Re: Missile Command audio question

On Fri, 31 Jan 2003 10:51:50 -0600, you wrote:

>Missile Command, unlike most other Atari games of that era, has two
>audio outputs and there are different sounds sent to each channel.
>Summing both channels by directly connecting both output wires doesn't
>work. Should both channels be ORd with a 7432 or something similar?

        Um... no. That only works with digital signals. :)

        What you want is a 2-channel audio mixer, like this:

                       10K
                  ----/\/\/-----
                 | |
         10K | V+ |
CH1 ----/\/\/----O |\ 7| |
         10K | 2| \| |
CH2 ----/\/\/----O---|- \ 6 |
              10K 3|LM741>----O----- OUT
           ---/\/\/--|+ /
         _|_ | /|
         GND |/ 4|
                         V-

        ...where V+ and V- are the positive and negative supply voltages of
your audio amplifier. (Both should be the same voltage; i.e +12V and -12V.
The LM741 can operate up to +/-18V)
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solarfox@DON'TMESSWITHtexas.net (Gary Akins jr.)
http://lonestar.texas.net/~solarfox
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Received on Fri Jan 31 22:05:54 2003