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3.57MHz crystals — Parallax Forums

3.57MHz crystals

ArchiverArchiver Posts: 46,084
edited 2002-06-21 23:09 in General Discussion
Hi. I have a project that requires decoding DTMF tones for decision
making. I'm using a BS2 and California Microdevices CM8880.

I see that the CM8880 requires a 3.5795MHz crystal to operate. As
luck would have it, I only have a 35MHz crystal.

My question is, what does a crystal do? I understand that it
vibrates, but what is its purpose and how are its oscillations
measured? Three years studying Computer Engineering, and I've never
had to use one. I'm looking for some background on it.

Thanks alot!

Comments

  • ArchiverArchiver Posts: 46,084
    edited 2002-06-20 04:58
    You won't be able to make that substitution. A crystal is like a very
    high-quality LCR (inductance/capacitance/resistor) circuit. So you can
    think of it as a tuned circuit with a very high Q. Primarily, in this
    world, we use them to set the frequency of an oscillator. However, in
    other parts of the business they are also used a filter elements.

    3.5795 is the "colorburst" frequency used in color television so there
    is a high volume of these crystals produced and they are cheap.

    Al Williams
    AWC
    * Floating point A/D
    http://www.al-williams.com/awce/pak9.htm


    >
    Original Message
    > From: iamlevis2 [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=f8jqeBULK1BXfA9gnLq2T4GPeAc9U6wdx1QIiN9EuJooEJi-iOHy6Rc_QG2BR5zYPbgUzESuJ7mKgkHaUl4Pmg]stampslist@l...[/url
    > Sent: Wednesday, June 19, 2002 10:16 PM
    > To: basicstamps@yahoogroups.com
    > Subject: [noparse][[/noparse]basicstamps] 3.57MHz crystals
    >
    >
    > Hi. I have a project that requires decoding DTMF tones for decision
    > making. I'm using a BS2 and California Microdevices CM8880.
    >
    > I see that the CM8880 requires a 3.5795MHz crystal to operate. As
    > luck would have it, I only have a 35MHz crystal.
    >
    > My question is, what does a crystal do? I understand that it
    > vibrates, but what is its purpose and how are its oscillations
    > measured? Three years studying Computer Engineering, and I've never
    > had to use one. I'm looking for some background on it.
    >
    > Thanks alot!
    >
    >
    > To UNSUBSCRIBE, just send mail to:
    > basicstamps-unsubscribe@yahoogroups.com
    > from the same email address that you subscribed. Text in the
    > Subject and Body of the message will be ignored.
    >
    >
    > Your use of Yahoo! Groups is subject to
    > http://docs.yahoo.com/info/terms/
    >
  • ArchiverArchiver Posts: 46,084
    edited 2002-06-20 06:18
    Ok. And is a crystal the same as a resonator?


    --- In basicstamps@y..., "Al Williams" <alw@a...> wrote:
    > You won't be able to make that substitution. A crystal is like a
    very
    > high-quality LCR (inductance/capacitance/resistor) circuit. So you
    can
    > think of it as a tuned circuit with a very high Q. Primarily, in
    this
    > world, we use them to set the frequency of an oscillator. However,
    in
    > other parts of the business they are also used a filter elements.
    >
    > 3.5795 is the "colorburst" frequency used in color television so
    there
    > is a high volume of these crystals produced and they are cheap.
    >
    > Al Williams
    > AWC
    > * Floating point A/D
    > http://www.al-williams.com/awce/pak9.htm
    >
    >
    > >
    Original Message
    > > From: iamlevis2 [noparse][[/noparse]mailto:stampslist@l...]
    > > Sent: Wednesday, June 19, 2002 10:16 PM
    > > To: basicstamps@y...
    > > Subject: [noparse][[/noparse]basicstamps] 3.57MHz crystals
    > >
    > >
    > > Hi. I have a project that requires decoding DTMF tones for
    decision
    > > making. I'm using a BS2 and California Microdevices CM8880.
    > >
    > > I see that the CM8880 requires a 3.5795MHz crystal to operate. As
    > > luck would have it, I only have a 35MHz crystal.
    > >
    > > My question is, what does a crystal do? I understand that it
    > > vibrates, but what is its purpose and how are its oscillations
    > > measured? Three years studying Computer Engineering, and I've
    never
    > > had to use one. I'm looking for some background on it.
    > >
    > > Thanks alot!
    > >
    > >
    > > To UNSUBSCRIBE, just send mail to:
    > > basicstamps-unsubscribe@y...
    > > from the same email address that you subscribed. Text in the
    > > Subject and Body of the message will be ignored.
    > >
    > >
    > > Your use of Yahoo! Groups is subject to
    > > http://docs.yahoo.com/info/terms/
    > >
  • ArchiverArchiver Posts: 46,084
    edited 2002-06-20 13:37
    Well, they have the same function. A crystal is made by cutting a piece
    of quartz crystal (which is interesting all by itself -- how it is cut
    determines many of its properties). A resonator is typically made from a
    ceramic material. Resonators are more rugged and frequently less
    expensive, but not as stable or accurate as a crystal.

    You might find this article illuminating:
    http://www.piclist.com/techref/microchip/osc.htm


    Al Williams
    AWC
    * Floating point math for the Stamp, PIC, SX, or any microcontroller
    http://www.al-williams.com/awce/pak1.htm



    >
    Original Message
    > From: iamlevis2 [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=E6o7qYTW5tKcLiNCOYwsOex0xu1hlcUuro516BeRoYfxGvsjW4GLfFz5293lDqftupMMeZ6-FfR-ooL4HOfkfwsHg8bs]stampslist@l...[/url
    > Sent: Thursday, June 20, 2002 12:19 AM
    > To: basicstamps@yahoogroups.com
    > Subject: [noparse][[/noparse]basicstamps] Re: 3.57MHz crystals
    >
    >
    > Ok. And is a crystal the same as a resonator?
    >
    >
    > --- In basicstamps@y..., "Al Williams" <alw@a...> wrote:
    > > You won't be able to make that substitution. A crystal is like a
    > very
    > > high-quality LCR (inductance/capacitance/resistor) circuit. So you
    > can
    > > think of it as a tuned circuit with a very high Q. Primarily, in
    > this
    > > world, we use them to set the frequency of an oscillator. However,
    > in
    > > other parts of the business they are also used a filter elements.
    > >
    > > 3.5795 is the "colorburst" frequency used in color television so
    > there
    > > is a high volume of these crystals produced and they are cheap.
    > >
    > > Al Williams
    > > AWC
    > > * Floating point A/D http://www.al-williams.com/awce/pak9.htm
    > >
    > >
    > > >
    Original Message
    > > > From: iamlevis2 [noparse][[/noparse]mailto:stampslist@l...]
    > > > Sent: Wednesday, June 19, 2002 10:16 PM
    > > > To: basicstamps@y...
    > > > Subject: [noparse][[/noparse]basicstamps] 3.57MHz crystals
    > > >
    > > >
    > > > Hi. I have a project that requires decoding DTMF tones for
    > decision
    > > > making. I'm using a BS2 and California Microdevices CM8880.
    > > >
    > > > I see that the CM8880 requires a 3.5795MHz crystal to
    > operate. As
    > > > luck would have it, I only have a 35MHz crystal.
    > > >
    > > > My question is, what does a crystal do? I understand that it
    > > > vibrates, but what is its purpose and how are its oscillations
    > > > measured? Three years studying Computer Engineering, and I've
    > never
    > > > had to use one. I'm looking for some background on it.
    > > >
    > > > Thanks alot!
    > > >
    > > >
    > > > To UNSUBSCRIBE, just send mail to:
    > > > basicstamps-unsubscribe@y...
    > > > from the same email address that you subscribed. Text in the
    > > > Subject and Body of the message will be ignored.
    > > >
    > > >
    > > > Your use of Yahoo! Groups is subject to
    > > > http://docs.yahoo.com/info/terms/
    > > >
    >
    >
    > To UNSUBSCRIBE, just send mail to:
    > basicstamps-unsubscribe@yahoogroups.com
    > from the same email address that you subscribed. Text in the
    > Subject and Body of the message will be ignored.
    >
    >
    > Your use of Yahoo! Groups is subject to
    http://docs.yahoo.com/info/terms/
  • ArchiverArchiver Posts: 46,084
    edited 2002-06-20 22:36
    --- Al Williams <alw@a...> wrote:
    > 3.5795 is the "colorburst" frequency used in color
    > television so there
    > is a high volume of these crystals produced and they
    > are cheap.

    Radio Shack used to (And still should) stock that
    particular crystal.

    Chris


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  • ArchiverArchiver Posts: 46,084
    edited 2002-06-21 23:09
    Last question: do you think it would be safe to use a resonator in
    place of a crystal, if their frequencies match? I'm deciding between
    a 3.58 ceramic resonator, or a 3.5795 crystal... It's for a DTMF
    decoder IC (Specifically, the CM-8880)

    Thanks for all the help...

    >
    Original Message
    > From: Al Williams [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=tOCgieyr5jLBb3EsVeYx02PB3S3ltLvCVg51ImXswFtpBCvfgoAnvpbOSOPn2QvujY5Iwo0HFya04w]alw@a...[/url
    > Posted At: Thursday, June 20, 2002 8:37 AM
    > Posted To: StampsList
    > Conversation: [noparse][[/noparse]basicstamps] Re: 3.57MHz crystals
    > Subject: RE: [noparse][[/noparse]basicstamps] Re: 3.57MHz crystals
    >
    >
    > Well, they have the same function. A crystal is made by
    > cutting a piece of quartz crystal (which is interesting all
    > by itself -- how it is cut determines many of its
    > properties). A resonator is typically made from a ceramic
    > material. Resonators are more rugged and frequently less
    > expensive, but not as stable or accurate as a crystal.
    >
    > You might find this article illuminating:
    > http://www.piclist.com/techref/microchip/osc.htm
    >
    >
    > Al Williams
    > AWC
    > * Floating point math for the Stamp, PIC, SX, or any
    > microcontroller http://www.al-williams.com/awce/pak1.htm
    >
    >
    >
    > >
    Original Message
    > > From: iamlevis2 [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=l9QuS-fcz5bUTtFbqENcKRCvVvWfOU3QVwaOV_Oao8qRc4uzH9-3mnR_NL1kBp001nGcrpveJJAzfzLi-sZMtEPFbRcg]stampslist@l...[/url
    > > Sent: Thursday, June 20, 2002 12:19 AM
    > > To: basicstamps@yahoogroups.com
    > > Subject: [noparse][[/noparse]basicstamps] Re: 3.57MHz crystals
    > >
    > >
    > > Ok. And is a crystal the same as a resonator?
    > >
    > >
    > > --- In basicstamps@y..., "Al Williams" <alw@a...> wrote:
    > > > You won't be able to make that substitution. A crystal is like a
    > > very
    > > > high-quality LCR (inductance/capacitance/resistor) circuit. So
    you
    > > can
    > > > think of it as a tuned circuit with a very high Q. Primarily, in
    > > this
    > > > world, we use them to set the frequency of an oscillator.
    However,
    > > in
    > > > other parts of the business they are also used a filter
    elements.
    > > >
    > > > 3.5795 is the "colorburst" frequency used in color television so
    > > there
    > > > is a high volume of these crystals produced and they are cheap.
    > > >
    > > > Al Williams
    > > > AWC
    > > > * Floating point A/D http://www.al-williams.com/awce/pak9.htm
    > > >
    > > >
    > > > >
    Original Message
    > > > > From: iamlevis2 [noparse][[/noparse]mailto:stampslist@l...]
    > > > > Sent: Wednesday, June 19, 2002 10:16 PM
    > > > > To: basicstamps@y...
    > > > > Subject: [noparse][[/noparse]basicstamps] 3.57MHz crystals
    > > > >
    > > > >
    > > > > Hi. I have a project that requires decoding DTMF tones for
    > > decision
    > > > > making. I'm using a BS2 and California Microdevices CM8880.
    > > > >
    > > > > I see that the CM8880 requires a 3.5795MHz crystal to
    > > operate. As
    > > > > luck would have it, I only have a 35MHz crystal.
    > > > >
    > > > > My question is, what does a crystal do? I understand that it
    > > > > vibrates, but what is its purpose and how are its
    oscillations
    > > > > measured? Three years studying Computer Engineering, and I've
    > > never
    > > > > had to use one. I'm looking for some background on it.
    > > > >
    > > > > Thanks alot!
    > > > >
    > > > >
    > > > > To UNSUBSCRIBE, just send mail to:
    > > > > basicstamps-unsubscribe@y...
    > > > > from the same email address that you subscribed. Text in the
    > > > > Subject and Body of the message will be ignored.
    > > > >
    > > > >
    > > > > Your use of Yahoo! Groups is subject to
    > > > > http://docs.yahoo.com/info/terms/
    > > > >
    > >
    > >
    > > To UNSUBSCRIBE, just send mail to:
    > > basicstamps-unsubscribe@yahoogroups.com
    > > from the same email address that you subscribed. Text in
    > the Subject
    > > and Body of the message will be ignored.
    > >
    > >
    > > Your use of Yahoo! Groups is subject to
    > http://docs.yahoo.com/info/terms/
    >
    >
    > To UNSUBSCRIBE, just send mail to:
    > basicstamps-unsubscribe@yahoogroups.com
    > from the same email address that you subscribed. Text in the
    > Subject and Body of the message will be ignored.
    >
    >
    > Your use of Yahoo! Groups is subject to
    > http://docs.yahoo.com/info/terms/
    >
    >
    >
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