On 14 Dec 2006 23:57:35 -0800, "w_tom" wrote:

mm wrote:
I have a 2 inch Sony Watchman tv that runs on 4 AA batteries. I want
to use it in the car during a trip this spring.

Is it better to buy a "power supply" that plugs into the cigarette
lighter and generates 6 volts, OR

to run it with 4 batteries, measure the amperage, calculate the
effective resistance of the TV, and then make my own power supply that
plugs into the cigarette lighter, that would consist of a plug, a
jack, a wire and a fixed resistor. The resistance of the resistor
would be the same or nearly the same as the calculated different of
the tv.
...

Are you familiar with load dump?

No, I'm not. I googled load dump and read three of the sites, but I
picked wrong I guess and didn't learn much.

ISO says that voltage can be 270
volts. SGS Thompson defines it at 80 to 100 volts. Your design will
make load dump irrelevant. Cheaper inverters hope you never learn why
they are cheaper - while forgetting to include load dump protection.


If you are inclined to email me
for some reason, remove NOPSAM :-)