DaveC ) writes:
On Sat, 16 Aug 2003 15:15:02 -0700, Asimov wrote
(in message ):

"Andrew Rossmann" bravely wrote to "All" (16 Aug 03 07:52:40)
--- on the topic of " "Y1" component designation?"

I don't thing the Y prefix is for a crystal. Like was stated I thought
it was for a resonnant filter, i.e ceramic or other type. These tend to
have 3 legs instead of a crystal's 2.

These resonnators are often used to replace a tuned coil because they
are a lot smaller, have a high Q, and can be more accurate without
requiring any tuning adjustment.

Now I (OP) am confused. It's not a crystal. I thought a ceramic resonator has
only 2 leads, while a filter has more(?)

But you say (I think you did...) that it is a filter.

Can you clarify a little?

I'm pretty sure I've seen Y1 to denote crystals, but for the life of
me I can't be certain. Of course! If nowhere else, the ARRL used Y1
to denote a crystal. Bill Orr's Radio Handbook used the same prefix.

Now, I'm not sure the circuit board designator would differentiate
between a crystal and a ceramic resonator. But since I just scrapped
a bunch of boards last week, I don't have anything handy to check.
So I think a manufacturer might use X or Y for the crystal, but
whatever they used, they'd use it for ceramic resonators.

Now for the issue of "filter". A lot of these oscillators use a pair
of capacitors from each side of the crystal (or ceramic resonator)
to ground:

------|Y1|---------
| |
C1 C2
|________|
ground

Not all oscillators, just the type you often see in digital equipment.

You'd need them whether Y1 was a crystal or a ceramic resonator.

Now, since that's the case, and ceramic resonators can include them,
you can get ceramic resonators with those two capacitors built in.
I would not call it a filter, but it would have three leads (the middle
one being ground). If you put one of those in where the capacitors
were already in place, you might not get good oscillation.

There are of course little ceramic things with three leads that are
indeed filters, as in IF filters. You can use those in oscillators,
I've seen circuits that sort of amount to novelty, but they are not
the same thing as the ceramic filters with the built in capacitors.

Now, if I remember your original post, it sure sounds like a ceramic
resonator. I'd say they are interchangeable with crystals (or vice
versa), given the issue of those external capacitors. If the
circuit expects a resonator with the capacitors, the crystal will
require external capacitors (because they will not be built in).
Ceramic resonators are cheaper to manufacture than crystals, and
not as good in performance as crystals. But for many applications,
the ceramic resonator is fine. Putting a crystal should be fine,
though the reverse situation might not be suitable (depending on
the specific application). There might be a few places where
the design requires the ceramic resonator, because I gather they
can be varied in frequency by changing load capacitors, more than
the average crystal. But that would be a specific exception.

If the thing has two leads only, then the issue of the extra
capacitors doesn't exist. Pull a crystal of the correct frequency
out of something, and there you go.

Michael