[sdiy] varactor/varicaps?

[David G. Dixon]

> anybody know much about varicaps? they sound too good to be true...voltage
> variable capacitance up to 200pf?

Well, the value is right, because I use 205pF silvered mica caps in all of
my own filter designs.

However, the big problem I can see right off the bat is that this would give
linear control of filter cutoff, when what you really want is exponential
control.  It might be an interesting way to introduce linear FM to a filter,
but probably not worth it.