Am 11.10.2012 20:31, schrieb Dwayne Reid:
> At 10:26 AM 10/11/2012, Alexander Winnig wrote:
>
>> First: Which voltage level should not be exceeded between both
>> microphone cables(Signal and Mass) *between *a telephone handset and
>> it's telephone?
> What kind of telephone?  Is it an old-school telephone with carbon
> microphone or a newer unit with electret mic?
It is a siemens euroset 2020 so propably electret.
>> Second: I have two AC signal sources with a maximum voltage of 1.2 Volts
>> each. Which circuitry is the one with the least amount of components
>> that combines them in an adjustable way without distorting them or
>> diminishing the overal volume?
> Balanced or un-balanced?
It's the output of the headphones connection in front of a computer. As=20
they are stereo I wrote "two ac signals".

>   If unbalanced, simply use a 1:1 isolation
> transformer connected to one of the signals (primary), then connect
> the secondary of the transformer in series with the other signal.
>
> If balanced, you need two 1:1 transformers.  Connect each input
> signal to the primary of one of the transformers, then connect the
> secondaries in series.  This output signal can be treated as either
> balanced or unbalanced - your choice.
>
> If you can tolerate a 6dB loss, simply sum the two signals through a
> pair of 2k2 or 4k7 resistors.  The mid-point of the resistors is the
> sum of the two individual signals.
Please draw that.

Alex
--=20
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