PSU Ringing

[Kashmire]

I have a high-current power supply for my Zen amplifiers - 2 channels operating at 2A each, for a total of 4A. At first, I was using a choke-loaded diode bridge (otherwise known as choke regulation). I use the choke to improve power factor and lower peak currents - sure, output voltage is lower, but peak currents are dramatically reduced (it is also dangerous - if the load is removed, the voltage shoots up!). I'm only using 3 to 6mH, so it's not into continuous conduction.

I bought a 66 volt Avil-Lindberg transformer from PartsExpress. It's a great deal! After the choke, I get about 50V. I have both channels on the same PSU, so that if one channel fails, the second channel continues to load the choke (choke-loaded power supplies require a load to regulate voltage).

I had a horrible ringing in the PSU. When the diode turned off, a very sharp high frequency spike would appear. I removed the bridge and made a half-wave using ultrafast diodes from IXYS. The ringing is still there.

It must be the choke loading - as the choke drags current out of the diode, the PN junction slams shut. But since it's not continuous conduction, it's at zero current! What's happening, and how do I fix it? I tried a snubber, but it just resonated with the choke - big mistake!

[Steven]

http://www.diyaudio.com/forums/showt...831#post348831

Steven