[NTLUG:Discuss] OT battery substitute

[Brian Koontz]

On Sat, Apr 30, 2011 at 03:36:20PM -0500, Levi Darby wrote:
> A 6v adapter should be fine.  Just make sure not to use too high of
> current.  I don't recommend going higher than 400 mA though.

The adapter will supply the current needed for the device, so you'll
want an adapter rated at a current higher than the draw of your
device.  Keep in mind that a 6V adapter will read 6+ volts "unloaded"
and then sometimes drop quite a bit under load. There is an off-chance
you're running an adapter that doesn't meet the current requirements
of the device.  If that's the case, the voltage will drop quite a bit,
which could cause the problems you're seeing.

You should be reading the adapter voltage while it's under load,
plugged into the device.  

BTW, the hum you hear is RF interference from the AC side of the
adapter.  You can try finding an old iron toroid or power line filter
and wrapping the output line a few times around it.  Wall warts are
cheap and cheaply made.

  --Brian