Selectivity ratio and skirt selectivity

Thread starter agalya
Start date Mar 18, 2010
Tags

Ratio

Mar 18, 2010

agalya

Whar is selectivity ratio and skirt selectivity??
what is the -30 dB point??

Engineering news on Phys.org

Mar 19, 2010

berkeman

Admin

agalya said:

Whar is selectivity ratio and skirt selectivity??
what is the -30 dB point??

What is the context of your question? Is this with respect to electronic filters, or some other application?

Thread 'I need a concave mirror with a focal length of 150 feet'

I need to cut down a 3 year old dead tree from top down so tree causes no damage with small pieces falling. I need a mirror with a focal length of 150 ft. 12" diameter to 36" diameter will work good but I can't think of any easy way to build it. Nothing like this for sale on Ebay. I have a 30" Fresnel lens that I use to burn stumps it works great. Tree service wants $2000.

View full post »

Thread 'Questions about the Tesla turbine'

Hi all, i have some questions about the tesla turbine: is a tesla turbine more efficient than a steam engine or a stirling engine ? about the discs of the tesla turbine warping because of the high speed rotations; does running the engine on a lower speed solve that or will the discs warp anyway after time ? what is the difference in efficiency between the tesla turbine running at high speed and running it at a lower speed ( as fast as possible but low enough to not warp de discs) and: i...

View full post »