440 Watt Power Supply

**zootjeff** · 10-04-2005, 12:05 AM

A few days ago I put some hooks in the firmware to take two DSATX power supplies and run them in Master/Slave cascade mode.

You set a mode bit to put the first one into master mode, then you put a jumper on the slave and it runs in slave mode. You connect two wires between them on the headder blocks and they are now operating in harmony. A short circuit on the output of the slave or the master shuts them both down. An over temperature on either one shuts them both down. PS_ON on the master turns them both on (within 40ms of each other....) It is useful if you want to power your 3 hard drives, and 2 dvd roms and still have some left over for the LCD screens. You have to sacrifice the Aux output though (AMP turnon). Your motherboard has to get all it's power from the Master though so it's not limitless.

I tested it with two power supplies the other night. You could also cascade 3 or 4 of them together. Maybe I should have started this post as a 960 Watt Power Supply!

I thought about designing a 400 watt power supply but the limits of 12 volt wiring would mean that 40 amps would be coming into your input terminals. If you look at how inverters do it, they have 4 gauge wire soldered right to a board and put in an extruded case with big lugs. Maybe when I'm rich and famous, I'll try something like that, but for now the cascading seems like a pretty nice alternative....

**greenman100** · 10-04-2005, 01:05 AM

Your motherboard has to get all it's power from the Master though so it's not limitless.

that is an important note to make.

But yes, everything else makes sense.

**Chris31** · 10-04-2005, 03:03 AM

cool,

300 + watts is nice but I think the problems is else where.

Car pc should really be using less power hungry components so we wont need all these expensive PSUs. An efficient P4 2GHz+ can easily run off a PSU rated at less than 90W.

**greenman100** · 10-04-2005, 03:06 AM

Originally Posted by Chris31

. An efficient P4 2GHz+ can easily run off a PSU rated at less than 90W.

HD - 10w
VGA screen - 10w
USB kb/mouse - 5w
Wifi - 10w
Ram - 5w
MB - 10w
fans - 5w
DVD - 10w

so that leaves 25w for your CPU? I don't think that'll work....and that's not counting additional USB devices, LCDs, etc

**Chris31** · 10-04-2005, 04:11 AM

Sorry I meant efficient = laptop components.

Much more suited as a car PC than a high power desktop machine.

**rushnrockt** · 10-04-2005, 04:44 AM

Originally Posted by Chris31

cool,

300 + watts is nice but I think the problems is else where.

Car pc should really be using less power hungry components so we wont need all these expensive PSUs. An efficient P4 2GHz+ can easily run off a PSU rated at less than 90W.

A 150W limit is much more reasonable. My P4 based laptop has a 160W power brick, and that's considering that it is mostly desktop components and has a 15.4" screen.
The question here is more of all the additional components that people would like to be able to add. A 440W PSU might be an overkill for most, but leaves quite a bit room to play with the cheapest components out there, and in this expensive hobby, that's a big plus.

**00christian00** · 10-04-2005, 06:04 AM

My carpc was fine with 150w until i were using a regular sound card,but when i replaced it with a rack audio self-powered by the motherboard i started getting problem because i hadn't enough power.I removed some ram and fan,and replaced hd with a notebook one but still,even if now it is rare,i have some problem.So definitely there is the need for a larger psu.Consider also that "power hungry devices" are also a lot cheaper than laptop parts and that already is more than enough to request a more powerful psu.

**port20** · 10-04-2005, 06:52 AM

Jeff mark my words sooner or later you will be designing a 12v 400 watt ATX pwr supply if you were making one now I would buy one most of us would rather run a P4 3.4G but as of now the best we can run is P4 2.4's because nobody makes a supply that can power a 3.4 G system

cascade pwr supply systems never seem to work well with every system I have seen a few systems where they worked fine but I have seen many more where they were very hard to keep working a single supply is the way to go so get started were waiting

**Chris31** · 10-04-2005, 01:07 PM

With the current trend we can see that high power output PSU are needed. It started with something like 40W, then we have 60W, 90W, 150W, 200W, 250W, 300W, 350W now we are reaching 440W...

I wonder where it will stop, would it be still practial to put a 1000W PSU in a car? Im sure someone out there will.

**Chris31** · 10-04-2005, 01:21 PM

Originally Posted by rushnrockt

A 440W PSU might be an overkill for most, but leaves quite a bit room to play with the cheapest components out there, and in this expensive hobby, that's a big plus.

440W is good, Ill take it if they sell for the same price as the 150W.

The opus 150W for carPC is already expensive, how much would a 440W go for? He did talked about putting them in parallel = 2 x price and 2 x size.

How much are you guys willing to pay for a PSU?

If I want to run my carPC cheap, high power, uses desktop parts and not care about its efficiency...Ill probably go for a good inverter, since efficiency is not an issue.