 12V to 120/220 down to that power. Can someone who's doing this measure the current at 12V on such a configuration, for a 600 Mhz or more machine running WIN-XP or Linux, with the screen active??

One problem is that there are two active power-converters in the system (not counting what the PC is doing internally) that each have a less-than perfect efficiency..

Those making a passage under sail care about this more than weekend sailors...

[Tim B]

I measured current some time ago at 12 volts:

No-load 0.9A
Laptop 6A
Acorn A7000 2.6A (search the web if you're wondering what this is)

as I remember a desktop machine was about 12A

Except for the laptop, these do not include the current drawn by the monitor.

The big problem is not actually supplying power. It's cooling the CPU in a manner that prevents corrosion to the motherboard.

Tim B.

[TerryKing]

..(snip)...The big problem is not actually supplying power. It's cooling the CPU in a manner that prevents corrosion to the motherboard.
Tim B.
That problem is addressed pretty nicely by the lower-power VIA chipsets and the Eden processor, which allows an 800 MHz machine with fast memory and built-in graphics that support DVD playback, with NO FAN. See the Mini-ITX motherboards at:
http://www.via.com.tw/en/products/mainboards/motherboards.jsp?motherboard_id=202
A quote is: "The VIA EPIA MII is available with the fanless VIA Eden™ ESP processor for ultra low power, quiet or silent system designs". This 17x17Cm motherboard is used in a few different $2000 - $4000 "Boat Computers". But it costs about $160 for the system board with processor (soldered..NOT socketed).

So that's where I'm headed right now....

[Portager]

For really low power applications I like to use low power PC/104+ processor boards such as AMPs Micro886ULP http://www.ampltd.com/prod/u886.html which is a low power Pentium III class PC/104+ processor. To run off DC power, I add a PC/104 power supply such as http://www.tri-m.com/products/engineering/#power . The PC/104 power supplies have a wide input voltage, for example the HE104 has an input voltage of 6 - 40VDC. Most of these power supplies provide power to the PC/104 stack through the ISA and PCI bus connectors so there is no wiring required between the power supply and the cards. If you plan to use the PC for a navigation system then you will need more storage space than is economically feasible with flash, so you can add a 2.5" hard drive with a PC/104 Hard Drive Mounting Board http://www.diamondsystems.com/products/hddmount . The PC/104 cards stack together like a sandwich and then you can seal the stack in an enclosure of the correct length such as the CT104 http://www.tri-m.com/products/engineering/ct104.html . They have standard end caps that handle most requirements http://engineering.tri-m.com/products/enclosures/CT-stdendcap.htm . For boat applications with a hard drive I don't trust the rubber grommet shock isolators so I replace then with wire rope isolators such as http://www.isotechoem.com/pdf/WireRope.pdf . I use the "VEHICULAR / Rough Terrain (Off-Highway) / 20Hz Vertical" table on page 21 or 25 to guide the selection and give a 20 Hz natural frequency. To deal with salt air corrosion I like to mount the PC/104 stack in a sealed enclosure. With the ultra-low power processor you are supposed to be able to run it without a fan, but I usually put a stirring fan inside the enclosure to prevent hot spots. I like the Parvus Thermocool PC/104 because it is thermostatically controlled http://www.parvus.com/support/SupportPage.aspx?ProductID=55 which saves a little power when the fan isn't required, but also helps to keep heat in in low temperature operation.

If power and corrosion are less critical and you want a turn-key solution, then I like the Stealth Computers fan-less Little PC http://www.stealthcomputer.com/littlepc_fanless_p4.htm . Use the shock isolators mentioned above and you're ready to go. I can provide a picture of a Little PC installed on Shock Isolators for a 45 knot boat application (next time I take my camera to the boat).

BTW: My favorite GPS/compass is the Crescent Vector OEM started kit because in addition to accurate position it provides heading to true North to within 0.2 degrees at a rate up to 20 Hz. The accuracy and stability is excellect for driving an autopilot and you don't need to worry about declination, but that probably another thread.

[marshmat]

A few more options here for the technically inclined, if you want to run stuff like computers etc. directly on DC without an inverter.
For those with a bit of electrical knowledge and who like building their own stuff, I highly recommend Vicor's DC/DC converters as the starting point for your system. They're simple, reliable solid-state devices and are very efficient; they have a huge selection of input and output voltages available, http://www.vicr.com/products/dc-dc/converters/ . If you run a 24 V or 48 V battery bank, it's not hard to wire up their converters to give you anywhere from 2 to 48 VDC, and the output is clean enough to run even the most sensitive electronics. We've had very good luck with these in solar cars, running with wildly fluctuating input voltages and at insane temperatures; the converters don't flinch one bit.
The same company also makes a range of ready-to-run power supplies for all manner of DC/DC applications, http://www.vicr.com/products/configurable/ . It shouldn't be too hard to find something there that would suit whatever you need to run.

[Hank Rosendal]

I think "Marchmat" hinted earlier on, why not stick to the mains (110/220/240) voltage with an (DC/AC) inverter? It means a lot less boxes and converters of many kinds, it remains flexible for future equipment. By all means, use the 12 Volt battery power for the equipment which uses that Voltage, otherwise use the DC/AC inverter. I have used normal (non-marinised) desktop computers on my yacht for 10 years, none have 'rusted out'. I only upgraded them to keep up with the speed. Right now I have a Shuttle: fast, small and virtullay silent.
The only drawback is that the bigger (LCD) screens, we love for the charts, are also the ones which use most of the power.

[Tim B]

Because converting from 12 volts to 240 wastes power if there's no need to do it. and when on a boat, power is the second biggest electronic problem you'd rather not have.

Tim B.

[SeaSpark]

I know it is common practice nowadays but i still think installing any 240 equipment on a yacht is ridiculous if only for the watery environment.

[TerryKing]

I know it is common practice nowadays but i still think installing any 240 equipment on a yacht is ridiculous if only for the watery environment.

Boats are unusual in that there is such a range of sizes. Smaller boats can run everything on 12V, and I'd personally want everything "important" for safety to be 12V. But at the high end, you need higher voltage to run the little extras like the A/C,the freezer and the system that runs the buttons you push to call the steward. And 220 volts and 50Hz is approaching a worldwide common 'standard'.

[alan white]

We won't ever give up our 120 volts or our extra ten cycles, Terry. We need them in case of terrorists attacking our appliances. They don't know how to hook up their dastardly timing devices to them.
Our president, by the way, has as much as said that one day the whole world will be set up for 120v at 60 hz. Even if we have to go in and do it ourselves.

A.

[TerryKing]

(snip)...Our president, by the way, has as much as said that one day the whole world will be set up for 120v at 60 hz.

His pronouncements on subjects in which he has little apparent expertise are having less and less effect every day. Even in Washington.

However,I've been back in the USA for less than 24 hours, and my brain may not yet be phase locked to the predominate signals...

[alan white]

No hurry. Enjoy that lovely weather. A bit cold tonight--- perfect sleeping weather. That is, if you're back in Vermont?

A.

[Frosty]

I know it is common practice nowadays but i still think installing any 240 equipment on a yacht is ridiculous if only for the watery environment.

Proper boats dont have salt water inside of them. 240 volts is a very sensible way to go.

The only 12 volt stuff I have on board is the nasty marine crap that I have to buy because its not available in 240 --toilets.

Power or sailing have different opinions on this. I understand different expectations of power consumption.

With engines running ( and I have to- to move) I have 2.5 KW invertor wired to the ring main.


2 fridges 80 watts and an entire kitchen with rice cooker and micro wave is usable-- (with deviation in mind).

Fans and lap top load is minimal and is almost un-measurable.

Most boats spend 80 % or more in a Marina. Why not wire it up for such use.

[SeaSpark]

Proper yachts with engines running all the time do not exist in my vocabulary :)

[Portager]

This discussion is bordering on becoming ridiculous.

It is more efficient to power DC loads off DC power even if you need a DC to DC converter. It is absurd to convert DC power to AC with an inverter to power an AC power supply which produces DC power to run a computer. If you want to count boxes then DC wins two to one, unless you don't count the inverter and the power supply inside the PC.

[StianM]

We won't ever give up our 120 volts or our extra ten cycles, Terry. We need them in case of terrorists attacking our appliances. They don't know how to hook up their dastardly timing devices to them.
Our president, by the way, has as much as said that one day the whole world will be set up for 120v at 60 hz. Even if we have to go in and do it ourselves.

A.

That is exstremly funny:D It would actualy be perfect if US switched to 230V while Europe switched to 60Hz.

Higer voltage make the machines smaler while higher frequensy enable you to use less iron in transformers.

This discussion is bordering on becoming ridiculous.

It is more efficient to power DC loads off DC power even if you need a DC to DC converter. It is absurd to convert DC power to AC with an inverter to power an AC power supply which produces DC power to run a computer. If you want to count boxes then DC wins two to one, unless you don't count the inverter and the power supply inside the PC.

I think a DC to AC inverter make more sence since you might want to use the AC power to other things than just laptops running 12VDC. Maybe you have a cellphone charger running 9VDC. Or maybe the wife just have to bring hear hair dryer;)

[Tim B]

There are certain cases (primarily hairdryers) where 240V AC is handy (I have an inverter so I don't double the kit I have) but remember that this thread is primarily about computers, and lately about on-board (ie. built-in or embedded) computers 240VAC is just wasting energy at that point.

As for standard power, 240 volts, frequency wouldn't really matter between 50 and 60 Hz would it?

Tim B.

[StianM]

There are certain cases (primarily hairdryers) where 240V AC is handy (I have an inverter so I don't double the kit I have) but remember that this thread is primarily about computers, and lately about on-board (ie. built-in or embedded) computers 240VAC is just wasting energy at that point. Converting 12VDC to 240VAC and back wont cost that mutch energy, probertly less than a candle produce. Even if you at the moment only think about computers there will allways be a time when 240VAC turns out to come in handy. For 12VDC for computer use I would be suprised if there is not posible to buy car chargers for nootbooks.:confused:

As for standard power, 240 volts, frequency wouldn't really matter between 50 and 60 Hz would it?

Tim B.

50 and 60 is really only interesting in transformers since a increase in Hz will lower the nead for iron and therfor making the transformer lighter. Not really off anny practical interest.

[Portager]

I think a DC to AC inverter make more sence since you might want to use the AC power to other things than just laptops running 12VDC. Maybe you have a cellphone charger running 9VDC. Or maybe the wife just have to bring hear hair dryer;)

As I said, "It is more efficient to power DC loads off DC power even if you need a DC to DC converter." The hair dryer is an AC load and therefore falls outside this statement. Most cell phones offer a car adapter which runs off 12/24 VDC power and this is basically a DC/DC converter that converts 12/24 VDC to the voltage that the cell phone requires. Typical power conversion efficiency of these devices is in the 90% to 93% range. Inverters convert DC power to AC power and they can achieve 90% to 96% efficiency, however when lightly loaded their efficiency drops to 80% to 85%. For an AC to DC power supply, assuming it is specially designed for the load, can have an efficiency of up to 95% but typically it will be 85% to 90% (especially for low cost consumer grade power supplies). Taking the produce of the lightly loaded inverter efficiency and the consumer grade power supply efficiency yields an overall efficiency of 68% to 80% while a dedicated inverter and high quality power supply will range between 85% and 91%. Note the general purpose inverter and consumer grade power supply is far less efficient than the DC/DC converter. Only a dedicated inverter and a high quality power supply can come close to the efficiency of a DC/DC converter. This equates to longer running time on the battery bank and less waste heat in the cabin and it proves my point.

[StianM]

I don't understand why you bring up this efficensy problem:confused:

The DC converter for my computer has a output of 4,74A(at both 100 and 240V). So even a efficensy off 50% would mean nothing. The power lost is so minimal that it's not interesting.

Cell phones nead 9V, Computers nead 12V so I just don't understand why annyone would not want a AC inverter instead and get more freedom in what equitment they can use.

I know what I would do, but everone have to find out what make sence to them.

[Portager]

StianM;

JPC initiated this thread by saying, "Since so many products are DC (but call for varying voltage levels and are designed to rely on specific AC adaptors in home applications) it seems that it would be efficient to power these directly from the 12v source."

I was responding to the original question of improving the overall efficiency, which is important on a small boat with a limited battery bank or on a small boat in the tropics without air conditioning.

[StianM]

StianM;
I was responding to the original question of improving the overall efficiency, which is important on a small boat with a limited battery bank or on a small boat in the tropics without air conditioning.

I gues it's true what they say, everything is biger in america. The powersupply to my asus 17inch nootebook is only 4.74A, my girlfriends Tatung nootbook computers powersuply is only 1.2A. The stuff you have ower in california must be huge since it's a power concern with you.

[TerryKing]

(snip)..."It is more efficient to power DC loads off DC power even if you need a DC to DC converter."
I agree, and for those making a passage under sail or anchoring for a few days in a remote spot, efficiency is important.

I'm looking to find a series of low-cost DC-DC converters that are 12V (nominal) in and have a variety of outputs available (settable). I'd like to mount them at point-of-use, have them somewhat interchangeable (within a similar power rating) and have standard 12V connectors for many low-current 12V based devices, utility lights, etc etc.

Portager, have you decided on DC connectors yet? My Son was discusing this with Jack Ganssle (Of Embedded Computer fame) who, is also a sailor. Jack uses a widely-available 4-pin connector that has a bayonet secure attachment. I'll find out which one it was and it's availablity. I have been using the old 4-pin polarized "Jones Plugs" for 20 years, but Radio Shack doesn't carry them any more!

Maybe we can work up some stuff for the Electrical Systems Wiki later on...

[hmattos]

I agree with Trelyns at post #10.
Why re-invent the wheel when you can go down to most hardware or automotive / tool stores and buy a 150 watt power invertor which will give you a good safe sine wave at 230 or 110 volts.
The cost, all ready to use, is less that 20 GBP which probably means about 30 dollars.
Great for use in the car to keep the children amused with a DVD on the laptop for the journey.

[Tim B]

Maplin still have "Locking Audio Connectors" Which are actually capable of handling a fair bit of power (I'm using them on my boat at the moment). Farnell also have a wide range of suitable connectors.

The last inverter I bought cost me £75. That's a lot more than 75p for a voltage regulator to run a mobile phone off.

Tim B.

[TerryKing]

Maplin still have "Locking Audio Connectors" Which are actually capable of handling a fair bit of power (I'm using them on my boat at the moment)
Tim, can you point to a picture / page with these connectors?? I'm trying to survey the possibilities, not just US stuff...

[Tim B]

These are they:

http://www.maplin.co.uk/search.aspx?menuno=12306&MenuName=Multiway%20Connectors&FromMenu=y&worldid=-2&doy=20m5

It's not a perfect solution, but it does mean that you can have a multi-pole connecter in a standard plate. XLR connectors also spring to mind.

Tim B.

[TerryKing]

It's not a perfect solution, but it does mean that you can have a multi-pole connecter in a standard plate.

Tim, I think the connectors Jack Ganssle and my Son were looking at were very similar, but Delrin plastic with an O-ring seal. Maybe better in Marine environment. I'll track them down and we can compare....

[TerryKing]

Assuming that adding to a list is an actual accomlishment, I have added:
# 8.3 Electrical Connectors for Shipboard Applications
As a section on the electrical Systems Wiki..

I'll put some stuff there soon, including the Maplin reference.

The worldwide property of boating is a challenge...

[JPC]

I've been away from the forum for a while, and it looks like this thread ran its course some time ago, but I thought I'd close the loop by describing where I'd ended up.

Since I had asked the original question and was looking for new (to me) information, I stayed quiet once the thread got underway, but was closely following most of the discussion and am grateful for the thoughts and contributions that were given.

Focusing on just a few of the main points, I was looking for:

1. low power;
2. reasonable robustness;
3. minimal number of additional 'parts' and connections (applying to both things like add-in video cards and things like inverters, DC converters, etc.);
4. availability, implementation, and costs in line with generic 'land' devices and not specialty marine items.

The system was to be used on a 34' sailboat; an environment that can get wet and bouncy, and a situation where power is a scarce resource. This system is principally used for navigation and communication tasks and is meant to be operating 100% of the time that the boat is not at anchor.

I'm using the Alix 1C motherboard ( http://www.pcengines.ch/alix1c.htm ) and the Hyvision MV142 14" LCD monitor. Both operate directly from a 12v DC source and consume, respectively and when not in snooze, about 5 watts and 13 watts. Within reasonable functionality, I haven't seen anything more power-stingy. Neither requires an inverter, power supply, or DC converter.

Low power means a modest machine. The Mboard has a 500MHz processor and a fixed (soldered on board) 256MB of RAM. So far, this has been fine, particularly when operating with some of the low-overhead versions of Linux (Xubuntu, Fluxbuntu, e.g.).

The Mboard further saves power and the risk/cost of additional components and their connections by having integrated sound, video, LAN, etc. No screamers, but it's all there and won't rattle loose or bleed more power. The board is intended to use a Compact Flash drive as its primary drive; it can also use and boot from USB drives or a standard CD or HDD connected by USB or the one EIDE header. Sticking with the CF or USB flash drive preserves the low power and makes for a fully functioning system with no moving parts or significant add-on pieces; this goes a long way in acheiving the robustness objective. Additional, or higher performance, storage or other devices can be plugged into the USB, EIDE, or PCI bus only when needed, so won't suck power or create a vulnerability when they're not required.

Finally, the Mboard is fanless and generates negligible heat, allowing it to operate in a water-tight enclosure without overheating, solving a lot of hassles.


It's cheap and it works. Everyone's applications are different; this one has been fine for me. Those looking for more power/capability than this, while still avoiding a standard desktop or laptop might find some interesting options at http://www.mini-box.com. If anyone's looking to do a similar thing and would like some more sources, just shoot me an email -most of my info is on a cantankerous hard drive, but if I can ressurect it I might be able to save you some time.

I've been fiddling around with a full desktop-power arrangement as well, using a sealed case and water cooling. That's more of a curiousity than a real effort, but I'll relay any info (or tales of bursting pipes) that seems useful.

Best regards,
JPC

[masalai]

Some here (connectors) - all in Australian $ including 10% gst?

http://www.dse.com.au/cgi-bin/dse.storefront/477980170018a79c2742c0a87f9c0715/Export/catalogs/CTG0005745
or
http://www.dse.com.au/cgi-bin/dse.storefront/477980170018a79c2742c0a87f9c0715/Export/catalogs/CTG0001202

and dc - dc converters here (with thumbnails)

http://dseau.resultspage.com/search.php?sessionid=477980170018a79c2742c0a87f9c0715&w=dc+-+dc+converters&site=&submit.x=9&submit.y=8&submit=Go

Regards.