[sdiy] impedence stuff???

[harry]

OK... yes. IF the unit is battery powered... or powered from
an isolation transformer (like a wall wart) there is basically no
danger.  Then just provide the speaker load impedance...and
a voltage divider.... an maybe a DC blocking cap if necessary.

But DON'T do this with a high voltage amp....

The other problem is that SOME toys have a bridge output stage...
in that case there is no speaker "ground" terminal.  If I knew that I
would tap the circuit before the power amp stage.  My main concern
was with the bridge output case....

BTW Class "D" amplifiers are becomming popular... here you will
NEED an inductor as part of the load... to form a lowpass filter.
Again... I'd start in front of the amp... NOT the speaker terminals.

Look for the amp... get the chip number...check the data sheet.
Usually the schematics are copies right out of the book !!!

H^) harry

Darren Reid wrote:

>  "harry" <harrybissell at prodigy.net> sez:
>
> > >  speaker level to line level
> > >
> > > Danger Will Robinson... I would only do this using a transformer...
> > > Put a resistive load of suitable wattage on the amp... then a
> > > voltage divider and a small transformer... them run the other end
> > > of the transformer to the line input. You might need resistors on
> > > that end as well.... Connecting directly can blow an amp or mixer
> > > easily. You may want to buy a commercial unit here... that transformer
> > >
> > > is probably not gonna come cheap anyway...
>
> You need some background here, Harry. I suspect our friend Jim is, in this
> instance, modding toys by removing the speaker and inserting a jack. He's on
> the benders list :)
>
> I'm betting that doing that on a speak'n'spell or a Casio SK1 is not such a
> big deal. Now, removing the speaker from my guitar amp on the other hand...
>
> -Darren
>
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