Re: [time-nuts] Have 10 MHz need 19.2 MHz
I received this all jumbled up in one long line without any sort of formatting, because the sender's mail client does not use standardized structure -- so I don't know who wrote what: A 74HC4046 can reach 19.2 MHz Be very careful about specs like that and be sure to read all the fine print. What can run at that speed? The VCO? The phase comparator (and which one -- the one you want to use?)? Also, note that the PC dead zone gets to be a larger and larger percentage of a cycle as the frequency increases, so the control gets less and less precise. The 74HCT9046 may be a better choice (no dead zone), but you may need to select parts to run them at 19+ MHz. No worries, there are hundreds of fast PLLs out there, but most are more complicated to apply than the 4046/9046. Well some parts whose use is so pervasive, for example, the 2N3904 and 2N3906 transistor, they will be around *forever* and reasonably priced. I believe the MC or LM 1496 falls in this category. Ten years ago I thought the same about the 2N, 2N2907, 2N5179, 2N5109, 2N5320 and 5322, and on, and on, and on, and on But they are all long gone as primary parts. So will be the 1496 before long. Of course, as long as 2N3904s are available, you can always build your own 1496 if you're willing to do a bit of selection. BTW, I see that at least some versions of the ON 1496 are already EOL. Best regards, Charles ___ 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.
[time-nuts] Have 10 MHz need 19.2 MHz
List, My reply to Javier Herrerojherr...@hvsistemas.es P Double the 10 MHz to 20 MHz. P With another circuit of 74HC390’s divide 10 MHz to 200 KHz. Then double it twice to 800 KHz with LM 1496 DBM’s. Apply the two frequencies to a LM 1496 DBM and use a LPF to get the 19.2 MHz. P Hardware complicated? A bit. J Only a bit? Only the filter to reject the products that you will have spread in all places, spaced 200 kHz, P I’m not so sure of that at all. The DBM doubler has a difference frequency of zero. And I don’t understand where did you get 200 KHz spaces? J and mainly to remove the 20.8 MHz spurious that you will have as a result of the last mixing, makes this approach difficult. P You are correct that the sum frequency is 20.8 MHz. However the difference frequency being 19.2 MHz makes a 1.6 MHz difference which will allow one to use a simple parallel L-C circuit to get the frequency of choice rather simply. A parallel resonance filter (ignoring stray capacitance for the moment) using a .1uH inductor and a 687pF capacitor resonates at 19.20175 MHz. J I would favour a PLL, and since for the application, short-term stability seems irrelevant, even using a conventional VCO and not a crystal would be enough. A 74HC4046 can reach 19.2 MHz, and you only need a couple of dividers to get a 200 kHz reference to feed it. P That may be another way to do it. I didn’t say my way was thee only way. I said it might be a way. And until one built my circuit idea criticizing that it won’t work well is hypothetical and somewhat arrogant. Building it is the real proof. Never forget about the duck-billed platypus, the animal that couldn’t be, according to *scientific laws*. P According to the data sheets I have for a 74HC4046 to use it at 19.2 MHz you have to be brand specific. Some are only rated to 14 MHz P I thought that the 10 MHz source was a rubidium. That may have been incorrect. If the short term stability is irrelevant as you have stated then other possibilities are also feasible. P But if one uses a 74HC4046 with a VCO (which would be fine with me) one still has to get two matching frequencies. J I figured out the 200 KHz division. P How would you get 200 KHz from the 19.2 MHz for the PLL and where does this come from and how does it fit into your circuit. P Can you use matching harmonics in a PLL? I don’t know. I’m a hobbyist and have to go with what I know or can get from others. J However one doesn’t have to search for a microprocessor that you program and may not be available in a couple of years. The IC’s are cheap and have been and will be around forever. J The LM1496 was discontinued long ago it was a second source of the MC1496 (that is in production). P OK. But a rose is still a rose. Mouser currently has stock of over 4,000 MC1496 for immediate delivery. They are interchangeable. So what is your point? The specified type of DBM is currently available. Sir, methinks, respectfully, that thy are quibbling over nothing, J But never think it will be around forever (yes, as a hobbyist, surely you can find a single piece forever, more if price does not matter too much). P Well some parts whose use is so pervasive, for example, the 2N3904 and 2N3906 transistor, they will be around *forever* and reasonably priced. I believe the MC or LM 1496 falls in this category. Everyone had and still uses them. Although there are a few other IC DBM’s they really are insignificant and very hard to find. J Also, I'm not a bit fan of PICs, quite the contrary, but for example the PIC16F84 has been available from more that 16yr and it is in production... so following your LM1496 criteria, will be available forever :) P OK, but you still have to be able to program any PIC one chooses. Most prevalent posters to the list are programmers or have been trained in programming or like it enough to learn it and do it. Fine. Go for it. Their skill is indispensible in this world. Now comes the BUT part. IMNSHO, I believe that their (programmers) judgment is quite slanted to using microprocessors as a solution to all electrical problems. This leads to over-complicated solutions to many problems. This is actually poor engineering practice. Good engineering is finding the least expensive, reliable, simplest and reproducible method to solve a given problem. Many of us have no skill to use microprocessors. So we find a work-a-round. Microprocessors are fine. Microprocessor use gives us a great quality of life. Modern life as developed nations have would not exist without them. We couldn’t be spied upon without them! P IMHO sometimes an older *brute force* circuit proves that more can be less in implementing what you desire to accomplish. J Brute force is usually brute :) P Perhaps. But if a circuit works reliably, fulfills its objective, and is easily reproduced by others that can easily outweigh
[time-nuts] Have 10 MHz need 19.2 MHz
List, Another hardware possibility. Double the 10 MHz to 20 MHz. With another circuit of 74HC390’s divide 10 MHz to 200 KHz. Then double it twice to 800 KHz with LM 1496 DBM’s. Apply the two frequencies to a LM 1496 DBM and use a LPF to get the 19.2 MHz. Hardware complicated? A bit. However one doesn’t have to search for a microprocessor that you program and may not be available in a couple of years. The IC’s are cheap and have been and will be around forever. IMHO sometimes an older *brute force* circuit proves that more can be less in implementing what you desire to accomplish. Regards, Perrier ___ 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.
Re: [time-nuts] Have 10 MHz need 19.2 MHz
I'm glad I asked this question. I was hoping to get ideas I'd never think of. It's going to be hard to beat that TI PLL chip especially because TI offers free samples. The injection idea seems almost like cheating. I might use part of the idea below to divide down 10MHz then inject that into the 19.2 crystal and let the crystal itself do the rest. On Fri, Jun 7, 2013 at 10:23 AM, Perry Sandeen sandee...@yahoo.com wrote: List, Another hardware possibility. Double the 10 MHz to 20 MHz. With another circuit of 74HC390’s divide 10 MHz to 200 KHz. Then double it twice to 800 KHz with LM 1496 DBM’s. Apply the two frequencies to a LM 1496 DBM and use a LPF to get the 19.2 MHz. Hardware complicated? A bit. However one doesn’t have to search for a microprocessor that you program and may not be available in a couple of years. The IC’s are cheap and have been and will be around forever. IMHO sometimes an older *brute force* circuit proves that more can be less in implementing what you desire to accomplish. Regards, Perrier ___ 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. -- Chris Albertson Redondo Beach, California ___ 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.
Re: [time-nuts] Have 10 MHz need 19.2 MHz
Since the actual crystal frequency appears to be 19.2 MHz rather than 19.5, my original suggestion of injection locking it would have to be modified. For example, you could divide the 10 MHz by 25 ( a single 74HC390 could do it) to make 400 kHz, so 19.2 MHz could sync to the 48th harmonic. Ed ___ 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.
Re: [time-nuts] Have 10 MHz need 19.2 MHz
On 07.06.2013 19:23, Perry Sandeen wrote: List, Another hardware possibility. Double the 10 MHz to 20 MHz. With another circuit of 74HC390’s divide 10 MHz to 200 KHz. Then double it twice to 800 KHz with LM 1496 DBM’s. Apply the two frequencies to a LM 1496 DBM and use a LPF to get the 19.2 MHz. Hardware complicated? A bit. Only a bit? Only the filter to rejetct the products that you will have spreaded in all places, spaced 200kHz, and mainly to remove the 20.8 MHz spurious that you will have as a result of the last mixing, makes this approach difficult. I would favour a PLL, and since for the application, short-term stability seems unrelevant, even using a conventional VCO and not a crystal would be enough. A 74HC4046 can reach 19.2MHz, and you only need a couple of dividers to get a 200kHz reference to feed it. However one doesn’t have to search for a microprocessor that you program and may not be available in a couple of years. The IC’s are cheap and have been and will be around forever. The LM1496 was discontinued long ago it was a second source of the MC1496 (that is in production). But never think it will be around forever (yes, as a hobbyist, surely you can find a single piece forever, more if price does not matter too much). Also, I'm not a bit fan of PICs, quite the contrary, but for example the PIC16F84 has been available from more that 16yr and it is on production... so following your LM1496 criteria, will be available forever :) IMHO sometimes an older *brute force* circuit proves that more can be less in implementing what you desire to accomplish. Brute force is usually brute :) Regards, Javier Regards, Perrier ___ 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. ___ 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.
