"Larry W4CSC" wrote in message
...
On Wed, 17 Sep 2003 16:15:22 +0200, "Meindert Sprang"
wrote:


Sorry Larry, your explanation is way off. The inverter, being a square
wave
one, doe not produce spikes like an ignition system. Also, the squarewave
does not produce induction spikes in the connected adaptor.

Ok, bright boy, how DO we keep a cheap wall wart transformer made for
a sinewave from inductive kick when the square wave switches? Ever
time that square wave switches there WILL be a HEAVY pulse when the
core field collapses.

No, there won't be a heavy pulse or "inductive kick". An inductor will
resist a change of current by releasing a current in the opposite direction,
caused by the collapsing or changing magnetic field. On an open coil, this
will lead to a high induction voltage. On a loaded coil it will not. The
induction current will only work against the current from the source for a
short time (exponential curve) resulting in a triangular like current when a
square wave voltage is applied. Please brush up your theory or go read a
book about switch-mode power supplies.

It doesn't come from the inverter....it comes
from the wall wart transformer.

The OP's question was about a laptop charger, which is very unlikely to have
a primary transformer.
It will be a switcher.

If his power supply is a switching
power supply, it really won't make any difference as there's no AC
transformer and the input rectifier will simply absorb any waveform
fed to it to charge the HV caps.

Exactly.

The only thing that might destroy a
switcher is if the rectified square wave causes overvoltage on the HV
filter caps on its input rectifier.

If the peak-peak voltage of the square wave is the same as the sinewave, it
won't make a difference. A square wave with the same RMS voltage as a
sinewave will even have a lower PP voltage.

Meindert