[time-nuts] Latest measurements on my FTS 4050/S24

Hal Murray hmurray at suespammers.org
Sat Aug 19 19:24:19 EDT 2006


> A handy passive frequency doubler can be made just using a
> double-balanced  mixer.  Feed 5 MHz into the X and R ports connected
> together and take 10 MHz  out of the L port.  You'll loose a few db
> and the waveform becomes rather  triangular but if your goal is to
> sync the internal oscillator in a counter  to an external standard it
> works just fine.  Mixers are often available on  eBay for a very
> modest price.

Neat.  Thanks.


The digital hack for frequency doubling is an XOR gate with some delay.  Feed 
the signal to one input of the XOR and the delayed signal to the other and 
you get out a pulse at each transition.  The delay turns into the pulse width.

If you are using DIPs, the delay can come from an R/C.  Inside an FPGA you 
can use routing delays, and if part of that routing is a FF, you can be sure 
the delay is long enough so that the pulse meets the min clock width.  (Maybe 
not the min on the data sheet, but the min needed to actually clock a FF.)


-- 
The suespammers.org mail server is located in California.  So are all my
other mailboxes.  Please do not send unsolicited bulk e-mail or unsolicited
commercial e-mail to my suespammers.org address or any of my other addresses.
These are my opinions, not necessarily my employer's.  I hate spam.






More information about the time-nuts mailing list