James,
There was a homebrew headphone mixer in the ARRL Handbook sometime back
- simple, with op-amps to isolate the sources.
However with the advent of 2 to 5 input mixers being available in the
$20 to $60 range (see Amazon), it seems foolish to consider building
your own - drilling the enclosure for the potentiometers and jacks,
building the board, mounting things, etc. will take more time and effort
than is reasonable unless you really like doing those things - and it
will likely cost more than buying one already built.
The nice thing about a mixer is that you have control over the level of
each input as well as an overall output volume control.
73,
Don W3FPR
On 1/9/2019 6:03 PM, Richards wrote:
Good Day.
Background:
I am assisting a blind ham who also suffers some hearing loss. I
suggested using headphones to attenuate ambient environmental noise as
he operates. The rub is, he needs to hear both his receiver AND his
computer (which provides audible feedback when logging contacts and
performing other duties.)
Question:
Can anyone suggest a simple passive (or active) mixer circuit schema I
can build for him to safely mix audio signals from his transceiver
headphone jack with audio signals from his computer sound card headphone
jack?
Discussion:
While there are multiple commercially produced simple and complex mixing
products in the marketplace, I would prefer to build an inexpensive,
small footprint solution we can easily incorporate in his station to
minimize clutter and the number of cables, jacks, and controls -- he
contends with plenty of that already. I suppose one solution might be
a simple Y-adapter cable, but that seems too easy and I wonder whether
we should isolate the signals and/or grounds in some way? (e.g., I do
not wish to cause any "Pin-1" grounding issues, and etc.)
Any traction? Can anyone point me to an appropriate circuit schematic
or other resource? I don 't mind doing homework, and while I enjoy
building stuff and I am familiar with the basic concepts involved, I
could use a leg up on this project, especially to keep it simple and
easy to build and implement. Please reply off list if this question is
too far off topic, although I suspect there are many hams who might be
interested in the result, besides similarly situated disabled operators.
Thank you - James - K8JHR -
---------------------------------------
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