Mr. McMahon,

Actually my electrical interest is near the 3.3V and 5V. Once i had played
with 1.8V for low-power ASIC design purposes. But now the situation is
completely different. I had designed led strip board. Which is 50cm and
contains 18 leds on it. Each strip drawns 60ma dc current and in total there
was 42 x 60ma ~ 2.5A current requirement. Led strip has been powered on 24V
- 4.5A smps. When i layed the strips to the ground i've noticed a short
circuit on the line while i was testing the system. After examined the
system carefully i've noticed the source short circuit. Then i've seen the
sparks and feel the scent of sparks. Luckily nothing happen to any led.
Thats the story behind my curiosity.

Besides, i've seen some people who test the existance of mains by making
touched the active lines to eachother. After reading your answers i will
tell them how bad is that before they have burned themselves.

The worse is there are electric techinicians that uncover the 380V cable
while the line is active.. But still living. Actually i have to say that
they are living on a razor's edge :)


Last but not least, i have a 100Mhz analogue German made scope. Can i touch
the probe directly to the mains line or should i use a cap for the
protection of the scope's input?

All of your comments are very appricated.

G=F6khan SEVER.







On 5/22/06, Russell McMahon <apptech@paradise.net.nz> wrote:
>
> 1-) Why do sparks exist when we make touch the (+) line to the (-)
> line of
> dc voltage or (phase and neutral line of AC)?
>
> Heated/vapourised material from conductors.
>
> 2-) Where is the source of scent after touching the two lines to each
> other?
>
> Ozone - oxygen in air changed from O2 to O3. Also possibnly material
> from heated conductors or insulation.
>
> 3-) (Although this one is a bit foolish question) Is it wiser to test
> the
> existance of the electricity on the AC line by letting touched phase
> and
> neutral lines?
>
> No!!!
>
> ie Neutral won't tell you anything IF it is properly functioning and
> may turn out to be as lethal as Phase if things are not as they should
> be. use a meter !!!!!!!!!!!!!!!!!!!!!!!!!!!!
>
>
>        Russell McMahon
>
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