Homebrew PCBs

On Sat, 19 May 2007 10:31:53 +0200, Tony Smith <ajsmith@...>  
wrote:

>
> The ones without a turntable have what's called a 'stirrer' up the top.
> It's just metal fan in front of the magnetron that bounces the waves  
> around.
> I've seen exactly one one these.
> I'm not sure why domestic oven use rotating turntables (price,
> reliability?).  I think commercial ovens still have stirrers as it means  
> the
> handles on the containers you put in will be in the same spot when you  
> open
> the door.  Some domestic ovens will rotate the turntable to the 'starting
> point' to get the same effect.
> Tony


I have seen three with stirrers, usually the larger ones have them but i  
also have a very small very early oven with one.

IMO the superior method over the turntable, but a bit more tricky  
technically.
One i looked into used a plastic ball bearing (just like metal only clear  
balls). I suspect the metal ball bearing would cause arcing and wouldn't  
work. The stirrer was powered by the cooling airflow (so the friction  
needs to be low).

ST