[sdiy] CA3028

[David Cornutt]

Poking around on the Web, I found a frequency tripler circuit
that uses the CA3028 diff amp.  Looked like something that might
be fun to play with, so I got to checking on it.  That's when I found
out that these things are going for about $9 apiece.  Does anyone
know of a substitute that might be less expensive?  Also, has anyone
built this circuit?  I searched the archive and didn't find anything.