Quartz crystal motional parameters, and how to measure them
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- čas přidán 15. 05. 2016
- A discussion on crystal motional parameters and how to measure them using a Saunders 150B crystal impedance meter, plus some hard data on the typical motional parameters and Q values of over 150 crystals ranging from 1-40MHz. Raw data and some additional stats at: www.analogzoo.com/2016/05/crys...
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Sure wish you’d come back and make more of these great videos ❤
I am rather jealous of you having all those crystals available to you.0:07. I have a few modern ones which I used for my Radio Control ar 27 megs ( harmonic) and only TWO old navy crystals which I treasure. I built circuits for them so that I can see them just oscillating. On their own , the output waveform is not purely sinusoidal but the idea of me returning to the good old days when valves were warm and glowed, it adds a little nostalgia to my life.
Nice work you do, Congratulations.
This video cleared multiple questions I had with regard to crystal filter design, THANKS !
I hope you continue to make more videos !!!
Great video! You are excellent at presenting this stuff.
this was so clear and super helpful!!!
Thanks, this is a great video!
PERL captions... awesome!
Did you ever measure one of the 32768Hz crystals for RTC? What are their typical parameters?
I am trying to build a 32768Hz tone detector with such crystal and I am kind of stumped because my VNA shows -50dB in the passband and -80dB in the stopband when swept as suggested in your video. ...while using 50 Ohm I/O
It`s a very good to have such an equipment! But what if I have only a DDS generator and an oscilloscope?
Hi, your videos about the quartz crystal are really illustrating. Do you know if the lithium niobate crystal (usually used in transducers) has the same equivalent circuit as the quartz crystal? Thank you!
I've never worked with them, but being piezoelectric like quartz I would expect the equivalent circuit to be the same. It's a bit old, but this handbook seems to have quite a bit of information on the subject of transducer analysis and equivalent circuits: www.dtic.mil/dtic/tr/fulltext/u2/a082503.pdf
Can you please provide any data on that USSR-produced oscillator? May be photo of the manufacturers markings on it? Would be interesting to investigate a bit.
+SLEAGD I’ve uploaded a few pictures here: analogzoo.com/xtal_pics/. The markings on the crystal are: “5128K 8607 94”. The 5128K is the frequency (5.128MHz) and I presume 8607 is a date code. There is also what appears to be a logo stamped on it that I haven’t been able to identify. If it helps, this is the eBay seller I bought it from: www.ebay.com/usr/bird_sr71a. I’d love to hear about any info you might find on it!
+devttys0
Manufacturer is identifiable from the logo. Oddly enough, they are still in business: www.morion.com.ru
A few interesting examples of USSR-made quartz crystal resonators in the glass envelop could be found here 155la3.ru/quartz_glass.htm
There are lots of other interesting soviet electronics related stuff there.
Package type and resonant frequency range of your crystal matches resonator type
РК-187 (RK-187). According to general databook this is rather high spec. part. It operates at 7-th harmonic,
4.6-5.3MHz crystals of this type were available,
tuning precision is +-(0.4..2.0)10^{-6},
temp. coefficient +-0.05ppm/K (incredible performance, can you please confirm it for your crystal?)
rated Q>1.5x10^6
+SLEAGD Very cool, thanks for tracking all that down! Those specs are very impressive, it sounds like I'll have to do a follow-up video on just this crystal.
Hi may I know what is the Textbook being used here ?
You describe adding capacitance in parallel to the Co of the crystal. Is that what the knob labelled SERIES CAPACITOR does ?
When you depress the "Ct" switch, yes, the variable capacitance is placed in parallel with the crystal and the total capacitance is measured. You can then just subtract the known variable capacitance value from the total to get the Co capacitance.
How does one know the variable capacitance value when the knob has no calibration?
If you press the Ct switch with no crystal in place, the displayed capacitance will be only that of the variable capacitor.
You can see an example of this at 5:08 in the video
Yes, I see. The display implies 0.01pF resolution though I doubt that the last digit is stable over time. I would label the knob PARALLEL not SERIAL capacitance.
nice
Hello sir
What is y parameter
I try to simulate that 5MHz crystal in LTSpice with parameters you measured and... crystal resonate at 10MHz :?
fs=9.9987489MHz, fp=10.018856MHz
+rapsod1911 You're correct, the inductance should read 62.949mH; see my reply to Dennis Lubert. Thanks!
are those floppy disks????
+Susan Donovan I was wondering if someone would notice those. :)
Pfft... little floppies. 8" or bust!
What is unloaded Q qualitatively? Is it related to stability, narrowness of the frequency response (this is my guess due to the phase noise comment), etc? I don't have a good feel for what it's "good" for :)
+hpux735 It is called "quality" (hence Q) of resonator. You can think of it as a number of oscillations in which amplitude will decay by e-fold if oscillator will be left alone. It is also related to narrowness of frequency response (delta f /f ~ 1/Q)
+hpux735 "Q" (or quality factor) is a unit-less quantity that is simply the ratio of stored energy (reactance) to dissipated energy (resistance). Ideal components such as inductors, capacitors, and crystals would be purely reactive with no resistive losses, and hence have an infinite Q. In the real world of course this is not possible, so limiting the resistive losses (and therefore increasing the Q) is a major design/manufacturing goal.
You're absolutely correct, the Q does effect frequency response / stability. A higher Q (less resistive loss) would mean a sharper filter response or less oscillator phase noise. Inductors in particular are difficult in this respect because a coil of wire has some unavoidable inherent resistance; this is exacerbated at RF frequencies by the skin effect and can make realizing sharp filters with low passband losses difficult or impossible. The relatively low resistive losses of a quartz crystal then makes it preferable to an LC circuit in situations where high performance is required.
+devttys0 +SLEAGD Thanks! I'm used to hearing about Q of inductors, etc, but didn't know how it mapped to crystals. This was a very cool video, thanks!