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Phil Allison[_3_] Phil Allison[_3_] is offline
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Default Overvoltage protection


"Alex Pogossov"
"Phil Allison"

But what is the load is not connected? Then the huge magnetisation
energy


** Why huge ???

If Lp is say 100H and Ia = 0.1A then how many Joules is that ?

Apparently 0.5J.



** IOW - **** all.

Even the smallest Varistor you can buy will absorb it with ease.

Like this one for $ 1.58 + gst

http://au.element14.com/epcos/b72205...9?Ntt=100+4399

Agree, it is no problem to clamp the surges, but the point is: why I have
not seen varistors across the OPT primaries in various schematics?



** Cos the usual RC network suppresses the spike sufficiently, along with
the load.


Or is the assumption that no one will be changing tubes on a working amp?


** Well, not with no load connected.


Or occasional arcing and sparking is not a problem?



** The Aussie made 6V6GT used in my first valve amp liked to spark
internally with no load.

Never did it, the A&R OP tranny or the socket any permanent harm.

But if you wanna go belt and braces - fine with me....

BTW - how much HT have you got ??


..... Phil