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PC1966: I had another try with Rc = 1kR and Re = 4.7kR, 10kR and 22kR over a range of voltages from 3-15V. Not a twitter at 20MHz. I also tried two other crystals.

Next I will try keeping Re at 4.7kR and reducing Rc but at the moment it is too hot in my shed to do so.
OK, I will see if I have the parts to try it as well.

At one point we had loads of stuff for this sort of experiment but sadly it was thrown out when my last work ended. We saved some stuff "just in case" but space did not permit all of the items I wish we had kept.
 
This is a handy web site for current activity:
However we have seen the odd flash here that did not register on their detectors.
 
Im loughing how everyone is preoccupied: me with the fv reading, marconi with lightning and pc1966 with stuff that doesnt find or have anymore. Hahaha.
 
Regarding the circuit Symmetrischer Oszillator I have included below again. I don't think this is the working circuit - it is an outline schematic of a circuit missing some key detail. I reckon the circuit idea is a classical astable transistor circuit - see second circuit - which has resistance and capacitance to make it oscillate at a frequency close to that of the quartz crystal as in the second image. The purpose of the crystal connected between emitters is to 'force' operation at its frequency. This is what I am going to pursue.

Make a very simple test for me 1652886764266 - EletriciansForums.net

Make a very simple test for me 1652887169009 - EletriciansForums.net
 
I was just going to say, it looks like a circuit from a patent which shows enough to define the principle that is claimed, but not enough to construct a replica directly. I too would be inclined to provide AC feedback and bias in the usual way, and probably make the emitter coupling somewhat tunable.

It seems a very long time ago that I had the opportunity to make with circuits that might not function, to see whether something can be done some particular way. In my work I am so often against time pressure that the solution has to be guaranteed to work first time even it is technically ridiculous or extravagant. I have used a 14-bit 40-pin PIC running at 20MHz as a monostable to generate a 10 second pulse, because it was already built and reprogramming took 2 minutes vs. 5 minutes to make something specific.

If you asked me to test the frequency of a vanilla-flavour crystal now I would reach for the PIC prototyping board again and have an answer in 20 seconds.
 
We know that is a symbol of a BJT NPN but try with 2 N-ch Mosfets.
Also... Im thinking to use different types of npn's. 1 BC548 and another BD139. To induce a instability in the circuit...
Just putting some ideas on the table.
 
A crude simulation attempt, did not work at 20MHz with 2N2222 but OK with BC548, also used low-Q crystal model so faster to build up (along with 1mV kick at t=0)
Make a very simple test for me circuit-xco - EletriciansForums.net

Time-domain for test point in Tr1 collector:
Make a very simple test for me transient-xco - EletriciansForums.net
 
I gave myself 5 minutes to do this, just to prove we can all build a discrete transistor crystal oscillator that doesn't work...
First transistors I came to - ZTX753s - should have enough zing to work. The circuit has a name but I can't remember it, a common-base stage driving an emitter follower. I made the values up as I went along, they won't be far out but it still doesn't work. I've no interest in simulating it or debugging it, time's up!
 

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So then I decided to give myself another 5 minutes to build a crystal oscillator the way I would have done if somebody had said: "Build a simple crystal oscillator." I.e. with an 'HC00. Of course this one works just fine. I didn't bother tuning it, I used the first capacitors that I picked up from the drawer, which turned out to be 22pF. Build time was just under 3 minutes including stripping some wire to make links.
 

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And this is how it looks with a 4MHz xtal.

*BONUS POINTS for anyone who noticed I had the scope's 20MHz bandwidth limiting switched on. The actual output waveform is very ringy because I did a lousy job of decoupling the power supply (stood a ceramic 0.1 across the IC without chopping its leads down). You can change the W/F just by bending this component about. It could be fixed but... time's up!

E2A, I semi-fixed it (relocated the bypass cap and poked the probe direct into the breadboard)
 

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very interesting update.
I managed to split 1/10 of my test PWM original fv. From its 850Hz down to 85Hz
Now Im playing with some capacitors values to bring it down to 1/100.
My target end result will be 1/1000.
And, I did managed to --average-- the 1/100 values. I say average because the fv counter is jumping a couple of Hz up and down. It should be 8.5Hz but is heavily fluctuating with diverse values between 10Hz and 6Hz. So I am theoretically at 8 but because is jumping all around these values, it was hard in the beginning to understand where I stand. But staying and watching these values for a while, a couple of minutes, I concluded it is jumping around these margins. That might be from the High resolution of the splitting, all the circuit(s) combined might present some tolerances, especially the capacitors and resistors and why not the chip(s).
At 1/10, it does not jump at all, it stays put at that fv. So.... I think im good at this point.
I might have to make a second circuit that will split another 1/10 from this one that is 1/100 and in the final output will get 1/1000. And I expect it will be extremely jumpy at that Very High resolution. If it is a way of "average" all these jumping, especially at 1/100 stage I am right now. That will give a good clear chance for the 1/1000 stage. Hmmm. But it is in plan. For now, I have to reach that 1/1000 target and Im GOOD, literally. Haha.
 
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A crude simulation attempt, did not work at 20MHz with 2N2222 but OK with BC548, also used low-Q crystal model so faster to build up (along with 1mV kick at t=0)
View attachment 97652

Time-domain for test point in Tr1 collector:
View attachment 97653
I had another go this morning after thinking about the small signal model of this circuit and why the ratio of Rc to Re matters so much- see first attachment. I tried Rc = 1kR and Re = 4.7kR and even exchanged the BC549s for two new but in my construction it did not oscillate. Not enough feedback methinks so I swapped Rc for 100R and the symmetrischer oszillator found its 20MHz voice. We did it Sir and self starting to boot! 🙂
 

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Not enough feedback methinks so I swapped Rc for 100R and the symmetrischer oszillator found its 20MHz voice. We did it Sir and self starting to boot! 🙂
Excellent!

While the E-E impedance should be roughly -2*Rc quite possibly the higher Rc values along with stray capacitance might cause too much phase shift. I seem to recall that 10-20MHz crystals are below 100R series resistance so indeed 100R values for Rc would be adequate, as you have so well demonstrated!
 
q12x. : My next step is to take the small amplitude 20MHz sine wave and turn it into 20MHz pulse stream of TTL logic 0 and 1s to feed into the divider circuit.
 
Congratulation mister @marconi I am really happy you made it !
But I am not sure I understand completely your values.
So I grabbed all the information you provided so far:
Rc for 100R and the symmetrischer oszillator found its 20MHz voice.
did not work at 20MHz with 2N2222 but OK with BC548
I tried Rc = 1kR and Re = 4.7kR
and I redraw the circuit with the new values:
- Are these the values you used?
Make a very simple test for me -Oscillator Circuit of The First Quartz Wrist Watch(Symmetrischer Oszillator) - Copy - EletriciansForums.net
 
Congratulation mister @marconi I am really happy you made it !
But I am not sure I understand completely your values.
So I grabbed all the information you provided so far:



and I redraw the circuit with the new values:
- Are these the values you used?
View attachment 97682
Yes. VB is 5 Volts not 1.35V. The npn transistors are BC548B types. the letter A, B or C after BC548 indicates the so-called direct current gain of the transistor - the hFE - and relates the emitter-collector current flow to the base-emitter current flow eg: Ice/Ibe. Which BC548s do you have? Cs have higher gain than Bs than As so I used the mid-range gain type.

See top of page 2 of:

BC548B datasheet - https://datasheetspdf.com/pdf-file/1292183/Kingtronics/BC548B/1
 
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Mine are BC548 B - coincidence! like yours.
I have uA741(not that used anymore) and LM358(most used)
Updated circuit after your last specifications:
Ive added + and 5V and gnd symbol. Also B after tr name.
Make a very simple test for me -Oscillator Circuit of The First Quartz Wrist Watch(Symmetrischer Oszillator) - Copy copy - EletriciansForums.net
 

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