# Need help with Crystal Oscillator circuit...

#### 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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#### Deleted member 115935

Joined Dec 31, 1969
0
WOW , I have to ask , why ?

#### fantaasia

Joined Aug 26, 2020
4
just an idea I need to experiment with

#### fantaasia

Joined Aug 26, 2020
4
a little change:

The circuit must vibrate all crystals in their resonant frequency.

#### MrChips

Joined Oct 2, 2009
25,050
If they are in the same circuit they will be synchronized.

#### MrSalts

Joined Apr 2, 2020
852
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
17,616
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?

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#### upand_at_them

Joined May 15, 2010
766
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
10,580
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!!!

#### DickCappels

Joined Aug 21, 2008
8,169
https://en.wikipedia.org/wiki/Injection_locking

There is nothing new about injection locking. You can even do it with crystals if they are close enough together, but the key, as pointed out in the video is injecting a signal from one into the other(s) or between multiple oscillators as with the metronomes to give it that "kick" that helps synchronize them.

#### MisterBill2

Joined Jan 23, 2018
10,580
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
6,624
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?

#### upand_at_them

Joined May 15, 2010
766
I suspect this may be a silly project idea. More information would definitely help.

#### DickCappels

Joined Aug 21, 2008
8,169
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...

#### upand_at_them

Joined May 15, 2010
766
I'm anxious to hear what the "fun" part is.

#### MrSalts

Joined Apr 2, 2020
852
I'm anxious to hear what the "fun" part is.
When something unexpectedly cool happens!
I doubt anyone has actually done it before so, let him try and report back.

#### ci139

Joined Jul 11, 2016
1,696

#### Ian0

Joined Aug 7, 2020
4,146
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?

#### fantaasia

Joined Aug 26, 2020
4
I got my answers, thanks!

#### MrChips

Joined Oct 2, 2009
25,050
I got my answers, thanks!
So, what were the answers and what did you conclude?
The suspense is killing me!