There is a definitive math formula for the parabolic curve as used in a sat dish.
I really dout the quality or even validality of using a common bowl.
At summer camp I had my scouts build hot dog cookers with an aiming device. I would like to see a common household bowl cook a hot dog using the sun's energy.
Maybe a sat dish would be hard to aim but thats an easy fix.
I looked at the links posted and the amp with a bandpass filter looks ominious as well as out dated. A preamp using descrete componets?? Wonder how old that schematic is?
Plan is to use a simple LM386 or maybe a 7w chip amp I got from electronic goldmine
(G14042
and add a preamp using an op-amp.
One of the links suggested using a speaker in place of a mic. need to test this out but should work but better??
As for the bandpass filter, not really sure I need but?
going to simulate using TINA as soon as I get MY computer rebuilt motherboard went south)
Hopefully demonstrate to a bunch of young boys (cubscouts) what a parabolic dish / curve is as well as build some hot dog cookers.