F5 power supply...

[HVfanatic]

Hi,

I'm building my power supply, using a standard bridge rectifier.

My question is: Do I need caps across the diodes of the rectifier to damp switching noise?

More important:

Which value is required for this caps, which cap type should be used???

I read of 47n, 100n, even values of only 10-15n...

How do I determine an optimized value in this application? I guess, a Wima FKP could be a good choice there.

Please share your experience!!!

Thanks!!!

 

[AndrewT]

........My question is: Do I need caps across the diodes of the rectifier to damp switching noise?.........

The cap across the diode changes the frequency of the ringing.
The cap does not damp the ringing.

Adding a cap across the diode can make the PSU more susceptible to ringing.

Have you read any of the many Threads discussing PSU snubbing?
Have you seen references or links to Hagerman?

 

[buzzforb]

HVfanatic,
Linear Audio's current edition has an article by Morgan Jones investigating this very thing. It is one of the main reasons am buying this edition. It is probably worth the cost as it will be clearly explained and tested, and this by a guy who likes tubes, so you know sound is important.

 

[HVfanatic]

Hi Andrew, could you post the links???

@buzzforb: I fear, it's just a reprint of Morgan Jones book...

 

[HVfanatic]

I'll start with this: http://www.hagtech.com/pdf/snubber.pdf

THANKS!!!

 

[HVfanatic]

Hi,

I took a look at the Hagermann article: So in the end, I have to measure the inductance of the Transformer, measusre the interwinding capacity, lookup diode cap, divided by 2 (because full wave rectification!), or estimate as 50pF/2(????)

Afterwards calculate values for caps and resistors.

Correct???

 

[HVfanatic]

I have a precise capacity meter: How can I measure the interwinding capacity of the transformer???? Please advise.

 

[HVfanatic]

My idea: Short the primary, and put a well known cap in series with the secondary. Then measure the secondary with the cap-meter and calculate the interwinding capacity...?????

 

[HVfanatic]

If this: Interwinding Capacitance

is the correct definition, I could just take a wire of the primary and a second wire of the secondary an connect them to my capacitance meter.

Anyone who did such before???

 

[Andersonix]

I'm looking forward to trying this method...

 

[HVfanatic]

Hi Andersonix, the method member zigzagflux described is very cool. THANKS!!!!!!!!!!!!!!

 

[Andersonix]

You're welcome! Please let us know how/if it worked for you, as I have not tried it yet.