Rex wrote: > > John Green wrote: > >> A cheap and easy way is to use a 74HC14, 74HC390. Capacitively couple >> the 10 >> MHz into one of the 6 inputs of the HC14 to square it up, out of that >> into >> one of the divide by 2 inputs of the HC390, that goes to another >> input of >> the HC14 to act as a buffer which provides the 5 MHz output. Next, >> into the >> divide by 5 input of the HC390 to give 1 MHz out. This also goes >> through one >> section of the HC14. There is another section of the HC390 if you >> wish to >> divide down farther. I made one of these to feed an old Marconi service >> monitor that requires 1 MHz instead of 10 MHz as an external reference >> input. I also have 5 MHz and 100KHz available if I need them. True, >> the HC14 >> isn't a proper buffer meant to drive low impedance loads, but it >> seems to >> work OK for me. I laid it out in Eagle and routed out a board with the >> T-Tech here at work but there is no reason you couldn't do it with >> wire on >> perf board. >> _______________________________________________ >> >> > > If you need a stronger output driver, you could look at what was done > in the TAPR TADD-2: > http://www.tapr.org/kits_tadd-2.html > > Schematics are available in the documentation. > > My first htought was that the TADD-2 might work with a modified > version of the PIC code to give lower division outputs (5 or 1 MHz). > It might work for generating the 1 MHz, but I think you would still > need hardware for the 10 MHZ to 5 MHz division. For your task, it may > be easier to do it all in hardware as mentioned above. > Don't copy this circuit slavishly.
Using a single AC04 to buffer 2 different output frequencies is a bad idea as ground bounce within the AC04 package creates significant crosstalk between the 2 outputs. As long as each AC04 is dedicated to a single output frequency (and preferably load) the crosstalk between outputs will be small. Bruce _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
