Cambridge A75 Power Amp
 

In article ,
Steve Swift wrote:
I'm particularly worried about this effect in the case of the fitted
fridge/freezer that the builder installed in our new house - the 13A
plug is somewhere behind the fitted units, so if that fuse ever
evaporates then we'll have to dismantle the kitchen to get at the plug.

That's really against regs. It's the isolator in this case and should be
reasonably accessible.

--
*The more people I meet, the more I like my dog.

Dave Plowman London SW
To e-mail, change noise into sound.

Cambridge A75 Power Amp
 

In article , Tony Gartshore
wrote:
In article ,
says...
FWIW In the power amp I was referring to, I've used one for 20+ years,
and a second for about 10 years, with no fuse failures.


I was always taught that a transistor was an expensive device designed
to protect a fuse..

That can very easily be the case. :-)

The trick is to understand the way fuses behave and the details of the
current waveforms.

This often means that the fuse value you choose is well below the peak
current levels you are concerned about. Thus in the example I was
describing, the fuses were a 5A nominally 'fast' type. Yet the amplifier
would cheerfully give peak currents well above 30A on both sinewave tests
and music without the fuses blowing. Yet the fuses protected the
transistors from a short. I suspect that 2A fuses would actually have been
fine for almost all normal use, but 5A ones did the job OK.

However, simply choosing 30A fuses would have been a recipy for disaster!
;-

Slainte,

Jim

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