Hi guys,

Recently I boutght a second mp3player/walkman/laptop fm transmitter to
be able to transmit music from my laptop in the house to a radio in the
backyard. Just like the first one it does not sound good (this one is
being returned).  Both transmit like they should, but the sound coming
out of the radio speakers is really low, which leads me to believe that
there is an impedance mismatch between the laptop's output and the
transmitters input.

The laptop's specs from the manufacturer do not list the output
impedance anywhere and the manufacturer's web site was of no use for
this either.  Googled for the same information but I did not find
anything reliable as far as this info is concerned.

Does anyone know what is the typical output impedance of a laptop's
headphone jack?  The only usefull info I have found is that the majority
of these jacks will put out 1v rms.  Also, not being knowledgeable in
analog electronics (I do fine in with digital electronics though), can
anyone help me out with coming up with an opamp circuit that would take
care of this impedance matching?  Since this is for home use, I thought
that a couple of opamps (1 left and 1 right) could take care of it with
either a 9v battery or a simple power supply.  This would plug into the
pc headphone jack and the fm transmitter would plug into it.

Thanks in advance.


-Mario


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