power supplies with minimal radio interferance?

**Mickz** · 02-13-2013, 03:19 AM

All feed-through caps have a solid wire straight through the centre, usually with a solder eyelet on each side.

The wire is encased by the capacitor which is connected to ground (the case) The action of the wire passing through case via the parallel connected capacitor causes any RF on the wire to see a low impedance to ground. RF is bled off the wire and coupled into the inside of the case. There is no way for the RF to bypass or radiate around the cap. This is not the case with a toroidal choke or ordinary bypass cap method where sharp rise time noise can couple around normal bypass methods and continue to travel down and therefor radiate from the cable.

**johnjore** · 02-13-2013, 03:28 AM

eh.. sorry, this is a crash course in caps (electronics) for me.

I'm still confused as to where the two ends of the wires are connected and to what. In my previous post, I added a picture showing where I think they are connected.

One wire enters from the right and is soldered to the tip of the left as per you post (the red).

Where is the 2nd wire soldered to the cap?

JJ

**Mickz** · 02-13-2013, 03:39 AM

No problems, RF is totally different to DC and audio. A piece of wire 1/16 of an inch long can look like an open circuit at high RF frequencies.

In a normal FT cap there would be a solder end at each red mark (either end of the cap) This is a straight through wire connection but cemented into the cap. Those red marks you show are physically on each side of the PCB. In you case with these caps you have to put a single wire going through the cap and soldered it at one end. You now have two connections, physically one either side of the PCB passing through the cap.

**johnjore** · 02-13-2013, 03:57 AM

Oh. The light-bulb just came on. Maybe.

Like this picture:

Name: final.png
Views: 66
Size: 2.16 MB

JJ

**Mickz** · 02-13-2013, 04:04 AM

Yes, remove some insulation from the wire where it needs to be soldered and when you solder it to the cap make sure you solder it completely around the wire, no gap. You could use long cables and terminate each end at the correct length, would make a tidy neat install.

**johnjore** · 02-13-2013, 04:12 AM

finally there. Thanks!

JJ

**Mickz** · 02-13-2013, 04:19 AM

No problems, glad I could help in some way

**ibf** · 03-02-2013, 07:41 AM

@John

Any luck with the mod? Im curious how much improvement it would make.

Thanks

**johnjore** · 03-02-2013, 09:42 PM

I finally completed the build this weekend, but ran into a problem during testing.

I can turn the computer on and enter BIOS configuration and leave it there. All good, even after 30min its still in the BIOS configuration screen. No crash, no problems.

When starting Windows, it resets during boot. After autologon and during init of the various bits and pieces, the computer just resets, as if I had pressed a reset button.

Tried using an old ATX cable and it boots fine so the mod is causing the problem. But what?

JJ

**Mickz** · 03-02-2013, 10:21 PM

The only things I can think of are a poor cable connection or the gauge is too small or too few cables to carry the current for a higher CPU load during the boot process.