Re: [time-nuts] wwvb 60 khz tuning fork crystals Some insights
Hal Murray said: They make 74xU04 for many values of x. The U is for Unbuffered. They have lower gain in the linear region. I thought they were intended to be used for things like this, but I don't understand that area. Can anybody give me a quick lesson or point me at a good URL? I always thought the unbuffered U versions were preferred for ring oscillators mostly to save power - you don't want the high-drive output stages to be cooking away in linear mode if not needed. The propagation delay can also be less since the U ones have only one stage instead of three (the building block is the totem-pole inverter stage), but they can't drive very much load anyway. I think that most MSI and LSI parts that have built-in ring/crystal oscillator sections use the U topology, but I don't think there's anything special about it - it's the simplest thing that works. I've made quite a few CD4000 and 74HC oscillators, and never worried too much about U versions or not, except for battery-run items where power is critical (or you can run the oscillator at lower voltage). Often they are made from inverting gates that are part of a shared package, where you wouldn't want puny drive capability in the other gates anyway. They are relative power hogs though, whenever linear biasing is needed. Except in the 4000 series, I don't know if U versions are available in anything but the '04 hex inverter, but I suppose it's possible. I think the Schmitt-trigger types like HC14 are necessarily buffered, so have three stages, since you need a non-inverted version of the signal for the positive feedback to the input. I've never tried making one in 74AC - I don't know if it's even possible to bias one up that way without it burning up. I'm working on some related circuits now, so maybe I'll set up an experiment to see how much current it would take for one inverter - I've often wondered about this. I read about this years ago in various CMOS application notes, so I may be missing some key points - there should be plenty of info online. The older generation (when CMOS was fairly new) info may provide more detail about the guts than that related to the newer, higher performance families. 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] wwvb 60 khz tuning fork crystals Some insights
I suspect the threads been hijacked into a why doesn't email work. I would say lets kill this thread. Regards Paul WB8TSL On Thu, Jun 27, 2013 at 5:35 PM, ed breya e...@telight.com wrote: Hal Murray said: They make 74xU04 for many values of x. The U is for Unbuffered. They have lower gain in the linear region. I thought they were intended to be used for things like this, but I don't understand that area. Can anybody give me a quick lesson or point me at a good URL? I always thought the unbuffered U versions were preferred for ring oscillators mostly to save power - you don't want the high-drive output stages to be cooking away in linear mode if not needed. The propagation delay can also be less since the U ones have only one stage instead of three (the building block is the totem-pole inverter stage), but they can't drive very much load anyway. I think that most MSI and LSI parts that have built-in ring/crystal oscillator sections use the U topology, but I don't think there's anything special about it - it's the simplest thing that works. I've made quite a few CD4000 and 74HC oscillators, and never worried too much about U versions or not, except for battery-run items where power is critical (or you can run the oscillator at lower voltage). Often they are made from inverting gates that are part of a shared package, where you wouldn't want puny drive capability in the other gates anyway. They are relative power hogs though, whenever linear biasing is needed. Except in the 4000 series, I don't know if U versions are available in anything but the '04 hex inverter, but I suppose it's possible. I think the Schmitt-trigger types like HC14 are necessarily buffered, so have three stages, since you need a non-inverted version of the signal for the positive feedback to the input. I've never tried making one in 74AC - I don't know if it's even possible to bias one up that way without it burning up. I'm working on some related circuits now, so maybe I'll set up an experiment to see how much current it would take for one inverter - I've often wondered about this. I read about this years ago in various CMOS application notes, so I may be missing some key points - there should be plenty of info online. The older generation (when CMOS was fairly new) info may provide more detail about the guts than that related to the newer, higher performance families. Ed __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://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.
Re: [time-nuts] wwvb 60 khz tuning fork crystals Some insights
I presume you used the regular 74HC04 or 74HCU04 inverter, not the 74HC14 Schmitt trigger input type?? If the '14 is actually used, that may explain the problems around setting the feedback biasing resistor value - you may be overriding the built-in hysteresis to get it in the linear region. Usually that R isn't very critical with regular crystals, but maybe tuning fork types need more gain, or, if it's actually a '14, the input impedance is probably lower than a regular gate, so it's loading the resonator. 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] wwvb 60 khz tuning fork crystals Some insights
Ed strange no body and you sent it 3 days ago. On Thu, Jun 27, 2013 at 12:13 AM, ed breya e...@telight.com wrote: I presume you used the regular 74HC04 or 74HCU04 inverter, not the 74HC14 Schmitt trigger input type?? If the '14 is actually used, that may explain the problems around setting the feedback biasing resistor value - you may be overriding the built-in hysteresis to get it in the linear region. Usually that R isn't very critical with regular crystals, but maybe tuning fork types need more gain, or, if it's actually a '14, the input impedance is probably lower than a regular gate, so it's loading the resonator. Ed __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://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.
Re: [time-nuts] wwvb 60 khz tuning fork crystals Some insights
If you're talking about the email processing, I think something's going on. It sometimes take two or even three tries to get one through, while the most recent one I just sent (about regulators) went OK the first time. Let's see if this one does. B BTW how do you guys get the thread to continue on from the current message? I have only been able to copy and paste parts into the new email, and that loses some of the links and formatting in some way. I don't think this is the cause of the email problem above, since it seems uncorrelated with any editing or whether I send a brand new topic. I'm using an old version of Eudora (7.1.0.9), if that matters. Ed Ed strange no body and you sent it 3 days ago. On Thu, Jun 27, 2013 at 12:13 AM, ed breya https://www.febo.com/cgi-bin/mailman/listinfo/time-nutseb at telight.com wrote: I presume you used the regular 74HC04 or 74HCU04 inverter, not the 74HC14 Schmitt trigger input type?? If the '14 is actually used, that may explain the problems around setting the feedback biasing resistor value - you may be overriding the built-in hysteresis to get it in the linear region. Usually that R isn't very critical with regular crystals, but maybe tuning fork types need more gain, or, if it's actually a '14, the input impedance is probably lower than a regular gate, so it's loading the resonator. 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] wwvb 60 khz tuning fork crystals Some insights
It's probably a software bug in the NSA monitoring system that keeps dropping some of the message content. :) - Original Message - From: ed breya e...@telight.com To: time-nuts@febo.com Sent: Sunday, June 30, 2013 3:05 PM Subject: Re: [time-nuts] wwvb 60 khz tuning fork crystals Some insights If you're talking about the email processing, I think something's going on. It sometimes take two or even three tries to get one through, while the most recent one I just sent (about regulators) went OK the first time. Let's see if this one does. B BTW how do you guys get the thread to continue on from the current message? I have only been able to copy and paste parts into the new email, and that loses some of the links and formatting in some way. I don't think this is the cause of the email problem above, since it seems uncorrelated with any editing or whether I send a brand new topic. I'm using an old version of Eudora (7.1.0.9), if that matters. Ed Ed strange no body and you sent it 3 days ago. On Thu, Jun 27, 2013 at 12:13 AM, ed breya https://www.febo.com/cgi-bin/mailman/listinfo/time-nutseb at telight.com wrote: I presume you used the regular 74HC04 or 74HCU04 inverter, not the 74HC14 Schmitt trigger input type?? If the '14 is actually used, that may explain the problems around setting the feedback biasing resistor value - you may be overriding the built-in hysteresis to get it in the linear region. Usually that R isn't very critical with regular crystals, but maybe tuning fork types need more gain, or, if it's actually a '14, the input impedance is probably lower than a regular gate, so it's loading the resonator. 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. ___ 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] wwvb 60 khz tuning fork crystals Some insights
Especially as the inverting gates have independent source and/or drain connections - series resistors can be used to lower even more the consumption when biased in the linear region... On 6/28/2013 7:20 AM, Don Latham wrote: Maybe the old 4007 cmos would be better... Don paul swed Yes it makes a very fine 35 Mhz oscillator and reasonably stable. Been there and done that. Hey the systems done. May remod it one day but bigger fish to fry with the d-psk-r Regards Paul WB8TSL On Thu, Jun 27, 2013 at 6:41 PM, David McGaw n1...@alum.dartmouth.orgwrote: Lower gain is better as long as it oscillates. The 74HCU04 is unlikely to drive spurious responses. The 74HC04 is OK as long as you keep the feedback gain low - sometimes a series resistor from the output to the resonant circuit is required. A 74HC14 is the WRONG part for the job as it can and will oscillate without the crystal controlling it - just try it with a resistor for feedback and a capacitor to ground at the input, no crystal. David N1HAC On 6/27/13 6:30 PM, paul swed wrote: I will say the fact is the 74hc14 is a bit of a power pig we are talking 12 ma. The rcvr is something much less like 100 ua. At least for the moment it all works but 12 ma is a pig. Especially when you take the signal out and knock it down to 100-200 uv. Regards Paul. On Thu, Jun 27, 2013 at 5:37 PM, ed breyae...@telight.com wrote: Still having email problems - here we go again. This is second try, please excuse if both show up. Hal Murray said: They make 74xU04 for many values of x. The U is for Unbuffered. They have lower gain in the linear region. I thought they were intended to be used for things like this, but I don't understand that area. Can anybody give me a quick lesson or point me at a good URL? I always thought the unbuffered U versions were preferred for ring oscillators mostly to save power - you don't want the high-drive output stages to be cooking away in linear mode if not needed. The propagation delay can also be less since the U ones have only one stage instead of three (the building block is the totem-pole inverter stage), but they can't drive very much load anyway. I think that most MSI and LSI parts that have built-in ring/crystal oscillator sections use the U topology, but I don't think there's anything special about it - it's the simplest thing that works. I've made quite a few CD4000 and 74HC oscillators, and never worried too much about U versions or not, except for battery-run items where power is critical (or you can run the oscillator at lower voltage). Often they are made from inverting gates that are part of a shared package, where you wouldn't want puny drive capability in the other gates anyway. They are relative power hogs though, whenever linear biasing is needed. Except in the 4000 series, I don't know if U versions are available in anything but the '04 hex inverter, but I suppose it's possible. I think the Schmitt-trigger types like HC14 are necessarily buffered, so have three stages, since you need a non-inverted version of the signal for the positive feedback to the input. I've never tried making one in 74AC - I don't know if it's even possible to bias one up that way without it burning up. I'm working on some related circuits now, so maybe I'll set up an experiment to see how much current it would take for one inverter - I've often wondered about this. I read about this years ago in various CMOS application notes, so I may be missing some key points - there should be plenty of info online. The older generation (when CMOS was fairly new) info may provide more detail about the guts than that related to the newer, higher performance families. Ed ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshtt**ps://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://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-nutshttps://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-nutshttps://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. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to
Re: [time-nuts] wwvb 60 khz tuning fork crystals Some insights
To answer the several questions. It is a 74hc14. Burt the feedback resistor is 22M The xtal drive resistor is below 270K. So think of it actually as a 22 M in parallel with in my case about 200K. Granted the series drive leg has a 230pf cap to ground next to the xtal and then the xtal in series to pin1. Ed good comment on the 74c04. May tinker with that. Though the HC14s working pretty nicely now. What I find odd is that the traditional 2 caps to ground with one being variable created very very slow startups or unstable startup. Last comment yes indeed those crystals are small. Regards Paul WB8TSL On Thu, Jun 27, 2013 at 12:17 AM, ed breya e...@telight.com wrote: Email still seems to not be getting through - it seems like sending twice works sometimes. Here this one goes again - sorry if it shows up twice: I presume you used the regular 74HC04 or 74HCU04 inverter, not the 74HC14 Schmitt trigger input type?? If the '14 is actually used, that may explain the problems around setting the feedback biasing resistor value - you may be overriding the built-in hysteresis to get it in the linear region. Usually that R isn't very critical with regular crystals, but maybe tuning fork types need more gain, or, if it's actually a '14, the input impedance is probably lower than a regular gate, so it's loading the resonator. Ed __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://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.
Re: [time-nuts] wwvb 60 khz tuning fork crystals Some insights
paulsw...@gmail.com said: Ed good comment on the 74c04. May tinker with that. Though the HC14s working pretty nicely now. They make 74xU04 for many values of x. The U is for Unbuffered. They have lower gain in the linear region. I thought they were intended to be used for things like this, but I don't understand that area. Can anybody give me a quick lesson or point me at a good URL? -- These are my opinions. I hate spam. ___ 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] wwvb 60 khz tuning fork crystals Some insights
Hal I seem to have only a bit of a clue here because I thought I would just grab any circuit off the internet and away I would go. Did not quite turn out that way. Regards Paul WB8TSL On Thu, Jun 27, 2013 at 3:09 PM, Hal Murray hmur...@megapathdsl.net wrote: paulsw...@gmail.com said: Ed good comment on the 74c04. May tinker with that. Though the HC14s working pretty nicely now. They make 74xU04 for many values of x. The U is for Unbuffered. They have lower gain in the linear region. I thought they were intended to be used for things like this, but I don't understand that area. Can anybody give me a quick lesson or point me at a good URL? -- These are my opinions. I hate spam. ___ 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.
Re: [time-nuts] wwvb 60 khz tuning fork crystals Some insights
Still having email problems - here we go again. This is second try, please excuse if both show up. Hal Murray said: They make 74xU04 for many values of x. The U is for Unbuffered. They have lower gain in the linear region. I thought they were intended to be used for things like this, but I don't understand that area. Can anybody give me a quick lesson or point me at a good URL? I always thought the unbuffered U versions were preferred for ring oscillators mostly to save power - you don't want the high-drive output stages to be cooking away in linear mode if not needed. The propagation delay can also be less since the U ones have only one stage instead of three (the building block is the totem-pole inverter stage), but they can't drive very much load anyway. I think that most MSI and LSI parts that have built-in ring/crystal oscillator sections use the U topology, but I don't think there's anything special about it - it's the simplest thing that works. I've made quite a few CD4000 and 74HC oscillators, and never worried too much about U versions or not, except for battery-run items where power is critical (or you can run the oscillator at lower voltage). Often they are made from inverting gates that are part of a shared package, where you wouldn't want puny drive capability in the other gates anyway. They are relative power hogs though, whenever linear biasing is needed. Except in the 4000 series, I don't know if U versions are available in anything but the '04 hex inverter, but I suppose it's possible. I think the Schmitt-trigger types like HC14 are necessarily buffered, so have three stages, since you need a non-inverted version of the signal for the positive feedback to the input. I've never tried making one in 74AC - I don't know if it's even possible to bias one up that way without it burning up. I'm working on some related circuits now, so maybe I'll set up an experiment to see how much current it would take for one inverter - I've often wondered about this. I read about this years ago in various CMOS application notes, so I may be missing some key points - there should be plenty of info online. The older generation (when CMOS was fairly new) info may provide more detail about the guts than that related to the newer, higher performance families. 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] wwvb 60 khz tuning fork crystals Some insights
I will say the fact is the 74hc14 is a bit of a power pig we are talking 12 ma. The rcvr is something much less like 100 ua. At least for the moment it all works but 12 ma is a pig. Especially when you take the signal out and knock it down to 100-200 uv. Regards Paul. On Thu, Jun 27, 2013 at 5:37 PM, ed breya e...@telight.com wrote: Still having email problems - here we go again. This is second try, please excuse if both show up. Hal Murray said: They make 74xU04 for many values of x. The U is for Unbuffered. They have lower gain in the linear region. I thought they were intended to be used for things like this, but I don't understand that area. Can anybody give me a quick lesson or point me at a good URL? I always thought the unbuffered U versions were preferred for ring oscillators mostly to save power - you don't want the high-drive output stages to be cooking away in linear mode if not needed. The propagation delay can also be less since the U ones have only one stage instead of three (the building block is the totem-pole inverter stage), but they can't drive very much load anyway. I think that most MSI and LSI parts that have built-in ring/crystal oscillator sections use the U topology, but I don't think there's anything special about it - it's the simplest thing that works. I've made quite a few CD4000 and 74HC oscillators, and never worried too much about U versions or not, except for battery-run items where power is critical (or you can run the oscillator at lower voltage). Often they are made from inverting gates that are part of a shared package, where you wouldn't want puny drive capability in the other gates anyway. They are relative power hogs though, whenever linear biasing is needed. Except in the 4000 series, I don't know if U versions are available in anything but the '04 hex inverter, but I suppose it's possible. I think the Schmitt-trigger types like HC14 are necessarily buffered, so have three stages, since you need a non-inverted version of the signal for the positive feedback to the input. I've never tried making one in 74AC - I don't know if it's even possible to bias one up that way without it burning up. I'm working on some related circuits now, so maybe I'll set up an experiment to see how much current it would take for one inverter - I've often wondered about this. I read about this years ago in various CMOS application notes, so I may be missing some key points - there should be plenty of info online. The older generation (when CMOS was fairly new) info may provide more detail about the guts than that related to the newer, higher performance families. Ed __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://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.
Re: [time-nuts] wwvb 60 khz tuning fork crystals Some insights
Lower gain is better as long as it oscillates. The 74HCU04 is unlikely to drive spurious responses. The 74HC04 is OK as long as you keep the feedback gain low - sometimes a series resistor from the output to the resonant circuit is required. A 74HC14 is the WRONG part for the job as it can and will oscillate without the crystal controlling it - just try it with a resistor for feedback and a capacitor to ground at the input, no crystal. David N1HAC On 6/27/13 6:30 PM, paul swed wrote: I will say the fact is the 74hc14 is a bit of a power pig we are talking 12 ma. The rcvr is something much less like 100 ua. At least for the moment it all works but 12 ma is a pig. Especially when you take the signal out and knock it down to 100-200 uv. Regards Paul. On Thu, Jun 27, 2013 at 5:37 PM, ed breya e...@telight.com wrote: Still having email problems - here we go again. This is second try, please excuse if both show up. Hal Murray said: They make 74xU04 for many values of x. The U is for Unbuffered. They have lower gain in the linear region. I thought they were intended to be used for things like this, but I don't understand that area. Can anybody give me a quick lesson or point me at a good URL? I always thought the unbuffered U versions were preferred for ring oscillators mostly to save power - you don't want the high-drive output stages to be cooking away in linear mode if not needed. The propagation delay can also be less since the U ones have only one stage instead of three (the building block is the totem-pole inverter stage), but they can't drive very much load anyway. I think that most MSI and LSI parts that have built-in ring/crystal oscillator sections use the U topology, but I don't think there's anything special about it - it's the simplest thing that works. I've made quite a few CD4000 and 74HC oscillators, and never worried too much about U versions or not, except for battery-run items where power is critical (or you can run the oscillator at lower voltage). Often they are made from inverting gates that are part of a shared package, where you wouldn't want puny drive capability in the other gates anyway. They are relative power hogs though, whenever linear biasing is needed. Except in the 4000 series, I don't know if U versions are available in anything but the '04 hex inverter, but I suppose it's possible. I think the Schmitt-trigger types like HC14 are necessarily buffered, so have three stages, since you need a non-inverted version of the signal for the positive feedback to the input. I've never tried making one in 74AC - I don't know if it's even possible to bias one up that way without it burning up. I'm working on some related circuits now, so maybe I'll set up an experiment to see how much current it would take for one inverter - I've often wondered about this. I read about this years ago in various CMOS application notes, so I may be missing some key points - there should be plenty of info online. The older generation (when CMOS was fairly new) info may provide more detail about the guts than that related to the newer, higher performance families. Ed __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://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. ___ 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] wwvb 60 khz tuning fork crystals Some insights
Yes it makes a very fine 35 Mhz oscillator and reasonably stable. Been there and done that. Hey the systems done. May remod it one day but bigger fish to fry with the d-psk-r Regards Paul WB8TSL On Thu, Jun 27, 2013 at 6:41 PM, David McGaw n1...@alum.dartmouth.orgwrote: Lower gain is better as long as it oscillates. The 74HCU04 is unlikely to drive spurious responses. The 74HC04 is OK as long as you keep the feedback gain low - sometimes a series resistor from the output to the resonant circuit is required. A 74HC14 is the WRONG part for the job as it can and will oscillate without the crystal controlling it - just try it with a resistor for feedback and a capacitor to ground at the input, no crystal. David N1HAC On 6/27/13 6:30 PM, paul swed wrote: I will say the fact is the 74hc14 is a bit of a power pig we are talking 12 ma. The rcvr is something much less like 100 ua. At least for the moment it all works but 12 ma is a pig. Especially when you take the signal out and knock it down to 100-200 uv. Regards Paul. On Thu, Jun 27, 2013 at 5:37 PM, ed breya e...@telight.com wrote: Still having email problems - here we go again. This is second try, please excuse if both show up. Hal Murray said: They make 74xU04 for many values of x. The U is for Unbuffered. They have lower gain in the linear region. I thought they were intended to be used for things like this, but I don't understand that area. Can anybody give me a quick lesson or point me at a good URL? I always thought the unbuffered U versions were preferred for ring oscillators mostly to save power - you don't want the high-drive output stages to be cooking away in linear mode if not needed. The propagation delay can also be less since the U ones have only one stage instead of three (the building block is the totem-pole inverter stage), but they can't drive very much load anyway. I think that most MSI and LSI parts that have built-in ring/crystal oscillator sections use the U topology, but I don't think there's anything special about it - it's the simplest thing that works. I've made quite a few CD4000 and 74HC oscillators, and never worried too much about U versions or not, except for battery-run items where power is critical (or you can run the oscillator at lower voltage). Often they are made from inverting gates that are part of a shared package, where you wouldn't want puny drive capability in the other gates anyway. They are relative power hogs though, whenever linear biasing is needed. Except in the 4000 series, I don't know if U versions are available in anything but the '04 hex inverter, but I suppose it's possible. I think the Schmitt-trigger types like HC14 are necessarily buffered, so have three stages, since you need a non-inverted version of the signal for the positive feedback to the input. I've never tried making one in 74AC - I don't know if it's even possible to bias one up that way without it burning up. I'm working on some related circuits now, so maybe I'll set up an experiment to see how much current it would take for one inverter - I've often wondered about this. I read about this years ago in various CMOS application notes, so I may be missing some key points - there should be plenty of info online. The older generation (when CMOS was fairly new) info may provide more detail about the guts than that related to the newer, higher performance families. Ed ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshtt**ps://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://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-nutshttps://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-nutshttps://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.
Re: [time-nuts] wwvb 60 khz tuning fork crystals Some insights
Hi The U / unbuffered inverter has less delay than it's buffered cousin. In order to get an oscillator, you need to satisfy Barkhausen's criteria: loop gain 1 to start up loop gain = 1 in operation net phase around the loop = 0 (modulo 360 degrees) As long as the gate has more gain than the crystal network (crystal plus caps) has loss, it will start. As long as the delay through the gate isn't to crazy, it will oscillate with about a 180 degree phase shift on the crystal network, and 180 degrees through the inverter. In order to start, you want to get the inverter in it's linear region. That's not at all easy with a schmitt trigger. Much easier with a normal inverter. Bob On Jun 27, 2013, at 3:09 PM, Hal Murray hmur...@megapathdsl.net wrote: paulsw...@gmail.com said: Ed good comment on the 74c04. May tinker with that. Though the HC14s working pretty nicely now. They make 74xU04 for many values of x. The U is for Unbuffered. They have lower gain in the linear region. I thought they were intended to be used for things like this, but I don't understand that area. Can anybody give me a quick lesson or point me at a good URL? -- These are my opinions. I hate spam. ___ 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.
Re: [time-nuts] wwvb 60 khz tuning fork crystals Some insights
Maybe the old 4007 cmos would be better... Don paul swed Yes it makes a very fine 35 Mhz oscillator and reasonably stable. Been there and done that. Hey the systems done. May remod it one day but bigger fish to fry with the d-psk-r Regards Paul WB8TSL On Thu, Jun 27, 2013 at 6:41 PM, David McGaw n1...@alum.dartmouth.orgwrote: Lower gain is better as long as it oscillates. The 74HCU04 is unlikely to drive spurious responses. The 74HC04 is OK as long as you keep the feedback gain low - sometimes a series resistor from the output to the resonant circuit is required. A 74HC14 is the WRONG part for the job as it can and will oscillate without the crystal controlling it - just try it with a resistor for feedback and a capacitor to ground at the input, no crystal. David N1HAC On 6/27/13 6:30 PM, paul swed wrote: I will say the fact is the 74hc14 is a bit of a power pig we are talking 12 ma. The rcvr is something much less like 100 ua. At least for the moment it all works but 12 ma is a pig. Especially when you take the signal out and knock it down to 100-200 uv. Regards Paul. On Thu, Jun 27, 2013 at 5:37 PM, ed breya e...@telight.com wrote: Still having email problems - here we go again. This is second try, please excuse if both show up. Hal Murray said: They make 74xU04 for many values of x. The U is for Unbuffered. They have lower gain in the linear region. I thought they were intended to be used for things like this, but I don't understand that area. Can anybody give me a quick lesson or point me at a good URL? I always thought the unbuffered U versions were preferred for ring oscillators mostly to save power - you don't want the high-drive output stages to be cooking away in linear mode if not needed. The propagation delay can also be less since the U ones have only one stage instead of three (the building block is the totem-pole inverter stage), but they can't drive very much load anyway. I think that most MSI and LSI parts that have built-in ring/crystal oscillator sections use the U topology, but I don't think there's anything special about it - it's the simplest thing that works. I've made quite a few CD4000 and 74HC oscillators, and never worried too much about U versions or not, except for battery-run items where power is critical (or you can run the oscillator at lower voltage). Often they are made from inverting gates that are part of a shared package, where you wouldn't want puny drive capability in the other gates anyway. They are relative power hogs though, whenever linear biasing is needed. Except in the 4000 series, I don't know if U versions are available in anything but the '04 hex inverter, but I suppose it's possible. I think the Schmitt-trigger types like HC14 are necessarily buffered, so have three stages, since you need a non-inverted version of the signal for the positive feedback to the input. I've never tried making one in 74AC - I don't know if it's even possible to bias one up that way without it burning up. I'm working on some related circuits now, so maybe I'll set up an experiment to see how much current it would take for one inverter - I've often wondered about this. I read about this years ago in various CMOS application notes, so I may be missing some key points - there should be plenty of info online. The older generation (when CMOS was fairly new) info may provide more detail about the guts than that related to the newer, higher performance families. Ed ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshtt**ps://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://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-nutshttps://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-nutshttps://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. -- Neither the voice of authority nor the weight of reason and argument are as significant as experiment, for thence comes quiet to the mind. De Erroribus Medicorum, R. Bacon, 13th century. If you don't know what it is, don't poke it. Ghost in the Shell Dr. Don Latham AJ7LL Six
Re: [time-nuts] wwvb 60 khz tuning fork crystals Some insights
Email still seems to not be getting through - it seems like sending twice works sometimes. Here this one goes again - sorry if it shows up twice: I presume you used the regular 74HC04 or 74HCU04 inverter, not the 74HC14 Schmitt trigger input type?? If the '14 is actually used, that may explain the problems around setting the feedback biasing resistor value - you may be overriding the built-in hysteresis to get it in the linear region. Usually that R isn't very critical with regular crystals, but maybe tuning fork types need more gain, or, if it's actually a '14, the input impedance is probably lower than a regular gate, so it's loading the resonator. 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.
