Need help with Crystal Oscillator circuit...

Thread Starter

fantaasia

Joined Aug 26, 2020
4
Hi,

I need the simplest circuit to run 250 crystal oscillators at once.
The circuit must give a sharp pulse to all the crystals at 1Hz.
The idea is the get them all "ring" and resonate with each other.
They are regular 32khz cylinder oscillators used in watches.

Any ideas?
 

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MrSalts

Joined Apr 2, 2020
22
Only if the table has significant "give". The tray the metronomes are on (specifically, the non-sturdy tray) is the key to this myth that could not be easily reproduced by everyone who had a collection of metronomes.

 

Papabravo

Joined Feb 24, 2006
14,398
Hi,

I need the simplest circuit to run 250 crystal oscillators at once.
The circuit must give a sharp pulse to all the crystals at 1Hz.
The idea is the get them all "ring" and resonate with each other.
They are regular 32khz cylinder oscillators used in watches.

Any ideas?
The resonant frequencies are not all the same and are sensitive to external component values and temperature. The best you can hope for is that, if they oscillate, they will all be in some ε-neighborhood of the expected resonant frequency. Will this be good enough?

So ±0.5% would be [32604.16, 32931.84 Hz] Will that be good enough?

Since they are all oscillating at different frequencies, there is no earthly way to synchronize them. Did you really expect that you could do this?
 
Last edited:

upand_at_them

Joined May 15, 2010
514
The resonant frequencies are not all the same and are sensitive to external component values and temperature. The best you can hope for is that, if they oscillate, they will all be in some ε-neighborhood of the expected resonant frequency. Will this be good enough?

So ±0.5% would be [32604.16, 32931.84 Hz] Will that be good enough?
A cheap watch crystal is 30ppm, which is 0.003%. But that's still 1 second out in about 9.26 hours. Good luck getting them to sync. Ha! And I'm wondering, even if one could get them all to sync, wouldn't the energy from the combined resonance damage the crystals?
 

MisterBill2

Joined Jan 23, 2018
6,998
If you have 250 individual oscillator circuits that are independent then you will have a bunch of frequencies fairly close. But a crystal oscillator is not an absolutely fixed frequency system. They are variable over some small range, and that is used to advantage in setting up crystal oscillators.
Ham radio folks have been doing that for years, "pulling" the frequency of a crystal oscillator several kilohertz.
If you are wanting to simply determine the exact natural frequency you will need to construct ONE oscillator and run each crystal, keeping all of the possible variables constant. AND you will need a very stable frequency measuring system, at least 10x more stable than your measurements need to be.
GOOD LUCK ON THAT PART!!!
 

MisterBill2

Joined Jan 23, 2018
6,998
The actual purpose is not really described, and without knowing tht the very best available is blind guesses. The TS could attach them all rigidly to a plate and mechanically shock the plate and measure the actual frequency generated by each crystal. But for what purpose? To signal the aliens orbiting in their cloaked spacecraft? Or to cast a spell to bring in demons from another dimension? Or possibly to assume control of somebodies mind? Without some stated purpose or goal the answers really don't matter.
 

Tonyr1084

Joined Sep 24, 2015
5,039
The circuit must give a sharp pulse to all the crystals at 1Hz.
They are regular 32khz cylinder oscillators used in watches.
32,000 Hertz versus 1 Hertz. Anyone see a problem with the notion of using 32Khz crystals for a 1 second click? There's going to be a need for some circuitry to divide these 32,000 pulses down to a single pulse per second.
WOW , I have to ask , why ?
And so do I. Why? What are you hoping to (dis)prove?
 

DickCappels

Joined Aug 21, 2008
6,584
32768 Hz divided by 2^15 = 1. Very simple hardware if that's what you want to do.

It seems to be a just-for-fun type of project. All work and no play...
 

Ian0

Joined Aug 7, 2020
454
No-one has answered the initial question:
I need the simplest circuit. . .
I suppose it must be the Pierce oscillator which you can make out of a single 74HCU04 gate, two resistors and two capacitors.

When the gate changes state, it will draw more current from the supply and the supply will slightly dip. This may well synchronise other oscillator in the same IC.

But do you really want to build an oscillator, when all you want is to watch the crystals resonate after an impulse?
 
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