> Le 8 juin 2016 à 15:55, Nick Sayer via time-nuts <time-nuts@febo.com> a écrit > : > > I’m contemplating trying my GPS board with an FE-405B. That’s a different > kettle of fish, but at the end of that, if I’m successful, one of the goals > would be to be able to use it for the external reference of my 53220A. > Unfortunately, 15 MHz isn’t one of the options - only 1, 5 and 10.
I saw the same, which put me off trying to do the same. However I am not sure that your approach will work as the specs for the external clock indicate: - EXTernal selects an external reference signal applied to the rear panel Ext Ref In connector. The signal must be: • 1 MHz , 5 MHz, or 10 MHz • 100 mVrms to 2.5 Vrms • sine wave Your output is digital, no? It may function but I wouldn’t trust it. It is a no brainer to get a sine from a square wave, BUT , I seriously doubt that the excellent ADEV can be maintained with all that flipping and flopping going on. I even doubt that it could be kept in a pure sine implementation. Mike > > So I did some googling and found a divide-by-3 circuit using flip-flops, and > then designed a board for it: > > https://oshpark.com/shared_projects/jxXp7wYM > > The circuit uses 3 D flip-flops and 3 NOR gates and has a 50% duty cycle > output that’s 1/3 the frequency of the input. The OSHPark project has a > pointer to the original blog post that has a schematic. The only difference > between their schematic and mine is that in theirs, the third flip-flop has > an inverted clock input. The third NOR gate inverts the clock to achieve that > in mine (also one flip-flop and one NOR gate are unused and have the inputs > tied high). > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. "The power of accurate observation is commonly called cynicism by those who have not got it. » George Bernard Shaw _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
