[R-390] Audio Output Transformer

[John Lawson]

On Tue, 5 Oct 2004, Charles B wrote:

> Hi all,
>
> Today I purchased an Audio Output TRansformer from Radio Shack.  It's a 1K 
> ohm center-tapped to 8 ohms.
>
> The primary wires are:  blue, black, and green
> the secondary wires are:  Red and White


   Look at the transformer, or it's box, or (perhaps) the data sheet that 
came with it.  You have a transformer with a 1K Primary, divided into two 
500 Ohm sections via the center tap.

   I don't know if they are following the old RETMA color codes or not - 
but let's say that the 1K winding is the Black and Green wires. You can 
actually test this with an ohmmeter, though the DC values will be 
different from the AC Impedance stated.  If in fact the Balck and Green 
wires are the 'start' and 'finish' of the Primary, then the Blue wire 
should be the mid-point.  It should measure about 500 Ohms to either the 
Black or Green wires.

  So you'd hook up the Blue wire, and either the Black - or - Green wire, 
(not both at once), to the 600 Ohm output.  Then you attach the Red and 
White wires to your speaker.

  You don't say what wattage the transformer is, (or your Speaker, for that 
matter)...  so if it's a tiny little device it's possible you could blow 
it out with high levels..


   Anyway, the 500 Ohm center tap is close enough (IMHO) to match it.

   If this doesn't work out for you, write me privately off-list and I'll 
send you a 600 Ohm-to-8 Ohm voice-coil unit that will do the job.


   Cheers

John  KB6SCO







>
> Input is 1 K ohms
> Output is 8 ohms
>
> what's the combination of wires do I need and how will I hook them up for 600 
> ohms?
>
> Thanks in advance
>
> Chuck
>
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