REFLECTOR: DC power adaptor

John Dibble aminetech at bluefrog.com
Thu Nov 13 16:29:55 CST 2008


Dave, Andy,

I'm looking into your suggestions.  I measured the current at 40 ma and calculate a
resistance of around 12 ohms for 0.5V.

FYI, the problem is that the headset doesn't cancel the low frequency noise and in fact
amplifies it.  It's actually quieter if I take the headset off.

If ground is the issue, is there a way to isolate the ground?


John


Dave Philipsen wrote:

> John,
>
> My guess is that the problem is not with the voltage.  Even though your
> adapter is putting out 3.5 volts it probably isn't that far out of
> tolerance for the headset.  A pair of new alkaline batteries may
> actually present a voltage a little higher than 3 volts also.  I'm
> thinking you may have a problem with isolation of the supply voltage.
> The Zulu headset may not like the fact that the ground of your 3 volts
> (3.5 volts) is at the same potential as the ground of your mike and
> headphone plugs.  To test this out, simply power your Radio Shack
> adapter with a 12 volt battery that is not tied in to your aircraft.  If
> it works, then you'll know that the ground isolation is the problem.  In
> fact, I saw an advertisement somewhere the other day in an aviation
> magazine for an isolated ground power adapter for just this purpose.
>
> John Dibble wrote:
> > I use a DC power adaptor from Radio Shack to power my Lightspeed 30 3G
> > headset.  I recently upgraded to the Zulu headset and find it won't
> > operate properly off the power adaptor.  The power adaptor puts out 3.5
> > V which is higher than the 3.0 V on its selector switch.  Apparently the
> > Zulu requires more precise voltage.  Is there an easy way I can reduce
> > the voltage to 3V?
> >
> > John
> >
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> --
> Dave Philipsen
> Velocity STD-FG
> N83DP
>
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