[Elecraft] Sorta OT - assistive technology assistance needed

[Don Wilhelm]

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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