Thread: power supplies with minimal radio interferance?

that doesn't solve radiated EMI issues though (ex: a portable radio anywhere near my PC would lose signal)

but worth a shot if you think it would fix your situation

i think everyone is going to solve their noise issues in different ways because of their car or install situation.

I bought one and tried it, it was not able to power the visteon
I think that optical isolator doesn't conduct to all pins in the serial.

Well... at least I tried!

I blew my opus and went to a inverter while waiting for my M4. With the opus and inverter my HD radio worked great. As soon as I installed the M4 I got all kinds of nasty radio interference. HD was kicking in and out and analog stations were fuzzy with low reception.

Somehow I found that when I unplugged my monitor the computer shut off. I found later that my case has voltage between it and the ground wire. I then soldered a ground wire from the M4 terminal to the case and it seemed to improve my reception dramatically and now when the monitor is disconnect the computer stays on.

I think i might have some grounding issue (obviously) but i can't quite put my finger on it. Anyway, the recpetion is good enough for now I haven't looked into it. There still some static, and sometimes annoying switching between HD and analog, but I now have a sirius SC-C1 hooked up and althought I don't care for the sound qaulity, at least it's not fuzzy.... I guess the lesser of the two evils.

Anyway, I just thought I'd share my problem and what little troubleshooting I did and might add more later when I figure it out.

Hope that helped...

I fried my old setup while tryin to fix it, and I ended up upgrading to asus Eee laptop with my existing LCD, all interferences are gone now and FM radio is crystal clear!

However the Fob keys are reduced in range now lol

There's a well reviewed voltage booster and RFI filter used by HAMS

http://stores.tgelectronics.org/Detail.bok?no=7

I wouldn't use this as a power supply for the PC, but other sensitive equipment like radios and amps. An interesting feature is that when it's off it passes normal battery voltage.

Gawd - that booster reminds me of some stupid Aussies that reckon you must have a dc-dc converter to charge auxiliary batteries.
But at $300 for 20A and $500 for larger units, I see the temptation for this expensive con - I mean, solution. (As we say, isn't it easier and cheaper to cut (decrease) voltage than increase it?)
But I was told yesterday (in comparing Engel to Waeco fridges) that a battery protector can be bought for $120. I was thinking $20 was more like it.... Of course, that was in Australia....

I had a quick look at this thread after searching for interference caused by the M4-ATX supply.

This supply will completely block all GPS and FM reception in the car.
1: No I am not going to add an external aerial just to overcome the power supply problem.
2: I am in a strong reception area and the PC causes No interference problems, just the M4 PSU.

A laptop with GPS will start dropping satellites when moved close to the car.
A standard GPS will not function mounted on the screen with the M4 powered.
Turn of the M4 and everything is perfect.

Now before I get lots of helpful suggestions, a bit of background.
I am an electronics and communications Tec- I design and program
industrial Microcontrollers systems.

So let’s get to the test. (Simplified description)

1: Removed CAR-PC and M4 supply to the workshop.
2: Fitted a mains powered ATX supply –
The PC with screen and all USB devices causes NO interference.
The PC with case open and FM radio sitting on the HDD cause NO interference.
GPS works inside the shed.

3: Fit the M4-ATX supply in the M4 metal case and power up the system.
The FM radio has no reception anywhere in the workshop.
GPS stops. GPS on Laptop stops.

BTW- The M4 is powered by a 100A RF filtered linear supply.
Yes, also tried a bench battery just in case. Total current draw of the PC is 3.5A.

I have fitted toroidal RF chokes to the 12v leads – slight change.
I have fitted toroidal RF chokes to the ATX supply leads – slight change.
No amount of earthing or wiring configuration change will remove the interference.

This M4 ATX supply is starting to look like a bad joke

No emails have been answered by the maker on this or other problems that I have reported.

Tomorrow, I am going to try a basic 200watt ATX supply, and if it’s sufficiently quite, I
will make and program a micro interface to do everything the M4-ATX is supposed to do.

This unit is being fitted to a 2004 Honda Accord. I have removed the old OEM combined
Audio-HVAC system. I relocated the HVAC PCB and interfaced it with a microcontroller via USB to the Car-PC.
The "climate control system" is now controlled via the PC touch screen
or manually via another “remote” microcontroller interface unit.

Interesting Mickz. And a good report too.

It's sounding like radiated interference. I'm wondering if mesh over the fan vent or other large holes might help. (I'm assuming the case is grounded.)

Higher freq operation could mean conventional housings fail EMI/EMC...
It'd be a shame to fail for interference reasons, but it wouldn't be the first to do so....

Thanks again.

Hi, this is a broad-band noise extending into the UHF region.
I have equipment including Spectrum Analysers that show
this garbage spewing from the M4.

Case coupling is not the problem; it’s bleeding out the ATX supply leads.
It’s unfortunate that the severity and frequency of radiated RF changes with
supply rail variations, which is of course is common with switch mode and
up-switching/converting PSU’s.

This thing would never pass an EMC standard.

I have pondered the possibility of a faulty unit, however I can’t think of any fault that
would could cause this problem yet allow the supply to produce full rated output into a load.

Further tests will follow today in my last attempt to fault find this unit.