Jim Weir- need help on aux audio inputs to PM-3000 intercom

Jim,
Many thanks for pointing me in the right direction.
Danny

RST Engineering wrote:
"E Pluribus Unum" (backside of the dollar bill; "Out Of Many, One")

The basic idea is to take each output, terminate it in a resistor of the
impedance it "wants" to see (generally a 560 ohm resistor to simulate a
standard 600 ohm load), the run all the outputs through an isolation
resistor to a summing amplifier, possibly through a switch to turn each one
on or off as desired, and then the output of the summing amplifier into the
COM input of the intercom. I'm very surprised, though, that the intercom
doesn't have an "aux" input other than the music input.

I can't describe a summing amplifier in words without pictures. Anybody got
a lead on a binaries group where I can post a picture of what I'm talking
about?

Or, go to www.rstengineering.com/kitplanes and look at U101 in the August
2002 article for an idea of what I'm talking about.

Jim





"Danny" wrote in message
oups.com...
Hi Jim,
Thanks for taking the time to answer. I respect your opinions so OK, I
can live without stereo and install a PM-1000 that I have but what is
the best way to interface the aux audio input into a system that does
not provide for any other inputs other than COM from the radio and a
music input. I know I can use the music input but this gets muted
anytime someone speaks.