Frequency Doublers was "rant city"

[Don Tillman]

   Date: Sun, 21 May 2000 14:00:44 -0400
   From: Harry Bissell <harrybissell at prodigy.net>

   If you have a sine wave
[...]
   If you have a sawtooth wave
[...]
   If you have real stable amplitude and a triangle
[...]


And if you have a square wave, do this (ascii graphics ahead):

        +---> lossy integrator --> comparator -->
input --+                                        XOR gate --> 2x out
        +--------------------------------------->


The lossy integrator parameters are chosen so that the comparator
output is close to 90-degrees from the original signal over the
frequency range of interest.  It could be a simple RC network.  XORing
two square waves 90-degrees apart gives you a 2x square wave.

  -- Don

-- 
Don Tillman
Palo Alto, California, USA
don at till.com
http://www.till.com