Hi RATs,

both projects I have on the bench at the moment
have a larger dynamic (read power) range than the
first amp I utilized magic eyes (for merely the
nice look of them when flickering).

You can see the circuit I used in the little
amp half way down the page at:

http://www.ndh.net/home/schlangen/ro...aten/em80.html

Useful reading range voltage at the grid of EM80 is
between 0 volts (shows thin line) up to ~ -18 volts
(full reading).

It is nearly impossible get a reading at normal
listening levels whatsoever from the magic eyes
when the max. reading (-18 volts at grid) is
adjusted for max. reading at max. output power
for a stronger amp.

A simple switch and a voltage divider gives a
"sensitive" range for low amp output levels
and a range for higher output levels, but
having to switch the ranges manually is not
practical.

Adding a zener so that at least the EM80 isn't
overdriven isn't optically nice and practical
either, since there is no change in readout up
from a certain amp output level.

Does some have an idea how to implement a
Real Simple (!) sort of dynamic range compression
or AGC, without making things too complicated?

At most I would dare to add one double triode for
_both_ EM80 present (one additional triode system
per channel).

Any ideas appreciated,

Tom

--
Live is too short to be taken seriously.
- Oscar Wilde