Questions for Pete

[MD Willington]

Pete.

Have you ever designed or heard of any power supplies that use power entry modules ie IEC Inlet filters on the IEC connector of an ATX power supply?

Do they make a enough of a difference to add one to a power supply?

These are the modules:

http://www.tycoelectronics.com/prodnews.asp?id=598

http://www.cor.com/Series/IEC/EAHEBH/

If they make a significant difference, I'm thinking of maybe building a box in a module to put before the power supply.

Thanks

MD

[PeteS in CA]

Re: Questions for Pete

Radiated EMI is witchcraft, and conducted EMI is divination.

It's too complex to give a good answer. Depending on the switch frequency of the P/S and what ever filter components it has, you could get a moderate improvement in the conducted noise, or you could make things worse. It's a fairly simple filter you're looking at, so an improvement is more likely, IMO. However, the chance of making the radiated noise worse is pretty high. About the only way to know is to try it and use an AM/FM radio and a TV to see if the interference gets better or worse (assuming you don't have an anechoic chamber and $20K - $40K of equipment handy).

[larrymoencurly]

Re: Questions for Pete

I don't think you'll notice an improvement if the PSU already contains a line filter. I had two PSUs with no filters at all, and they completely drowned out AM radio reception, even 20 feet away. But after I added an IEC filter to one (http://static.flickr.com/41/75125024_161da61ad7_b.jpg ) and the missing chokes and capacitors to the other (circuit board had empty spaces for them), radio reception became very clear.

[Per Hansson]

Re: Questions for Pete

That special built Seasonic 350w PSU I posted about has one of those, since the PSU is in the front they have to have a powercable leading to the back of the case...



Most PSU's have a filter on a small PCB right next to the power socket... The other Seasonic PSU I have has one of those...

[MD Willington]

Re: Questions for Pete

Well I do have access to a chamber, but it is strictly ! hands off !

I asked because I've seen this done with radios and such ans some of the equipment we make has them with the slow blow fuse.

Thanks for the info guys!

MD

[kc8adu]

Re: Questions for Pete

since i service commercial 2way and ham gear i have a service monitor/spectrum anylyser.
i find that lots of cheap crap gives off illegal amounts of rf.worst one was a old regency scanner that was radiating on 145.110 so strong it hetrodyned badly with the local wide area repeater i frequent.
found it in a transmission shop up the street.when i turned it off the fm radio they thought was dead started playing!it had a big spur at 104.7 that jammed up the radio.