Flyback X'mer Clamp RCD Configuration question

[Magnethicc]

Hello Everyone,
In the RCD Clamp of a flyback x'mer I often see two variations:

I can see they both operate the same but I was wondering if there is any differences between the two configurations of the diodes?
Thank you.

 

[KlausST]

Hi,

They are exactly the same.

In a series connection the order of connection does not matter.

Klaus

 

[cupoftea]

Same, but use the Right hand one, as you have a nice rail to hook scope (or diff probe) "ground" on to when you look at the rcd clamp capacitor voltage...always try and have your scope probe "ground" hooked to a quiet node, rather than a switching node, if possible.
Also, theyre both missing a bit of series resistance, in series with the diode...and of course, neither is the nice RCDZ clamp....which is good for light load power reduction

 

[Magnethicc]

Thank you for your answers.
Why do we need the series resistance with the diode?

 

[cupoftea]

to reduce turn-ON spike seen by FET