[time-nuts] Bye-Bye Crystals
Bob Camp
kb8tq at n1k.org
Tue Mar 14 12:04:40 UTC 2017
Hi
> On Mar 14, 2017, at 4:44 AM, Hal Murray <hmurray at megapathdsl.net> wrote:
>
>
> artgodwin at 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.
>
>
>
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