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'[EE] resonator question'
2005\10\21@095857 by alan smith

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Since I have always used crytals or oscillators, I don't know alot about the ceramic resonators.  First, whats the difference between the 3 pin and 2 pin devices.  Second, for a colorburst frequency are they as stable as a crystal? certainly appears cheaper.



               
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2005\10\21@100717 by Michael Rigby-Jones

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>-----Original Message-----
>From: spam_OUTpiclist-bouncesTakeThisOuTspammit.edu [.....piclist-bouncesKILLspamspam@spam@mit.edu]
>Sent: 21 October 2005 14:59
>To: Microcontroller discussion list - Public.
>Subject: [EE] resonator question
>
>
>Since I have always used crytals or oscillators, I don't know
>alot about the ceramic resonators.  First, whats the
>difference between the 3 pin and 2 pin devices.  Second, for a
>colorburst frequency are they as stable as a crystal?
>certainly appears cheaper.

The 3 pin resonators have the loading caps built in (you just ground the center pin), so you don't need any other components.

They are not as stable as crystals and usualy their initial accuracy isn't as good.  They are however considerably more robust.

Regards

Mike

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2005\10\21@101808 by Spehro Pefhany

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At 06:58 AM 10/21/2005 -0700, you wrote:
>Since I have always used crytals or oscillators, I don't know alot about
>the ceramic resonators.

They start faster and are more rugged than crystals (both physically
and to overdrive), but are less accurate and less stable than crystals.
In many cases the latter is unimportant. Tolerance is typically something
like +/-0.5% maximum, and temperature stability is typically very good.

([AD] see my link bottom line for full data sheets on a few types that I sell)

>First, whats the difference between the 3 pin and 2 pin devices.

Three-pin devices have the load capacitors built-in so you can replace the
crystal and the two caps with a single part.

>Second, for a colorburst frequency are they as stable as a crystal?
>certainly appears cheaper.

Nowhere near as stable as most crystals, but they are more than good enough
for things like asynchronous serial communication. They are not acceptable
as the sole time reference for time-of-day clocks, but you could make an
excellent clock with battery backup if you have line frequency available.

You probably wouldn't want to use them as a reference for a frequency meter
either-- but they fill a gap in accuracy and stability between on-chip RC
oscillators and crystals, with few of the disadvantages of crystals.

Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speffspamKILLspaminterlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com
->> Inexpensive test equipment & parts http://search.ebay.com/_W0QQsassZspeff


2005\10\21@134239 by Bob Axtell

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Ceramic resonators are my preferred design standard. They are less
accurate than crystals, but they have MANY
advantages:

1. Stability has improved dramatically in recent years. Sealing the
resonator will solve most long-term drift effects. Ceramic resonators
are affected by moisture (as are crystals, but crystals are inherently
sealed well). Usually a simple semi-hard plastic coating after mounting
on the PCB will prevent long-term drift.

2. Incredible ability to handle physical shock. That's why NO TV remote
control uses a crystal- only ceramic resonators.

3. Easy to startup, impossible to accidentally oscillate at an overtone.
Just install it and forget it.

The 3-pin types contain their phase-shift caps builtin. No reason to
EVER buy 2-pin unless you plan to replace a crystal.

--Bob

 

alan smith wrote:

{Quote hidden}

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2005\10\22@090351 by alan smith

picon face
Thanks all.  So sounds like for my app....DTMF generator, resonator ought to work just fine.

Bob Axtell <EraseMEengineerspam_OUTspamTakeThisOuTcotse.net> wrote:Ceramic resonators are my preferred design standard. They are less
accurate than crystals, but they have MANY
advantages:

1. Stability has improved dramatically in recent years. Sealing the
resonator will solve most long-term drift effects. Ceramic resonators
are affected by moisture (as are crystals, but crystals are inherently
sealed well). Usually a simple semi-hard plastic coating after mounting
on the PCB will prevent long-term drift.

2. Incredible ability to handle physical shock. That's why NO TV remote
control uses a crystal- only ceramic resonators.

3. Easy to startup, impossible to accidentally oscillate at an overtone.
Just install it and forget it.

The 3-pin types contain their phase-shift caps builtin. No reason to
EVER buy 2-pin unless you plan to replace a crystal.

--Bob



alan smith wrote:

{Quote hidden}

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Note: To protect our network,
attachments must be sent to
attachspamspam_OUTengineer.cotse.net .
1-520-777-7606 USA/Canada
http://beam.to/azengineer

2005\10\22@124545 by olin piclist

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alan smith wrote:
> Since I have always used crytals or oscillators, I don't know alot
> about the ceramic resonators.  First, whats the difference between the
> 3 pin and 2 pin devices.

I see others have already answered this in detail.

> Second, for a colorburst frequency are they
> as stable as a crystal?

A normal TV colorburst requires higher accuracy than what a resonator can
deliver.  The circuit also needs to be able to pull the crystal to the
received color burst frequency and keep if phase locked to the color burst.
Ceramic resonators are not suitable for this job.


*****************************************************************
Embed Inc, embedded system specialists in Littleton Massachusetts
(978) 742-9014, http://www.embedinc.com

2005\10\22@140740 by alan smith

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Thanks...thats the other part of the answer i was looking for.

Olin Lathrop <@spam@olin_piclistKILLspamspamembedinc.com> wrote:alan smith wrote:
> Since I have always used crytals or oscillators, I don't know alot
> about the ceramic resonators. First, whats the difference between the
> 3 pin and 2 pin devices.

I see others have already answered this in detail.

> Second, for a colorburst frequency are they
> as stable as a crystal?

A normal TV colorburst requires higher accuracy than what a resonator can
deliver. The circuit also needs to be able to pull the crystal to the
received color burst frequency and keep if phase locked to the color burst.
Ceramic resonators are not suitable for this job.


*****************************************************************
Embed Inc, embedded system specialists in Littleton Massachusetts
(978) 742-9014, http://www.embedinc.com

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