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this is a 4 input stereo mixer, bearing the original design of Mr. Ray Wilson from MusicFromOuterSpace. It is powered by a bipolar power supply and is able to combine audio from various sources into one output.
in the schematic, I chose to use 5-pin 3.5mm headphone plugs. The extra 2 pins short to ground when an input is not in use. The 3pin header is optional, it is there to generate holes with common spacing for wires. One may use JST-XH (2.54mm) for a modular approach.
the 3D rendering does not show potentiometers because the software does not have a 3D model for the specific ones I chose. Holes will be placed to vertically mount through-hole resistors for those unsure of soldering SMD components.
partially related to the synthesizer rabbit -- one of the hungrier types -- 2 revisions were built on perfboard --
the use of a bipolar power supply is required
a [passive] bass guitar is successfully amplified along with the audio signal from a PC. very neat being able play [bass] along with music by simply adjusting knobs of either source. no more messing with switching inputs or adjusting volume [physically and virtually] at different locations -- they're all there, with a master volume right above (the ZK-AS21)
quality audio potentiometers are recommended -- primarily because our senses do not perceive on a linear scale, secondary to the quality of mass production items which may exhibit scratchy noise when turned. [they'll eventually do this with age] humidity may cause this effect as well.
it is also not limited to 4 inputs -- you can add just about as many inputs as you'd like, and control each individually.
in addition to [bass] guitar and music streaming on PC, having television audio [regardless of input], PC notifications, and the option for additional input sources all through the same set of speakers is liberating, to say the least.
on the second revision, 2 outputs are used -- 3.5mm headphone and standard left and right (white and red) RCA phono plugs. either can be used individually, or both simultaneously [which is the purpose]. the pots are somewhat too close for immediate liking, but needing to cram every thing on that particular piece of perf board was the priority.
ive a board ready to be made, tho currently need specialized tools before fooling around.
after many adjustments, redesigns, and full on rebuilds on perf board -- perhaps the final layout sits and awaits to be made.
although it is quite similar to what is seen here, there are a few differences.
for example, the second 3.5mm input has been changed to RCA phono type L and R, along with the addition of output being either 3.5mm or RCA phono -- even both could work.
a 'master' volume was/is being considered, but that would be 3 volume controls given the current setup.
a grossly overlooked feature was also added -- mounting holes.
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