There's quite a few, off the shelf, 7 or 9 pin SIP devices that are
basically for automotive radio outputs, being 2 inputs and 2 low Z outputs
that operate directly from 12 to 15 volts DC. External required components
are usually 3 to 5 pieces for decoupling and feedback/gain control. Cost is
in the $5 range or less.
Or Radio Shack has some small amps for that purpose that are in the $20
price range.
73
Bob, K4TAX
----- Original Message -----
From: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
To: <tentec@contesting.com>
Sent: Wednesday, January 16, 2008 10:25 AM
Subject: Re: [TenTec] Heil headphones
> On Wed, 2008-01-16 at 04:42 -0800, Dennis OConnor wrote:
>> So far I have not seen anyone offer a circuit for an audio breakout box
>> which will have an audio amp(s), volume control(s), and jacks for 2 or
>> more headsets with their microphone circuits... This would be really
>> handy for lots of rigs, and for visitors to the shack to be able to don a
>> headset and listen or operate also.. Also, very handy for a teaching
>> situation where new ops are being introduced to contesting... I have idly
>> made a beginning on this circuitry in my head, but being truly lazy I am
>> waiting for someone else to offer a debugged and working circuit for me
>> to build..
>>
>>
>>
>>
>> denny / k8do
>>
> Start with a convenient audio output IC, maybe a vintage LM380 or LM384.
> Add the controls to the input of the schematic on the data sheet, add as
> many jacks as desired and its done. Hardly worth drawing a picture,
> nothing unique enough to need fancy artistry. Could be extracted from
> any receiver project in most any recent ARRL Handbook. Such as figure
> 22.48 in the 2002 ARRL Handbook which has multiple inputs for one output
> or 22.56 that has multiple outputs (mostly low level) from one input.
>
> Or look for a computer speaker amplifier an add a forked output cable
> with multiple headphone jacks. Off the shelf and probably ready to work
> though some may not like having a transmitter near them.
>
> 73, Jerry, K0CQ
>
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