Re: [time-nuts] Bye-Bye Crystals
artgodwin@gmail.com said:
I'm not after quality - I do have an application in mind but it doesn't need
to compete with mass production. Just wondering if it's feasible to make
something crude that will resonate.
Are you doing this for fun or ???
Feasible? Sure. Cheaper? That depends.
The cost difference between a complete oscillator package and a simple
crystal is tiny. The osc is often cheaper if you include board space or
engineering time.
Is your background digital or analog? Do you want a sine wave or a clock?
My background is primarily digital. If the chip you are using has 2 pins
setup to drive a crystal, you can probably get it to run reliably by
following the data sheet and/or app notes. The usual recipe is 2 tiny caps
and a big resistor. (big in resistance, not physically big)
An advantage of using a crystal with the on-chip amplifier that I didn't
mention last time is that you save the osc power if you power down that
corner of the chip.
If you want a sine wave, you are out of my comfort zone. I'd probably look
in ham radio literature.
They make logic chips like a 74HCU04, U for unbuffered. One of their uses is
for making oscillators. I've never done it. Try google.
--
These are my opinions. I hate spam.
For interest, and as part of art project involving crystals. I want to show
a less third-age usage than is common in that space :).Acceleration effect
on frequency may also be featured. No way would I do it for cost or quality.
Like you, I normally use packaged oscillators for most things - though I do
still encounter plenty of the passive crystals on cheap microprocessor
boards. The oscillators may be $1, but I suspect those crystals are 10c.
My first encounters with crystals were probably with the inverter
oscillators of early micros. I gather there's a lot more black magic in
their design than analysis, and as a result they used to have problems
oscillating. The oscillators built into modern micros are a lot better.
I'll probably use a more carefully characterised amplifier if i cut my own
crystal.
On Tue, Mar 14, 2017 at 8:44 AM, Hal Murray hmurray@megapathdsl.net wrote:
artgodwin@gmail.com said:
I'm not after quality - I do have an application in mind but it doesn't
need
to compete with mass production. Just wondering if it's feasible to make
something crude that will resonate.
Are you doing this for fun or ???
Feasible? Sure. Cheaper? That depends.
The cost difference between a complete oscillator package and a simple
crystal is tiny. The osc is often cheaper if you include board space or
engineering time.
Is your background digital or analog? Do you want a sine wave or a clock?
My background is primarily digital. If the chip you are using has 2 pins
setup to drive a crystal, you can probably get it to run reliably by
following the data sheet and/or app notes. The usual recipe is 2 tiny caps
and a big resistor. (big in resistance, not physically big)
An advantage of using a crystal with the on-chip amplifier that I didn't
mention last time is that you save the osc power if you power down that
corner of the chip.
If you want a sine wave, you are out of my comfort zone. I'd probably look
in ham radio literature.
They make logic chips like a 74HCU04, U for unbuffered. One of their uses
is
for making oscillators. I've never done it. Try google.
--
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.
For a sinewave oscillator
http://www.wenzel.com/wp-content/uploads/xtalosc.pdf
is a start for fundamental crystals.
However the npn transistor operates a little too close to saturation for my liking.
A small change to the biasing of the npn will fix this.
With overtone crystal operation mode suppression is necessary to ensure the crystal operates on the desired overtone.
Amateur literature on crystal oscillators and even LC oscillators includes quite a few relatively poor circuits.
Looking at oscillator circuits like the HP10811A will give some idea of some of the additional complexity required for a overtone operation. Dissecting a few ocxos may also be helpful. Some start with a 10MHz crystal and a Colpitts sustaining stage and use a 74HC74 or similar to divide the 10Mhz by 2 and drive the output pin. Even when a sinewave output is required often a CMOS inverter drives the output pin via an LC filter.
Bruce
On 14 March 2017 at 21:44 Hal Murray <hmurray@megapathdsl.net> wrote:
artgodwin@gmail.com said:
I'm not after quality - I do have an application in mind but it doesn't need
to compete with mass production. Just wondering if it's feasible to make
something crude that will resonate.
Are you doing this for fun or ???
Feasible? Sure. Cheaper? That depends.
The cost difference between a complete oscillator package and a simple
crystal is tiny. The osc is often cheaper if you include board space or
engineering time.
Is your background digital or analog? Do you want a sine wave or a clock?
My background is primarily digital. If the chip you are using has 2 pins
setup to drive a crystal, you can probably get it to run reliably by
following the data sheet and/or app notes. The usual recipe is 2 tiny caps
and a big resistor. (big in resistance, not physically big)
An advantage of using a crystal with the on-chip amplifier that I didn't
mention last time is that you save the osc power if you power down that
corner of the chip.
If you want a sine wave, you are out of my comfort zone. I'd probably look
in ham radio literature.
They make logic chips like a 74HCU04, U for unbuffered. One of their uses is
for making oscillators. I've never done it. Try google.
--
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.
Hi
On Mar 14, 2017, at 4:44 AM, Hal Murray hmurray@megapathdsl.net wrote:
artgodwin@gmail.com said:
I'm not after quality - I do have an application in mind but it doesn't need
to compete with mass production. Just wondering if it's feasible to make
something crude that will resonate.
Are you doing this for fun or ???
Feasible? Sure. Cheaper? That depends.
The cost difference between a complete oscillator package and a simple
crystal is tiny. The osc is often cheaper if you include board space or
engineering time.
Purchased in volume, the difference it the price of a crystal vs a complete XO
is enormous. You will see at least a 10:1 cost savings on the crystal and likely
more than that. Simply attaching a crystal to the internal oscillator inside a
chip is nearly zero engineering cost. If your product is cost sensitive and
not super tight tolerance … you go with the crystal.
Bob
Is your background digital or analog? Do you want a sine wave or a clock?
My background is primarily digital. If the chip you are using has 2 pins
setup to drive a crystal, you can probably get it to run reliably by
following the data sheet and/or app notes. The usual recipe is 2 tiny caps
and a big resistor. (big in resistance, not physically big)
An advantage of using a crystal with the on-chip amplifier that I didn't
mention last time is that you save the osc power if you power down that
corner of the chip.
If you want a sine wave, you are out of my comfort zone. I'd probably look
in ham radio literature.
They make logic chips like a 74HCU04, U for unbuffered. One of their uses is
for making oscillators. I've never done it. Try google.
--
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.
On 3/14/17 5:04 AM, Bob Camp wrote:
Hi
The cost difference between a complete oscillator package and a simple
crystal is tiny. The osc is often cheaper if you include board space or
engineering time.
Purchased in volume, the difference it the price of a crystal vs a complete XO
is enormous. You will see at least a 10:1 cost savings on the crystal and likely
more than that. Simply attaching a crystal to the internal oscillator inside a
chip is nearly zero engineering cost. If your product is cost sensitive and
not super tight tolerance … you go with the crystal.
And that crystal business (gazillions of inexpensive 16 MHz crystals) is
very different from making an approximately 12 MHz crystal used in a
VCXO that will be FMed and multiplied up by 36 to make a 430 MHz
transmitter, oh, and that matches whatever temperature compensation
scheme GE used in 1970.
Hi
On Mar 14, 2017, at 8:49 AM, jimlux jimlux@earthlink.net wrote:
On 3/14/17 5:04 AM, Bob Camp wrote:
Hi
The cost difference between a complete oscillator package and a simple
crystal is tiny. The osc is often cheaper if you include board space or
engineering time.
Purchased in volume, the difference it the price of a crystal vs a complete XO
is enormous. You will see at least a 10:1 cost savings on the crystal and likely
more than that. Simply attaching a crystal to the internal oscillator inside a
chip is nearly zero engineering cost. If your product is cost sensitive and
not super tight tolerance … you go with the crystal.
And that crystal business (gazillions of inexpensive 16 MHz crystals) is very different from making an approximately 12 MHz crystal used in a VCXO that will be FMed and multiplied up by 36 to make a 430 MHz transmitter, oh, and that matches whatever temperature compensation scheme GE used in 1970.
Well, what GE did in 1970 was to test every single assembly over temperature (multiple times)
and pick parts for that specific assembly to compensate it. There never was a magic single crystal
design to match the compensation in a given unit ….
Bob
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.
not to mention +/- a few hundred ppm is not a big deal.
You can always correct for it in software. ;)
On Tue, Mar 14, 2017 at 8:49 AM, jimlux jimlux@earthlink.net wrote:
On 3/14/17 5:04 AM, Bob Camp wrote:
Hi
The cost difference between a complete oscillator package and a simple
crystal is tiny. The osc is often cheaper if you include board space or
engineering time.
Purchased in volume, the difference it the price of a crystal vs a
complete XO
is enormous. You will see at least a 10:1 cost savings on the crystal and
likely
more than that. Simply attaching a crystal to the internal oscillator
inside a
chip is nearly zero engineering cost. If your product is cost sensitive
and
not super tight tolerance … you go with the crystal.
And that crystal business (gazillions of inexpensive 16 MHz crystals) is
very different from making an approximately 12 MHz crystal used in a VCXO
that will be FMed and multiplied up by 36 to make a 430 MHz transmitter,
oh, and that matches whatever temperature compensation scheme GE used in
1970.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/m
ailman/listinfo/time-nuts
and follow the instructions there.
On 3/14/2017 4:03 AM, Bruce Griffiths wrote:
Looking at oscillator circuits like the HP10811A will give some idea of some of the additional complexity required for a overtone operation. Dissecting a few ocxos may also be helpful. Some start with a 10MHz crystal and a Colpitts sustaining stage and use a 74HC74 or similar to divide the 10Mhz by 2 and drive the output pin. Even when a sinewave output is required often a CMOS inverter drives the output pin via an LC filter.
Bruce
I don't agree here. The 10811 is not a good tutorial for general
oscillator design. Because it is SC cut, it has a complicated
mode suppression network across the base emitter junction to
suppress mode B as well as the fundamental.
The E1983A oscillator uses the same crystal (in a low profile
package). You can read my paper about it and see that I
used a very simple bridged tee oscillator circuit. That is
all you need to select the right overtone and mode.
This is the same circuit that I used at Zeta Labs 40 years
ago to design hundreds of custom VCXO's, up to the 9th
overtone. It simply worked every time, unlike various other
designs that were in use at Zeta.
Around 1985, I got a consulting gig at Equatorial Communications
to redesign their 5th overtone VCXO. Only about half of the
crystals would work in their circuit. They had thousands
of "reject" crystals. I just used my old Zeta circuit and
all the crystals started working again.
Equatorial owned the 10 meter dish that you used to see on
your right going south on 237 just before passing over
Central Expressway in Mountain View.
Rick N6RK
Not only that. Good luck finding a datasheet with any analog
specifications for its internal oscillator. Here are the pins for an
external crystal. The microchip PICs are nice, they give you the goldilocks
selection for drive level a little cool, a little hot, maybe just right.
On Tue, Mar 14, 2017 at 8:04 AM, Bob Camp kb8tq@n1k.org wrote:
Hi
On Mar 14, 2017, at 4:44 AM, Hal Murray hmurray@megapathdsl.net wrote:
artgodwin@gmail.com said:
I'm not after quality - I do have an application in mind but it doesn't
need
to compete with mass production. Just wondering if it's feasible to make
something crude that will resonate.
Are you doing this for fun or ???
Feasible? Sure. Cheaper? That depends.
The cost difference between a complete oscillator package and a simple
crystal is tiny. The osc is often cheaper if you include board space or
engineering time.
Purchased in volume, the difference it the price of a crystal vs a
complete XO
is enormous. You will see at least a 10:1 cost savings on the crystal and
likely
more than that. Simply attaching a crystal to the internal oscillator
inside a
chip is nearly zero engineering cost. If your product is cost sensitive
and
not super tight tolerance … you go with the crystal.
Bob
Is your background digital or analog? Do you want a sine wave or a
clock?
My background is primarily digital. If the chip you are using has 2 pins
setup to drive a crystal, you can probably get it to run reliably by
following the data sheet and/or app notes. The usual recipe is 2 tiny
caps
and a big resistor. (big in resistance, not physically big)
An advantage of using a crystal with the on-chip amplifier that I didn't
mention last time is that you save the osc power if you power down that
corner of the chip.
If you want a sine wave, you are out of my comfort zone. I'd probably
look
in ham radio literature.
They make logic chips like a 74HCU04, U for unbuffered. One of their
uses is
for making oscillators. I've never done it. Try google.
--
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.
In my design I need 10ppM, and then I divide by 8. Software can't correct for anything.
-----Original Message-----
From: time-nuts [mailto:time-nuts-bounces@febo.com] On Behalf Of Bob Bownes
Sent: Tuesday, March 14, 2017 10:50 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Bye-Bye Crystals
not to mention +/- a few hundred ppm is not a big deal.
You can always correct for it in software. ;)
On Tue, Mar 14, 2017 at 8:49 AM, jimlux jimlux@earthlink.net wrote:
On 3/14/17 5:04 AM, Bob Camp wrote:
Hi
The cost difference between a complete oscillator package and a
simple
crystal is tiny. The osc is often cheaper if you include board
space or engineering time.
Purchased in volume, the difference it the price of a crystal vs a
complete XO is enormous. You will see at least a 10:1 cost savings on
the crystal and likely more than that. Simply attaching a crystal to
the internal oscillator inside a chip is nearly zero engineering
cost. If your product is cost sensitive and not super tight
tolerance … you go with the crystal.
And that crystal business (gazillions of inexpensive 16 MHz crystals)
is very different from making an approximately 12 MHz crystal used in
a VCXO that will be FMed and multiplied up by 36 to make a 430 MHz
transmitter, oh, and that matches whatever temperature compensation
scheme GE used in 1970.
time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to
https://www.febo.com/cgi-bin/m ailman/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.