Thread: Group buy for the cheap MagicPower 120W MPD-810H DC-DC PSU

plug it in, power it, attach it to your PSU and go

It's turnkey, you don't need to do anything else to it. You might want to add in a shutdown controller or something to automatically turn it on and off, but other than that it's ready to go.

Originally posted by johnny010
will this thing you are possilby doing the group buy on eliminate all noise?

Almost certainly yes.

Originally posted by johnny010
i have an amd 1.4ghz, nesa 7in screen, xbox, cdrw, ide to usb 2.0 converter and usb 2.0 hub.....will all this work?

Well the 1.4GHz can draw 65W maximum (13A on the 5V rail, already 3A over the maximum) which means if you want to use it you'll have to underclock it (do you really need 1.4GHz in your car?) Running at 933 (bus at 66 instead of 100) it'll only draw a maximum of 8.7A, which should be fine. The screen can run easily off of the +12V regulated from the PSU, do you plan on burning CDs while in your car? (Do you really need a CDRW in your car?) IDE to USB2.0 converter (?? using what?)... However the x-box is a no-go, it'll draw a lot of power (max 36W for the processor alone, probably another 18W for the graphics card, so you're looking at ~5-6A at 12V). You'll need to build a special converter for that, or I don't know if you can hack it to run directly off the car's power. However I don't think it matters which DC-DC PSU you get, you're gonna have a hard time running an x-box off of it.

Originally posted by johnny010
Well I may be interested....you guys say that you have induced noise with your inverters...how much noise? Mine makes tons of noise...turn the stereo up and it gets louder...turn it all the way down and no noise at all????

Everything makes sense up to the point where you say that nothing is turned on when this phenomenon is happening. 120VAC at pseudo 60Hz will cause a brutal hum in your audio system if any wires carrying current runs next to a wire leading into your radio, however there should be no noise if the cable is not carrying current. You say that if you plug the extension cable into the inverter without anything plugged into it, there is no noise, but as soon as you plug something into the extension cable there is noise? This sounds very very strange because, again, if there is no current draw then nothing should happen. If, however, this only happens when there is current draw then it makes sense.

What type of inverter do you have? Try to run power cables (ALL power cables, including power TO the inverter) away from any speaker wires or radio wires). You can try to buy a different inverter, see if that solves your problem, or try to buy a radio noise filter. Additionally you can try to put noise inhibitors on all power wires running into your inverter and radio, and how do you have your inverter plugged in? Make sure that you are using thick wires, and that the ground wire for the inverter is close to the inverter itself and is in the trunk, securely attached to the vechicle chassis. Do you have amplifiers in the trunk as well?

Originally posted by johnny010
1) i have the ide to usb 2.0 converter so i can burn cd's..the computer is in the trunk and the cdrw is in the glove box...thus the need for the converter

Why do you need to burn CDs in your car??

Originally posted by johnny010
2) the inverter is grounded in the trunk, close to the unit. i tried grounding both the stereo and the inverter in the same place but no luck. i tried different inverters but the same LOUD NOISE was still produced.

What gauge wires are you using? Can you elaborate a little more on what "LOUD NOISE" means? Are we talking about a 60Hz hum, or ... ?

Originally posted by johnny010
3) the only thing I can think of when I plug the extension cord to the power supply is that the power supply is turned on....but this doesn't makes sense b/c when I bypass the strip, and plug in the xbox directly, without turning it on, i still get the same loud noise.

So essentially you get the same loud noise regardless of if the extension cable is plugged in or not?

Originally posted by johnny010
4) when the extension cord is plugged into the inverter (in the trunk)...and run along the driver's side....without plugging into the power strip, there is no noise...however, if I move the extension cord more toward the center of the car (stereo is in AUX mode)...i begin to pick up a slight buzz noise....if I move the extension cord toward the speaker wires...no noise...if i move it toward the stereo face plate, no noise (the face plate is mounted away from the brain of the cd player, which is mounted in the glove box...).....if I move the extension cord toward the stereo, noise gets louder.....move it toward the xbox (mounted behind stereo, under glove box) , slight noise but not much.

So you have nothing plugged into the inverter except for an extension cord, and if you move this extension cord (with nothing plugged into the inverter except for this cord) towards the head unit, it starts making a buzzing noise?

"I am currently using a DC-DC power supply that comes with a Mini-Itx Case that I bought. I think your main problem is the inverter. If you read thru some posts on MP3car, you will find that most of us that are serious about sound quality will use some sort of DC-DC power supply to run everything. What I would do, for the X-Box, is find out if there is a automotive adapter (or just see what the output is of the ac adapter) and use that. it is probably 7.5 or 9 volts DC that it needs and you should be able to find a regulator like that pretty easy. "

There will be no "car adapter" for the x-box since (a) it was never designed to be run in a car and (b) it takes a direct 120VAC and has an internal power supply. What you can do, however, is remove the internal power supply (keep in mind that the x-box is just a PIII/733) and put in a normal ATX DC-DC PSU. I don't think that a sproggy would do it because the x-box will be intensive on the graphics, which is run off of the 3.3V rail, most likely needing > 10A to run, plus an additional 35W on the 5V rail for the CPU, plus the USB controllers, hard drive, etc. An Opus *might* be able to power this, I don't know.

Originally posted by johnny010
thank you again for all your help Telex. Please, if you have more questions, ask away.

No problem, but this is quite a doozy.

ok great, is there anyone else that wants one?

It's looking like I'm actually not going to be getting one, seeing as how I have a working sproggy now and enough parts to add the extra power to it that I need (not to mention not a lot of money).

That's OK though, because as I pointed out we'd need someone in the US to do the bulk order, otherwise the cost goes up by like 10% because of stupid Canadian import taxes.

I've also got the shutdown controller specs and am working to add that into the sproggy design.. nice because you can re-use a few of the components already in the PSU so it'll be cheaper than an external solution.