[Phys-l] YouTube Inquiry (was Students' READING...)

[Brian Whatcott <betwys1@sbcglobal.net>]

Julie Quah wrote:
> ...kids nowadays are born into the MTV era, seeking information by watching  
> Youtube...
> Julie from Singapore
> Sent from my iPhone
>   
Which reminds me...the other day, I was googling idly using DIY as a 
search key,
and stumbled across a home-brew spot-welder on uTube.

There was a short movie showing a transformer with a few turns of thick wire
leading to two brass probes, which neatly demonstrated joining two 
pieces of steel sheet.
Spot welding is a favorite tool of home brew jet engine makers, it seems.

At any rate, within the span of a one or two minute movie, I saw that 
the popular approach to making one of these devices is removing the 
transformer from a discarded microwave oven and excising the high 
voltage winding, which is typically set in a separate core window. When 
this is removed, #2 welding cable or slightly thinner cable will neatly 
fill the winding with three turns whose terminal voltage is then 3 volts 
or a little more.
The considerable current neatly heats a small 1/8 inch diameter  which 
fastens
thin steel sheets together.

Even more astounding, was to see the youngsters who had acquired a 
"pole-pig" - i.e
a step-down transformer to be found on utility poles.
Driving this from the low volt (120 /240 volt end with a ballast) they 
would then demonstrate pulling a four inch arc from the long insulated 
Utubehigh volt electrodes on the pig, with a wire on a long stick.   
There were numerous examples of this "toy"....

Now THAT'S inquiry!    :-)

Brian W