[sdiy] protecting line level inputs

[Czech Martin]

An efficient input / output protection has two
elements: a series resistor to limit the current (thus Joule heating
of small semiconductor areas or clamps) and after that clamping elements, like diodes,
zeners, thyristors, transistors ...
that limit the peak voltage (gate oxide breakdown, junction breakdown
because of too high voltage, not current).

Both is needed. The application demands certain values, e.g. an output
resistor has often to be lower value than input resistor.

The problems of such protection circuits are
-add some noise
-some distortion
-lowpass for very high frequencies


For audio it should be possible to always find a very robust solution.


m.c.

-----Original Message-----
From: owner-synth-diy at dropmix.xs4all.nl
[mailto:owner-synth-diy at dropmix.xs4all.nl]On Behalf Of modraj at msoe.edu
Sent: 20 October 2004 15:33
To: synthdiy at sdiy.org
Subject: [sdiy] protecting line level inputs


SynthDIY:
I have determined through experiment that my mixer does not like +/- 15
volt spikes (because now it's broken).
What's the best way to send signals from prototype circuits (like a random
spike generator) to a line level input (zener diodes, pre-amplifier)? What
is the maximum +/- voltage that these can handle?
- Justin