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.

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.

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

For a 50 ohm driver for your outputs: come off the 74HC390 divide 5/2 output and buffer the signal with a 74ACTQ240. Then add a 39 ohm series resistor followed by (2) 1N4148 diodes (one to ground the other to +5V), to limit the output, and you have a 50 ohm driver for your outputs. Tom Tom Duckworth tomduck@comcast.net ----- Original Message ----- From: "Bruce Griffiths" <bruce.griffiths@xtra.co.nz> To: "Discussion of precise time and frequency measurement" <time-nuts@febo.com> Sent: Tuesday, July 28, 2009 2:43 PM Subject: Re: [time-nuts] An easy to generate 5, 1 MHz from 10 MHz > 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 -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. >