Alexb

iTrader: (1)

Okay. This mainly applies to people who have put one in the trunk, and applies to people who still have the stock HU.

I am getting CRAZY radio interference at times and in certain spots. But only with the pc on and the second I turn it off it goes away. I got a ground loop isolator, ferrite beads, grounded in a few different spots, nothing works.

But if I have the pc on with the interference and I open the trunk, BAM the interference is gone. Altogether. So obviously it is something in the trunk, the case, the mobo, the grounding, I have no idea.

So if you have any advice or have this problem PLEASE let me know!!!

hoss -05

iTrader: (4)

Define "CRAZY"? In this case what is crazy to you. Is your radio blinking on and off like a scene out of the movie ET? Are you getting a Hiss or static when using FM AM or the tape player? Is the problem happening on all the speakers if it is a hiss? You did not give us much to go on.

I would install a Flyback diode in line with the power supply for your PC. Also If your problem truly is RF I would try some anti static bags cut up and placed around the power supply of the pc. There is a Ton of stray voltage on Most motherboards that can cause much noise. This problem can bad when a Cheep mother board or a mother board not meant for the application is used.

All the large scale Military electronics vehicular bound projects I have worked on employ Many tricks to help isolate these problems. Typically when these problems happens it a poorly designed system. Chassis design is really the key to a sound electronic component.

The diode I had listed can be found cheep at a internet retailer such as digikey.com just don't go looking at your nearest radio shack those guys dont know SH*T anymore. I would order two and put another one in line with your ground as well.

This really should not happen and you are currently only putting band aids on the wound. I would look into a different way of doing this project all together.

hoss -05

iTrader: (4)

http://en.wikipedia.org/wiki/Flyback_diode

Alexb

iTrader: (1)

Well what makes me almost certain it is RF interference is the fact that when I open the trunk it goes away. Because the interference is somewhat 'boxed up' in my trunk.

My power supply has given other people trouble, but I'm not so sure getting a new one will fix it, because it hasn't always for others

I am going to plug the pc into a standard power supply in the trunk and see what it does, if it goes away I know it is the power supply, or the wiring.

Then I'll tap the 12V rails of the AC power supply and connect them to the exisiting car DC psu. Discovering if it is the wires or the psu.

So hopefully I can figure it out.
But I've also heard people shielding the wires going to the radio antennae work... how can I do that for cheap?

psonoda

If you want to confirm rf noise, you need to test the system by isolating the power system of the computer from your factory electrical system. I would recommend using a external 12 volt battery or power from another car just for the in car PC. If you still get the same noise, then there is a non power noise problem. Also, a rf noise can be increased by moving the noise causing device next to the noise receiving device. Moving the PC and or power supply around the is a good way to see if that is a present.

Alexb

iTrader: (1)

Good suggestions!!!

Keep them coming!

hoss -05

iTrader: (4)

I would try electrostatic bags commonly used in electronics. If you think that sounds crazy put a GSM cell phone in one and put it near your computer speakers! That annoying buzz when you get an incoming phone call or txt msg will be Gone!

99% of anytime any of the systems I have worked on had problems with unrestrained RF "linked to the actual box itself" It has been the power supplies and as crazy as this sounds shitty cooling fans.

Alexb

iTrader: (1)

I like that idea. however, I just modded a regular old AC ATX power supply so it did what the car battery would do. So my m2-atx automotive psu was hooked into that. By doing that I eliminated about 90% of the interference. Then I ran the pc straight from the AC ATX supply and 100% of the interference is gone. Which makes me think it is my wiring. particularly my grounding.

So my next step is to find a good ground outside of the car and see if I still get the same interference.

hoss -05

iTrader: (4)

See there you go! there is a Ton of noise in a cars electrical system. You need an isolation kit for power as well. Our alternators are known to though out some crazy stuff. You can never have enough Ground Trust me!

I have found faults with vehicles when installing equipment. I have found my fair share of weak alternators and bad grounding systems at random when the operator of the vehicle did not even know a problem was there. It cannot hurt to run a extra ground wire or two from the battery to insure your chassis is getting a good ground. Heck the best way to insure a good ground is run another wire from to terminal straight to your PC! Just make sure the run is 3-4' away from the positive run.

That being said how are you running your +?

In super expensive super RF sensitive Million dollar plus military systems RF is tightly controlled not by patch fixes but good design. LOL at least that is the idea but also they have extra protection with electrostatic coatings fine wire mesh and Large Grounding plates over any equipment that may cause RF. they will even go as far as mounting the cooling system far away and ducting the air in. I only wish I could show you some of my past handy work

After you get your wiring system put into place to your satisfaction and you are sure you are getting Great power If things are still screwy I would get a different power supply.

9krpmrx8

iTrader: (46)

Good info.

hoss -05

iTrader: (4)

Ha this is my forte... kinda. People get phd's on this kinda stuff. I only know the mill spec side and how to fix and keep problems from happening. Ha at this point in my in my work life people only call me when they have a problem or need someone to support a engineer with no field grade military experience. I have been doing this now for eight years I hope I am getting the hang of it by now.

Alexb

iTrader: (1)

What is an isolation kit for power?

and my + line is run from the battery, with an inline fuse (15a I believe) down into the cabin by the driver's feet, under the door sills, under the rear seats and into the trunk.

And what do you mean by "Just make sure the run is 3-4' away from the positive run."

hoss -05

iTrader: (4)

positive and negative lines should not run directly next to each other for long distances as this can create extra noise in line. OK so what gauge and where are you running it? What is your nominal amp draw?

I'm sorry I think a bit differently them many people by "isolation kit" I really mean a plan to isolate points of failure plan that you put together and implement.

It is really easy to do a few extra steps that may help out in the long run. The first being make sure you have a good ground, Its a Easy thing to check and any cheap multi meter can help. Do a quick google on tips for using the meter for such tasks and others. I think your Real problem is your power supply and there are a ton out there that do this sort of thing. Even so there are ways to control this sort of problem even with a lesser power supply. I have suggested a few some even really cheep!

Once again if it were my system and I had expensive components I was worrying about frying the last thing I would skimp on is the power supply. You want to look for a power supply that has a good range of accepted voltage input, a good RMS wattage, proper output voltage throughout the entire range of input voltage and truthfully the general build quality of the unit. sometimes your electrical system in your car will see 10 volts with the car shut off, during driving you can see as high as 15 volts or better. In electronics that is a huge range and less expensive power supplies that can take that kinda range take hits in other areas such as EMI and RF noise but generally for there application its accepted. The idea of a PC powered by your cars electrical systems is truly a new one that many suppliers have yet to catch onto.

We have to be innovative in these respects this day and age. The people that have these solutions in place already are mainly doing there business with large corporations and the government. To develop a good solution to something like this and market it to the general public us at this point is going to end up costing us the cash money. There are good solutions out there but you get what you pay for. A little time spent working out the problem on your own can save you many $$ at the hear and now.

Alexb

iTrader: (1)

Well. My + line is alone. It does run by factory wires, and a lot of them. but the computer ground and any major grounds are not near it.

I think it is 12 gauge. Might be 10. That is true for both power and ground.

As far as googling for multimeter tips or whatever, I'm not sure that I really know what to be looking for?

Also, I don't know if you do, but do you have an automotive DC-DC psu to suggest?

hoss -05

iTrader: (4)

Well really you have two options ether make do with the psu you have or get a new one. You Can make do with the current unit. Ill show you two products that would fix at least some of your noise.

#1: I have used this product in the past with Great success but it dont think It is good for your application. Its the best thing out for laptops that is for sure!

http://www.lindelectronics.com/cgi-b...al_DC_Adapters

#2 This thing would work Great I like this product.

http://www.proxicast.com/shopping/in...oduct_id=29874

Both could be costly patches for a inherently bad psu and may not support enough amperage that your computer demands.

The power supply I would pick up would be:
http://www.powerstream.com/DC-PC-12V.htm

I think you should try a few things before you go out and spend the cash. Trying running a small ground wire from the battery terminal to where you have the system grounded. It dose not have to be a huge cable that you are spending a bunch of money on. A 10 gauge would even do the trick. Any good audiophile should have some 10 gauge speaker wire laying around somewhere. If you dont have any pick some up I'm sure you will use it at another time. Do not use this wire as a sole source of ground but think of it more as a helper.

Whenever I use a power supply in any application that will draw more then three or four amps I put in extra grounding when working with 200,000$ boxes last year I would go as far as running a ground cable directly from the battery terminal even equal in thickness to the positive side. (haha funny story I paid a small car audio shop to build me four of these monster cables those guys loved me. I would zing up in my little miata and get these huge cables and they had no idea what I was really using them for lol.)

Alexb

iTrader: (1)

Ya, all of those are way expensive haha. I think the first of those would be to get a new psu. Maybe a smaller one from mp3car.com. I have the m2-atx, I might go to an opus psu or something.

But, first I want to try your ground idea. It's funny originally when I built the system I planned on having a ground from the pc all the way to the battery. I actually did. But about a week later I took it off because people had said have the ground just a few feet from the thing that needs to be grounded. I don't recall there being interference during that week, but I don't know if I listened to the radio at all either. So you's saying like ground the psu at a point on the car, and also run the (-) from the battery to that same point, essentially creating a durect battery ground?

Seems like a good Idea, that is if I am understanding correctly.

Now your idea you mentioned a while back, those bags, do you think those would help this situation or not? Because it is a power line issue.

hoss -05

iTrader: (4)

True it is a power problem however if you had a high end PSU it would filter any noise and interference the car would be giving it as well as putting a stop to any internal RF it may produce.

As far as running a Ground line What I suggested you do in terms that may be a little easier to understand is to keep the PSU grounded as it already is but.... Add a second ground line to that point using a new wire directly connected to the battery.

Yes those anti static bags help. Just look at what they can do for a cell phone! I'm sure you have some leftover bags from any computer part you may have every ordered. Or just go as someone at a small local computer supply store I'm sure they have a ton. Experiment with them put them over your PSU the whole computer or your HU.

The cash for that PSU I had listed earlier is really not a bad price at all for what it is. Any time you get into Good solutions for uncommon problems the price sky rockets dramatically.

you better keep me updated with the results! If I was near you I would give you a hand anytime.

Alexb

iTrader: (1)

Theoretically I should get the same loss in interference I got when I ran the m2-atx from the regular ATX psu, if I were to take the ground from the m2-atx (but NOT the positive) and connected it to the regular ATX right?

essenitally powering it from the car, but grounding it to my house.

If this still sloved the interference issue that would mean it is the ground. But if it didn't then I am pretty much screwed when it comes to cheap fixes?

hoss -05

iTrader: (4)

no you are still not screwed. There are still ways to control RF. IE you could pick up a metal electronic project box from Radio shack. You can use try and use static control bags. Try and limit the RF that can be passed to the cab through the trunk.

You can also use one of those line input stabilizers that I had mentioned earlier.

hoss -05

iTrader: (4)

Bump