Homebrew PCBs

--- In Homebrew_PCBs@yahoogroups.com, "Dave Mucha" <dave_mucha@y...> 
wrote:

> I'd go for the spark gaps.  there are pleanty of individual posts 
> lableled TP3 and such.
> but it seems a strike would wipe out the whole board, even with 
some 
> drain.

It isn't to save the board, it is to reduce the chance for fire. And 
lightning may hit many miles away, you could be looking at the sun 
outside and bam! Your fax machine bites the dust from a lightning hit 
far away. Those points mean the majority of the energy dumps there 
rather than in the components.

The physics of an arc are such that once it forms, relatively little 
voltage is dropped across the arc. Relatively little may still mean a 
hundred volts.

Just like fuses in an amplifier are not there to save the amp, they 
are there to prevent the amp from catching fire. I'm not talking 
about the speaker fuses.

Steve Greenfield