[sdiy] frequency doubling

[Magnus Danielson]

From: Mountain Man <mtman at cloud9.net>
Subject: [sdiy] frequency doubling
Date: Fri, 25 May 2001 06:48:47 -0400

> Hi folks,

Hi Elby,

> Thanks very much for all the input on my Xpander powersupply; I'll be
> doing some testing over the weekend based on these comments :)
> 
> On a different topic, I'm interested in building a frequency doubling
> circuit.  There was some talk here a while back which I haven't been
> able to find in the archives.  The gist, as I recall, was to create a
> 50% duty cycle square with the same frequency as the original circuit,
> then use leading and falling edges to create trigger pulses.  I
> understand most of this, but there are two parts of the process I'm
> unclear on.  First, how would I create a 50% square wave from a
> non-symetric input (if its symmetric about a known voltage, I know to
> simply use a comparator).  In particular, I have a square wave that's
> not 50% - what do I need to do to it.  The other part is how to convert
> narrow trigger pulses (after doubling) back into something like a square
> wave or triangle.  I know how to get fixed-width pulses (using a 555 for
> example), but that won't work well over a range of frequencies.
> Suggestions?

Well... I've schetched an sawtooth frequency doubler, just to show how
it could possibly be done (it is an El Cheapo solution and can have
many drawbacks, but please just look at it to learn some tricks). It
on my schematic page:
http://home.swipnet.se/cfmd/synths/schematics/

Maybe not what you are looking for, but could be good as an
exercise...

PS. I haven't actually built it, but I see no major trouble in why it
should not work, naturally with flaws, but still kind of work.

Cheers,
Magnus