[sdiy] output jack current limit (was 1/8th inch questions)

[John Blacet]

Of course, there are more  points to be considered (I told you it was
not simple...).

The resistor current calculations are correct but they assume an
infinite source of current; a situation that should not be present on
any jack of a modular. In fact, the worst case scenario *should* be two
op amp outputs connected together via two protection resistors.

Op amps also cannot supply infinite current nor can they swing the full
15V supply. So the worst case scenario might be one amp at +13.5V and
the other at -13.5V. In most real world situations, you will not see
such extremes nor will the outputs be DC. They are just as likely to be
audio.

There are cases where you are using logic in the output stage. Here is
where I'll really want a 1K to 2.2K resistor.

In the final analysis, a little time on the breadboard with your op amps
of choice and a DMM set to measure current will give you a better idea
of what *really* goes on in the "protection racket"!

--
Regards,
--/////--
John Blacet
Blacet Research
http://www.blacet.com