On Feb 26, 7:05*am, Doug White wrote:
"Michael A. Terrell" wrote innews:tZSdnXJtHfgz39fSnZ2dnUVZ_jSdnZ2d@earthlink. com:





Doug White wrote:

These things were also sold under the Advent and Radio Shack name.
They run on 900 MHz. *I have the owner's manual, but it doesn't
include any repair info. *I actually want to bypass RF and just use
them as battery powered speakers. *I'm sure I could trace it out, but
it would be easier if I had a schematic, and I'm curious about the
inner workings of the RF as well.

* *Do they have volume controls? *If so, you may be able to connect
* *the
audio across the pot. *That is, if it is an analog circuit. *If not,
you'll have to find the datasheets for the ICs and draw your own
circuit.

They do have a volume control, but how useful that is depends on where
they put it in the food chain. Certainly worth a look if I can't scare
anything up.

Recoton also has a large number of patents, and I thought I might get
lucky with one of those. *Unfortunately, a lot of them are unrelated, and
none of them include any detailed schematics (sometimes they do). *The
guy behind Recoton was Larry Schotz, who was pretty creative. *I found
his original patent (4829570) for sending the audio over the power lines
(I had those speakers a long time ago as well). *No real info on the 900
MHz FM wireless speakers. *I may just have to open one up & try to sort
it all out. *If he used a commercial FM decodeer chip, there may be a
clean spot where I can tap into the lines comming out of that. *There is
also a left/right/mono selector switch that would be a likely spot to
inject the audio.

So are they analog or digital? One patent keeps the signal digital
until the very end.

I can't believe he got a patent for analog FM stereo transmission over
AC power lines -- that is an obvious combination of AM carrier current
plus FM stereo multiplex of thirty years previous.