![]() | This is an archive of past discussions. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page. |
Archive 1 |
I think these could all be merged: Timing crystal, Quartz oscillator, Crystal oscillator. If no one objects, I will put them all under Crystal oscillator. And maybe Quartz clock, also. - Omegatron 20:15, May 4, 2004 (UTC)
I guess
quartz clock and
crystal oscillator should be separate articles. One is a specific application of the other. I will move some material from each to the other, though. -
Omegatron 15:16, May 7, 2004 (UTC)
From the article: For example, steel is very elastic and has a high speed of sound. It was often used in mechanical filters before quartz.
What is a mechanical filter, how was that one used, what has it to do with oscillators? Thanks, -- Abdull 09:32, 19 August 2005 (UTC)
PhysicistQuery 17:24, 20 July 2007 (UTC)The most common mechanical filters were typically cylindrical rods of steel with wide sections and narrow sections along their length. Electroacoustic transducers were used to excite torsional motion, and the wide sections acted as the mass loads and the narrow sections served as the springs. Such filters were analogues of LC filters with all the capacitors grounded.
Is a crystal oscillator made up only by the single crystal and the feedback/amplifier, or does one still need additional components such as inductors and capacitors? -- Abdull 10:14, 19 August 2005 (UTC)
On a similar note, does anyone know what is the exact difference (if any) between a crystal oscillator and a crystal resonator. Are they synonyms, or does one imply additional circuitry or some other difference? Mattopia 09:24, 27 April 2007 (UTC)
If a 1MHz crystal oscillator is put in series with a 3v battery will the voltage in the circuit jump from 3v to 0v at a frequency of 1MHz??? Wolfmankurd 17:25, 28 April 2007 (UTC)
The Pierce oscillator article says that crystals tuned to a particular "parallel resonance frequency" are tuned using a Pierce oscillator circuit.
So ... what about crystals tuned to a particular "series resonance frequency"? What kind of oscillator circuits ( Category:Oscillators ) resonates at the series resonance frequency? And which one(s) in particular is(are) the one(s) used by crystal manufacturers? -- 76.209.28.72 05:43, 13 June 2007 (UTC)
PhysicistQuery 17:50, 20 July 2007 (UTC)If you look at the load presented by the oscillator to the crystal under steady-state conditions, it will consist of a negative resistance in series or in parallel with a reactance. The negative resistance will provide the energy needed to overcome the losses in the crystal; the reactance shifts the resonant frequency.
At the present time, the most common configuration for "simple" oscillators is the Pierce configuration, largely because all its elements can be integrated, and it naturally provides an output that is approximately symmetrical between the rails. This makes it convenient for a simple logic buffer to provide a rail-to-rail output suitable for driving digital systems. The reactance of the Pierce oscillator is naturally capacitive, and this is why the crystal is specified with a capacitive load (a pedantic point, but the circuit configuration of a Pierce circuit essentially provides negative impedance and capacitance in series - the "parallel" here refers only to a historic measurement method for the crystal that used a parallel capacitor). The Pierce oscillator can be modified using an external inductor in series with the crystal so that it is operated at series resonance, but this is seldom desirable except when it is necessary to tune the crystal.
An 'ideal' cross-coupled oscillator would ideally operate at series resonance, but in practice stray capacitances are inverted such that the majority of integrated circuit designs provide an inductive load to the crystal. If these oscillators are allowed to limit, the effective series inductance can become quite large.
"Each new distinct crystal source needs to be rigorously justified, since each one introduces new, difficult to debug probabilistic failure modes, due to multiple crystal interactions, into equipment."
Thats a new one on me. What is the failure mode, in what way do the xtals interact? Tabby ( talk) 23:39, 22 December 2007 (UTC)
Does anyone know what 20MHz crystal oscillators are used for? If so, please add to the table. Thanks. Pi.1415926535 ( talk) 15:05, 20 April 2008 (UTC)
20MHz crystals are used for 10Mbit/s ethernet, which uses a 20MHz clock and Manchester encoding. I've added it to the table. Glenn Anderson ( talk) 00:50, 7 January 2009 (UTC)
why are 33.33 MHz and 40 MHz mentioned but not on the list? what are they for? 09:26, 2 March 2009 (UTC)
The link, as well as the associated title, in reference 4 is the same as that of reference 2. The only difference is that reference 4 provides more title detail. This artificially inflates the number of references. MVD ( talk) 17:03, 23 March 2009 (UTC)
The hyperlink for the article The Evolution of the Quartz Crystal Clock by Warren A. Marrison has gone stale. The corrected link is as follows:
http://www.ieee-uffc.org/main/history.asp?file=marrison
I don't know how to edit the list of references, hopefully some enterprising admin will pick up this torch and run with it. —Preceding unsigned comment added by 72.13.210.165 ( talk) 03:08, 17 April 2009 (UTC)
Used in VCXO for DSL applications. —Preceding unsigned comment added by 24.205.237.171 ( talk) 21:41, 22 October 2009 (UTC)
You can get a quartz crystal ground for any frequency. The Digi Key on-line catalog lists more than 400 frequencies. The listing isn't very useful - there's a number of reasons to pick any particular freqeuncy and there's no general significance in any particular numeric value, let alone a list of hundreds. It's of no encyclopediac value to say the Binford 6100 used a 16.123 MHZ crystal while the sucessor model used a 16.321 MHZ clock unless this detail was actually significant. -- Wtshymanski ( talk) 21:02, 7 December 2009 (UTC)
Agree that the frequency list is not interesting as it stands. A list of "standard application" frequencies that gave a bit of background might be - but should probably be a separate page, and would include frequencies that are not directly related to crystals. BTW, the references to 32 kHz are perhaps less irritating than including the irrelevant precision - but maybe they should merely be described as "watch crystals" except in a single place where 32768Hz is given as a commonly used frequency for these? PhysicistQuery ( talk) 12:19, 22 December 2010 (UTC)
What does it mean: SPXO? Regards -- Elcap ( talk) 17:04, 14 September 2010 (UTC)
AT cut crystal: The description of frequency-temperature shape of the AT cut as "sine" is misleading. Third order would be correct. This seems to be a case where a picture would be worth a thousand words. PhysicistQuery ( talk) 11:56, 22 December 2010 (UTC)
SC cut crystal: The statement "coupled modes are worse than the AT" does not seem to be borne out in practice. Indeed, the performance of the MCXO relies on the excursions due to coupled modes being very small. Would the author perhaps be referring to the requirement to suppress the (usually more active) B-mode vibration at (about) 10% lower frequency than the wanted frequency? This is not at all the same thing as a coupled mode. BTW, coupled modes are not described/defined anywhere in the article, so this reference is anyway meaningless to general readers PhysicistQuery ( talk) 11:56, 22 December 2010 (UTC) Similarly, the temperature sensitivity (third-order coefficient) of the SC is quite similar to the AT. Because of the high inflection temperature, however, the temperature sensitivity of an SC cut crystal can be made relatively small for use in an ovened oscillator. On the other hand, the frequency-temperature sensitivity for temperature ranges that are centred near "normal" temperature is considerably greater for an SC cut than for an AT. PhysicistQuery ( talk) 12:04, 22 December 2010 (UTC)
![]() | This is an archive of past discussions. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page. |
Archive 1 |
I think these could all be merged: Timing crystal, Quartz oscillator, Crystal oscillator. If no one objects, I will put them all under Crystal oscillator. And maybe Quartz clock, also. - Omegatron 20:15, May 4, 2004 (UTC)
I guess
quartz clock and
crystal oscillator should be separate articles. One is a specific application of the other. I will move some material from each to the other, though. -
Omegatron 15:16, May 7, 2004 (UTC)
From the article: For example, steel is very elastic and has a high speed of sound. It was often used in mechanical filters before quartz.
What is a mechanical filter, how was that one used, what has it to do with oscillators? Thanks, -- Abdull 09:32, 19 August 2005 (UTC)
PhysicistQuery 17:24, 20 July 2007 (UTC)The most common mechanical filters were typically cylindrical rods of steel with wide sections and narrow sections along their length. Electroacoustic transducers were used to excite torsional motion, and the wide sections acted as the mass loads and the narrow sections served as the springs. Such filters were analogues of LC filters with all the capacitors grounded.
Is a crystal oscillator made up only by the single crystal and the feedback/amplifier, or does one still need additional components such as inductors and capacitors? -- Abdull 10:14, 19 August 2005 (UTC)
On a similar note, does anyone know what is the exact difference (if any) between a crystal oscillator and a crystal resonator. Are they synonyms, or does one imply additional circuitry or some other difference? Mattopia 09:24, 27 April 2007 (UTC)
If a 1MHz crystal oscillator is put in series with a 3v battery will the voltage in the circuit jump from 3v to 0v at a frequency of 1MHz??? Wolfmankurd 17:25, 28 April 2007 (UTC)
The Pierce oscillator article says that crystals tuned to a particular "parallel resonance frequency" are tuned using a Pierce oscillator circuit.
So ... what about crystals tuned to a particular "series resonance frequency"? What kind of oscillator circuits ( Category:Oscillators ) resonates at the series resonance frequency? And which one(s) in particular is(are) the one(s) used by crystal manufacturers? -- 76.209.28.72 05:43, 13 June 2007 (UTC)
PhysicistQuery 17:50, 20 July 2007 (UTC)If you look at the load presented by the oscillator to the crystal under steady-state conditions, it will consist of a negative resistance in series or in parallel with a reactance. The negative resistance will provide the energy needed to overcome the losses in the crystal; the reactance shifts the resonant frequency.
At the present time, the most common configuration for "simple" oscillators is the Pierce configuration, largely because all its elements can be integrated, and it naturally provides an output that is approximately symmetrical between the rails. This makes it convenient for a simple logic buffer to provide a rail-to-rail output suitable for driving digital systems. The reactance of the Pierce oscillator is naturally capacitive, and this is why the crystal is specified with a capacitive load (a pedantic point, but the circuit configuration of a Pierce circuit essentially provides negative impedance and capacitance in series - the "parallel" here refers only to a historic measurement method for the crystal that used a parallel capacitor). The Pierce oscillator can be modified using an external inductor in series with the crystal so that it is operated at series resonance, but this is seldom desirable except when it is necessary to tune the crystal.
An 'ideal' cross-coupled oscillator would ideally operate at series resonance, but in practice stray capacitances are inverted such that the majority of integrated circuit designs provide an inductive load to the crystal. If these oscillators are allowed to limit, the effective series inductance can become quite large.
"Each new distinct crystal source needs to be rigorously justified, since each one introduces new, difficult to debug probabilistic failure modes, due to multiple crystal interactions, into equipment."
Thats a new one on me. What is the failure mode, in what way do the xtals interact? Tabby ( talk) 23:39, 22 December 2007 (UTC)
Does anyone know what 20MHz crystal oscillators are used for? If so, please add to the table. Thanks. Pi.1415926535 ( talk) 15:05, 20 April 2008 (UTC)
20MHz crystals are used for 10Mbit/s ethernet, which uses a 20MHz clock and Manchester encoding. I've added it to the table. Glenn Anderson ( talk) 00:50, 7 January 2009 (UTC)
why are 33.33 MHz and 40 MHz mentioned but not on the list? what are they for? 09:26, 2 March 2009 (UTC)
The link, as well as the associated title, in reference 4 is the same as that of reference 2. The only difference is that reference 4 provides more title detail. This artificially inflates the number of references. MVD ( talk) 17:03, 23 March 2009 (UTC)
The hyperlink for the article The Evolution of the Quartz Crystal Clock by Warren A. Marrison has gone stale. The corrected link is as follows:
http://www.ieee-uffc.org/main/history.asp?file=marrison
I don't know how to edit the list of references, hopefully some enterprising admin will pick up this torch and run with it. —Preceding unsigned comment added by 72.13.210.165 ( talk) 03:08, 17 April 2009 (UTC)
Used in VCXO for DSL applications. —Preceding unsigned comment added by 24.205.237.171 ( talk) 21:41, 22 October 2009 (UTC)
You can get a quartz crystal ground for any frequency. The Digi Key on-line catalog lists more than 400 frequencies. The listing isn't very useful - there's a number of reasons to pick any particular freqeuncy and there's no general significance in any particular numeric value, let alone a list of hundreds. It's of no encyclopediac value to say the Binford 6100 used a 16.123 MHZ crystal while the sucessor model used a 16.321 MHZ clock unless this detail was actually significant. -- Wtshymanski ( talk) 21:02, 7 December 2009 (UTC)
Agree that the frequency list is not interesting as it stands. A list of "standard application" frequencies that gave a bit of background might be - but should probably be a separate page, and would include frequencies that are not directly related to crystals. BTW, the references to 32 kHz are perhaps less irritating than including the irrelevant precision - but maybe they should merely be described as "watch crystals" except in a single place where 32768Hz is given as a commonly used frequency for these? PhysicistQuery ( talk) 12:19, 22 December 2010 (UTC)
What does it mean: SPXO? Regards -- Elcap ( talk) 17:04, 14 September 2010 (UTC)
AT cut crystal: The description of frequency-temperature shape of the AT cut as "sine" is misleading. Third order would be correct. This seems to be a case where a picture would be worth a thousand words. PhysicistQuery ( talk) 11:56, 22 December 2010 (UTC)
SC cut crystal: The statement "coupled modes are worse than the AT" does not seem to be borne out in practice. Indeed, the performance of the MCXO relies on the excursions due to coupled modes being very small. Would the author perhaps be referring to the requirement to suppress the (usually more active) B-mode vibration at (about) 10% lower frequency than the wanted frequency? This is not at all the same thing as a coupled mode. BTW, coupled modes are not described/defined anywhere in the article, so this reference is anyway meaningless to general readers PhysicistQuery ( talk) 11:56, 22 December 2010 (UTC) Similarly, the temperature sensitivity (third-order coefficient) of the SC is quite similar to the AT. Because of the high inflection temperature, however, the temperature sensitivity of an SC cut crystal can be made relatively small for use in an ovened oscillator. On the other hand, the frequency-temperature sensitivity for temperature ranges that are centred near "normal" temperature is considerably greater for an SC cut than for an AT. PhysicistQuery ( talk) 12:04, 22 December 2010 (UTC)