On Dec 19, 10:16*am, Tony Hwang wrote:
wrote:
On Dec 19, 2:25 am, mm wrote:
On Thu, 18 Dec 2008 18:04:36 -0700, Tony Hwang
wrote:

mm wrote:
How many things do you know of where a voltmeter shows no voltage, but
the device works fine?
I bought an auto/air laptop power supply for a friend of mine, and it
was a good brand (Targus) and it's hard to imagine too high a voltage
coming from a car, but since it wasn't my computer, I thought I should
check the voltage before plugging it into his new laptop.
So, out in the car, I measured the voltage and got zero. *Even though
the light was on on the brick.
does the device have a multi-pin connector i.e. more than 2 pins?

I think that device needs to see a programming resistor to tell it
what voltage to output..

No resistor, no output.

It has nothing to do with series vs parallel regulators.

Mark

Hi,
May I ask what programming resistor is?- Hide quoted text -

- Show quoted text -

if it is like this one

http://www.targus.com/us/accessories_power.asp

it needs a special "tip" for each laptop. THe tip has the right
physical conector and also has some device (probably just a resistor
but maybe a diode) of the correct value to tell the supply what
voltage to put out. It's just a programmable power supply with the
programming element in the tip. They tell you which model tip to use
with each laptop.

If you are not skilled in electronics which appears to be the case (no
offense) then the best thing for you to do is buy the correct tip that
you need for the laptop that you want to use from Targus.

Mark