In article , Phil
Allison scribeth thus
Jim Lesurf wrote:


http://www.audiomisc.co.uk/Armstrong...nale/1982.html

I'm now curious that no-one has commented on the contents - particularly of
the 1982 page!


** You mention speaking with Peter Walker about the "crow bar" circuit in the
ESL63. Here is a schem for an early version.

http://www.quadesl.com/schematics/quad63_schematic.gif

The triac used is a T6000B, rated at 16 amps continuous and 150 amp surge for
10mS. Other units use a T2800B, rated at 8 amps with a 100 amp surge rating.

Later ESL63s, from 1989 onwards, used a TIC216D, rated at 6 amps with a 50 amp
surge rating.

http://www.euronet.nl/users/temagm/a...ematic_new.jpg

As the crow bar is intended to clip transients that exceed the voltage limit of
the panels and only to be used with amplifiers that have electronic current
limiting, any of the above are more than adequate.

Large amplifiers with no current limiting are warned against, but if used could
fry the smaller triacs or the 1.5 ohm 5W resistor in series. Later models also
had a circuit breaker in series.

In any case, the speaker itself was protected, because triacs invariably fail
short.


.... Phil



Quite the case!. Has anyone had problems with nearby mobile phones
tripping the protection crowbar as mine seem to be very sensitive to
that sort of signal?.

--
Tony Sayer