On 14 Feb 2007 15:45:38 -0800, "Redbelly"
wrote:

On Feb 14, 6:25 pm, wrote:
If the voltage is insufficient, no power supply, no matter what current it
can deliver, will light the bulb.

Oh, really? Let's see the explanation of that.

He's correct. It's simple electricity 101.

OK, fine -- explain it.

A power supplies current draw depends on what the load is
and what the voltage is.

The current draw is not determined by the rating of the supply.

FYI, that's only true if the required current is less than the rating
of the supply.

If the required current is more than the supply's rating, then actual
current IS determined by the supply.

Yes and no. When you draw more current than rated three things can
happen.

1. The supply goes over current until something burns up
2. The supply shuts down electronically (the voltage goes to nil)
3. The voltage diminishes slowly as resistive losses in the supply
use a higher and higher percentage of the voltage drop.

In any case the supply limits the current by limiting the voltage at
the output.