Tony Sivori wrote:
On Sat, 09 May 2009 16:08:51 +0100, Arfa Daily wrote:

The current rating of the power supply is unimportant - sort of - as
long as it is at least enough. I say "sort of", because it depends on
whether or not the supply is regulated. If it is, then it doesn't
matter how little, or how much, up to the rated current level, that
you draw from it. The voltage will remain at 9v give or take. If the
supply is unregulated, then the chances are that it will be rated at
9v nominal, only when it's loaded close to its maximum. At lower
currents, the voltage could well be 20% above that, particularly
with small transformers which are notorious for poor load
regulation. So the output could easily be up around 11v when lightly
loaded.

Your bark trainer might well tolerate this, even though it represents
getting on for 100% over-voltage, but it is a risk that I don't
think I would want to take for the sake of shelling out the small
amount that a suitable 6v regulated wall wart would cost.

Thanks for that. Sometimes I am too cheap for my own good.

I have good luck finding wall-warts at certain thrift shops, FWIW.