Make a very simple test for me

[_q12x_]

Im asking this question to everyone but in particular to my friend here mister @marconi .
I am a professional artist but I am not an electronist like you guys here. That doesnt mean I dont know anything. I know something but I can't raise to some of your standards and knowledge. I'm happy (sometimes fun) to learn something new here and there.
- Recently, it was suggested to me to buy a frequency counter, because I got into some crystal oscillators I have in my stock and they have no markings anymore and the reason is a bit too long story. I already buy a cheap one from ebay, exactly this yellow version (not the red one)

but it is on the road. I have about 2-3 months (usually) to wait, until it arrives.
I also have a dinky DSO138 osciloscope that is trembling of Parkinson all the time. So you can imagine, I can't put my 100% trust in it all the time.

So, my first circuit for testing a crystal oscillator I find is this:
"Oscillator Circuit of The First Quartz Wrist Watch"

I had high hopes for this circuit. I used 10k for both Rc(c=collector) and 1k for both Re(e=emitor). And I used BC548 for both Tr.I used a known value of a Quartz of 20MHz. And I used 2V (VB=Voltage Battery). But the oscilloscope just showed me some very weird and random readings that I can not even put head to tail. I build this circuit on my breadboard, and that may had influence the results.

---So this circuit didn't work for me---. But I bet my as it must be a good one and I blame my DSO138 for being crappy.
And also not having (yet) a frequency counter.
- In short, this is more a curiosity for me. I hope it is for you as well.
- My request for you is to help me with the following:
- Because you are a better electronist, you must have better tools than I have. So, using your normal oscilloscope and your normal frequency counter, (I say normal, comparative to my ebay measuring tools), please make this very quick and simple circuit and measure it for me. And confirm to me with some images or a short video, that everything is working as I imagine and hope. It must be. The idea is to measure 20MHz on the "out" pin in respect to the ground (if you used the same values as I used). That's it. Also, feel free to change the resistors or the transistors. It must be GPT (general purpose transistors), but the resistors I used I just guessed their values. I didnt had the values from the page with the circuit. So I had to invent something. And those values are my best guess.
Thank you and hope to hear good news from you.

 

[marconi]

I think the problem is because you are using silicon transistors which have a higher base emitter conduction voltage (circa 0.7V) than germanium ones (circa 0.2V). The small difference matters when Vcc is only 2V. In the early days germanium was more common than silicon. With a low VB voltage of 2V the transistor BC548 may not be in the required operating zone.

Just to see if the circuit does oscillate replace the 2V battery with say 5V- 6V and tell me what happens and you see on your scope. Also check you have connected the power supply to the circuit correctly so that VB is positive and the ground rail is negative since the transistor is npn type.

 

[pc1966]

Well that oscillator would be for series resonance between the two low-impedance emitter points of the two transistors. However, my immediate reaction to looking at the circuit is there is no attempt to stop DC positive feedback, so it could end up resting with one transistor saturated and the other cut-off. You might need to make the emitter resistors Re larger than the collector resistors Rc to stop that (i.e. so each transistor's DC gain is less than 1) and then rely on the crystal's series impedance being low enough that you have greater than unity AC gain for the oscillations to start.

A typical 20 MHz crystal would have a series resistance of something like 100R or that sort of order, so trying a swap with Rc = 1k and Re = 10k might be happy.

You also need to consider the loading of the scope, etc, on the collector of Tr2 as that will reduce the gain (if AC coupled) and possible impact on DC bias (if DC coupled). You might want to put a capacitor of some 1nF or whatever and a resistor of over 1k in series as a means of tapping off the signal without too much load. Or use a 3rd transistor as an emitter follower buffer (Tr3 collector to supply, Tr3 base to Tr2 collector, Tr3 emitter with 1k to 0V, output from Tr3 emitter via 56R and 1nF in series).

 

[pc1966]

Incidentally you would not believe the number of different crystal oscillator circuits that have been developed over the years!

They span all sorts of different use-cases and part of that comes from the technology for amplification (thermionic valve where one is as much as you want, discrete transistors where over 2 is becoming a crowd, and IC with complexity as cheap), the frequency range needed (so low frequency has high Z crystal so high Z oscillator needed, but very high frequency means forcing resonance on an overtone via frequency-selective amplifier, etc) and the desired purity/stability of the output (typically meaning operating the crystal with a well-defined sine wave drive level and optimising the in-circuit Q factor).

Whole books have been written on the subject, for example:

https://bgaudioclub.org/uploads/docs/Crystal_Oscillator_Circuits_Krieger_Matthys.pdf

 

[Lucien Nunes]

That simple transistor multivibrator was probably running at a much lower frequency and might not be capable of operation at 20MHz due to lack of loop gain. Quartz watch crystals standardised on 32.768kHz very early on, I don't know what the 'first' one would have been but probably no higher in order to minimise dynamic power consumption.

As above there are many different circuits; I would not choose this one. Something like a pair of logic inverters would seem to offer more predictable results.

E2A A little googling suggests that the crystal in the first version of the 35SQ ran at 8.192kHz

 

[_q12x_]

Fantastic explanations ! I love them all.
I will update you with your recommended modifications in a short time.

 

[pc1966]

As I suspected, I actually have that book in hardback:

 

[_q12x_]

I did first @marconi suggestion since it was the simplest to make.
And the same result as before. I test it at 2V, at 5V, at 9V (from my VPSU (Variable power supply unit)) and the same output on all 3 = a flat line. Well, a Parkinson flat line.
Here is the prove:
I did the 2V test anyway, just for the sake of comparison. I do believe your idea with the germanium and silicon diferences. And I know it myself but I didnt think on it. On time. You were faster. Which is good.

The fall:

Do you see what I mean by Parkinson "flat" line? And that my DSO138 is dinky as hell?
You don't believe me. But Im telling and showing you.
You have EXCEPTIONAL osciloscopes compared with my dinki one here.
Anyway...
The rise:

Now at 5V

the fall and rise : (less than 1V)

and finally at 9V

the rise and fall:
notice this is spot on 1V - fix in the middle of the 2V per division square.

and my original circuit:

Im showing here how I connected the osc probes. Green link = poz + and yellow link = neg -.
This is still the original circuit.
Sorry for the blured camera but I dont have my other one at the moment.
I will now build and change the other recomandations !

 

[pc1966]

As pointed out by @Lucien Nunes the original watch circuit would use a low frequency crystal.

These days they are all 2^15 = 32,768 Hz for ease of dividing to 1 Hz for counting seconds, etc, and are quite cheap and available in many places. The original choice might have been less as Lucian's points out in the days before dedicated IC dividers and each step was done by using separate parts.

Low frequency crystals are troublesome beasts, they can be large unless 'tuning fork' style, have a high series resistance and today you would struggle to find anything that is not a mass-market frequency. In the past we got custom crystals from the likes of McKnight Crystals in Southampton, England but that sort of small company has long gone as standard frequencies were all that most need due to frequency synthesisers and related microcontroller control, etc, became cheap and ubiquitous.

Your circuit, assuming ideal transistors, would present a negative resistance of around 2*Rc between the emitters (basically a delta-I current through the crystal products delta-I*Rc voltage on both emitters) so if you get a 32kHz watch crystal such as this:

https://www.newark.com/multicomp/mcrj232000f12300h3h/crystal-32khz-12-5pf-cylinder/dp/56P2811

The data sheet has its resistance as 35k Ohm max, however, you need a bit more than that to reliably start up so probably you would be looking at 100k for the Rc values.

To preserve DC stability you need Re to be greater than Rc, so you might be looking at 330k or similar, also to keep operating current down to prolong battery life and to avoid over-driving the crystal (no spec on data sheet for drive level unfortunately). With such high impedances you would need to make sure you don't load the collector too much to extract the signal, so either a buffer or a 100k resistor + coupling capacitor, etc.

Lucian also mentions about the transistor frequency response, that is important as it limits the frequency at which you can get useful gain and (less obviously) it is also current-dependent in the transistor. Looking up the BC548 data-sheet the fT is nominally 300MHz at 5V and 10mA, but could well be below 10MHz in this circuit, so a high frequency crystal may not work without pushing down R to get I up for the transistor.

@marconi also raised an important point about biasing, but with 2V and approx 0.7V (a little less at low currents) for the B-E junction you should be seeing around 0.1mA or so per transistor with Rc = 1k and Re = 10k (so fT probably around 20MHz, marginal here with 20MHz crystal). Hence if you want to use it at 20MHz you might be better to accept high current and not lithium cell powered and just set the supply to 5V and maybe drop emitter R to 2.2k

 

[_q12x_]

...32,768 Hz ...

Damn. I made a big mistake. For some unexplicable reason I read the "20 000" marking on my OSX (crystal oscillator) as Mega. While it is 20 Kilo. Damn. And I can not EDIT the original post either to correct it... what a shame. Again, Im not working as often as you guys here, with these OSX's. My VERY simple goal here is to measure some Blank OSX's I have scrapped and collected for a long time. Blank = no markings, no letters or numbers on them. Simple. And quite recently I learned that I need a specialized tool for it, the frequency counter. That I am waiting for at the moment to arrive in couple of months. It would be good to be able to measure the fv only with the osciloscope, and I bet it is possible, but I am very sure not with what I have here.
That is a very nice book, by the way !

 

[_q12x_]

Hmmm, I just checked the other known values and I didnt give this much attention to this detail which is very important. Which are the Kilo and which are the Mega. I ASSUMMED "20 000" marking is Mega:
So this is the OSX I used so far in all my tests and circuits:

As you can clearly see it does not have a K or M indicator at the end. Thats why I assumed and now I think probably certainly wrongfully.
Because, I remember the Mega on some of my OSX's and I check it and I find one:
I know is not THAT visible but it is good enough. It says 27.000 MHz.

So a "20 000" without the MHz specified in its end, it might simple be a 20 KiloHz.
Ha.... Right? I am thinking out loud here. Again, I am working with these components almost never. I am not used to them. I am not using them in my circuits that often. All that I used them for was for my PIC MCU external clock signal, and thats this shortcut term I borrowed from as well. Also I didnt used them for PIC's as often as well either. But I thought, to have a bunch of these OSX for some future experiments that never happened.

 

[pc1966]

Damn. I made a big mistake. For some unexplicable reason I read the "20 000" marking on my OSX (crystal oscillator) as Mega. While it is 20 Kilo. Damn. And I can not EDIT the original post either to correct it... what a shame. Again, Im

A 20kHz crystal would be very unusual, especially in that sort of a package. I suspect 20MHz as you initially thought.

not working as often as you guys here, with these OSX's. My VERY simple goal here is to measure some Blank OSX's I have scrapped and collected for a long time. Blank = no markings, no letters or numbers on them. Simple. And quite recently I learned that I need a specialized tool for it, the frequency counter. That I am waiting for at the moment to arrive in couple of months. It would be good to be able to measure the fv only with the osciloscope, and I bet it is possible, but I am very sure not with what I have here.

If you can measure the time between successive edges with the scope then freq = 1 / time

However, most scopes are not very accurate at this, even the ones that have built-in capabilities to estimate frequency. You will get 0.1% or so accuracy often (i.e. 1E-3), not the 1ppm or better sort of thing you get from basic frequency counter (i.e. 1E-6) such as:

Aim-TTi TF930 Frequency Counter, 0.001 Hz Min, 3GHz Max, 10 Digit Resolution | RS

uk.rs-online.com

That is a very nice book, by the way !

It is handy, can't remember when I bought it but I thing a couple of decades ago. This presentation might be of some interest to you:

http://www.leapsecond.com/nawcc2013/tvb-2013-Extreme-Amateur-Timekeeping.ppt.pdf

 

[pc1966]

Looking up your DSO138 oscilloscope it appears to have a 200 kHz bandwidth so you simply will not see a 20MHz signal on it.

If you can get a watch crystal of 32,678Hz and try with higher resistance values to match that sort of crystal (suggested above) then you might see it.

 

[_q12x_]

Looking up your DSO138 oscilloscope it appears to have a 200 kHz bandwidth so you simply will not see a 20MHz signal on it.

If you can get a watch crystal of 32,678Hz and try with higher resistance values to match that sort of crystal (suggested above) then you might see it.

Very good idea and I didnt check it myself or try to learn this little detail about my scope. Very good that you check it for me. Excellent. Yes this make sense. The scope may be very much, very limited. As I anticipated without actually check it like you did. Like I said, very dinky. Haha. Hmmm, that makes a ton of sense. I will TRY to find - if im lucky something under 200kHz in my OSX (OScilator X=value) known values bag.

 

[_q12x_]

I have an Ingeeneerious idea !
Is there a way to SPLIT the fv of a BIGger OSX into a smaller fv? Just to bring it down under 200 kHz? Just enough to measure it with my dinky osc? Ha?

 

[_q12x_]

I did what you told me.

If you can get a watch crystal of 32,678Hz and try with higher resistance values to match that sort of crystal (suggested above) then you might see it.

Everything I USUALLY test, especially in low power electronics, signal or logic, I do it @ 5V from my varPSU. So now I test as well. I tested probably more than half of the OSX's I have, known and unknown values, and nothing showed on my DSO138 osc. I even have 4 of those cylindrical you showed me in your link, and nothing. They are (probably) too fast.

Edited:
- I still didnt managed to make your suggested circuit yet. I am very happy that I understand the limit of my osc now. Very happy. That 200kHz sais it all. It is dinky !!! And no matter what testing circuit I make, not even your suggested one, the osc will give me a finger either way.
So it was a very good step to do, in purchasing that fv counter I did some days ago. Which cost me 10$ by the way , comparative to 400$ from your link. But I WISH I have that 400$ one. This one will be another dinky 10$ ebay tool. Oh well, I dance with what I have, right?

 

[_q12x_]

Check that book of yours, see if you can find a 1/10 or a 1/100 fv splitter circuit in it !!!!
The analog way !

 

[pc1966]

I have an Ingeeneerious idea !
Is there a way to SPLIT the fv of a BIGger OSX into a smaller fv? Just to bring it down under 200 kHz? Just enough to measure it with my dinky osc? Ha?

Yes, there are at least two ways to do that:

• Heterodyne the unknown oscillator with a known one and then look for the sum or (more useful here) difference frequency
• Use a divider chip to get a fraction of the oscillator frequency

In your case the divider option is far cheaper and easier to investigate. Look for the 74HC4060 as it will run 20MHz at 5V, is cheap, has a gate that makes for an easy oscillator circuit (or even as an input buffer/amplifier to take the signal from our transistor set-up) and offers divide ratios of 2^4 to 2^14 (with a one gap). So 20MHz comes out of the final stage as 1220Hz.

 

[pc1966]

This data sheet as an example parallel resonance crystal oscillator in Fig 13:

https://www.farnell.com/datasheets/2030232.pdf

For 20MHz or similar then R2 = 2.2k is reasonable. For 32kHz crystal then make R2 = 100k to 220k. Rbias should be 1M usually, but for 32kHz there is some advantage of using 10M (or 1M + 1M with small 1nF capacitor to ground from junction between them).

 

[_q12x_]

Look for the 74HC4060 ...

Well, is not practical. Your IC idea is good but is too late.
Because if I will buy this particular chip now, my fv counter will have been arrived until this chip arrives. What I mean, is there a common way, a circuit way, a easy-er way, a quick and dirty way, a rough approximation way? I really dont need the decimals after the dot. Just the big number and its good enough. So, can you find or think on a circuit from basic components or very common chips like 555 or opamps, that will successfully divide a fv ? This is what I mean. Also use that interesting book for this specific task.

 

[_q12x_]

Hey, thank you all for the commitment and for debugging this problem with me.
You really helped me, especially by figuring out the 200kHz limitation of the osc.
Thank you very much !

 

[_q12x_]

Following your suggestion, using a dedicated chip..... I get involved into research and I find this:

Frequency divider - Wikipedia

en.wikipedia.org

And....I have a bright idea...
After reading about this process, I understand that division by 2 is done using a D flip-flop circuit.

I understand it is a digital logic operation.
And the bright idea is to actually build a D flip-flop circuit. Or use a chip that may already have some ready flip-flop pins.
I have a small list of personal chips I can put down for you to look over, and if you spot any IC that will fit this task, then poke me. I already seen one CD4013 x1 dual D flip-flop but I have only 1 of it.
See if you find others.
Until then, I will concentrate on reading how to make a D flip-flop from discrete components. And possibly make a circuit. Mmmmm....

 

[_q12x_]

Hmmm... I find Frequency divider using 555 timer !!!

Simple frequency divider

Electronic circuits, projects and tutorials. PCB details, microcontroller projects, power supply, high frequency and audio circuits.

www.circuitlib.com

 

[marconi]

q12x : Good evening. I have been occupied today to be of any help(?) but can see that some very able folk have responded.

What is your project goal now please? You have bought a frequency counter which arrives soon. You have some quartz crystals which you want to confirm work and their resonant frequencies. Thus, it seems to me you still need a test rig to put these crystals into to make them oscillate. And you need a way of connecting the test rig to the frequency counter to measure their resonant frequencies. I am happy to help but need some clarification on what next - the test rig?

But before all that - what do you intend to do with these crystals?

 

[7029 dave]

The finest profs on the EF
Just saying hello thats about my input.
Way over my little ole head just a mere installation electrician.
I will be the first to stand on one side of the corner.

 

[pc1966]

And the bright idea is to actually build a D flip-flop circuit. Or use a chip that may already have some ready flip-flop pins.

You can build them, but it is quite a few parts for a single stage and given the expected crystal frequency of 20MHz and your scope's limit of 200kHz, to see something approaching a square wave you need to show at least the 3rd harmonic, and ideally 5th, so you would want a final frequency of around 200kHz/5 = 40kHz.

So your divider would be 20MHz / 40kHz = 500 and closest binary option is 512 = 2^9 = 9 flip-flop stages.

I have a small list of personal chips I can put down for you to look over, and if you spot any IC that will fit this task, then poke me. I already seen one CD4013 x1 dual D flip-flop but I have only 1 of it.
See if you find others.

Most of your ICs are of the CD4000 series, they are only able to clock in to a MHz or so. You need to look at the 74HC series (or 74LS) to get 20MHz or more capabilities. Generally 74HC is easy to work with, some others are not so easy (restricted voltage range, or very fast switching so issues on breadboard use, etc)

The 74HC4060 is cheap, if getting one then buy at least 2 and check it is the DIP version, not surface mount package. It is finding a place that won't charge you a stupid amount of postage that is a challenge!

 

[pc1966]

Hmmm... I find Frequency divider using 555 timer !!!

Simple frequency divider

Electronic circuits, projects and tutorials. PCB details, microcontroller projects, power supply, high frequency and audio circuits.

www.circuitlib.com

That sort of a circuit only works well for a limited frequency range. A typical digital divider works from "DC" (clock stopped) up to the clock limit of the IC (tens of MHz input for the 74HC family).

 

[pc1966]

Way over my little ole head just a mere installation electrician.

Don't put yourself down, you contribute a lot on other matters!

 

[_q12x_]

q12x : Good evening. I have been occupied today to be of any help(?) but can see that some very able folk have responded.

What is your project goal now please? You have bought a frequency counter which arrives soon. You have some quartz crystals which you want to confirm work and their resonant frequencies. Thus, it seems to me you still need a test rig to put these crystals into to make them oscillate. And you need a way of connecting the test rig to the frequency counter to measure their resonant frequencies. I am happy to help but need some clarification on what next - the test rig?

But before all that - what do you intend to do with these crystals?

Hello my friend and salutations from Romania. I believe you speak in name of everyone and some clarification might be in order from my part. Indeed my frequency counter is on the road. That is plan B that is going to happen. But until it arrives, in 2-3 months, I think I can PUSH this thing a little bit. You know? That's my goal here. And by pushing, I mean to make something that works, even if I have to make it from different parts or even circuits. For example, a circuit made from discrete components that will make a single D Flip-Flop stage in the 10 stages that I calculated.
Here is my plan:

20000000 = 20M
2000000 = 2M
200000 = 200k
20000 = 20k =/1000

2^1 = 2
2^2 = 4
2^3 = 8
2^4 = 16
2^5 = 32
2^6 = 64
2^7 = 128
2^8 = 256
2^9 = 512
2^10 = 1024 =10 flipflops

20k or20000 means 20000000/1000 and 1000means 1024 in binary so 10 flipflops
Why 20k? because I think I have larger than 20M, I think Ive seen one at 50M.
Somewhat being in the safe side, and also easy to calculate if you roughly multiply by simply 1000 in your head.

I really don't think the "test rig" as you put it, is the biggest problem anymore. I think the "splitting" as I call it, is the bigger issue. Because as we discovered, my DSO138 is limited to 200kHz so we need to bring everything down to it's level of measuring. That's it. Simple.
And for this, I'll have to use what I have on my hands. Some chips if im lucky or the obvious way, build a couple of discrete D- flip-flops. I'll make a factory of production these days here in my room. Haha. You probably remember how I build my circuits, using cardboard and pieces of bended sheet metal that makes pads for soldering. Very shi..ty ones but good enough for the amount of experimentation I am doing.
What you are wondering so hard now, is why do I want so bad to PUSH it, instead of waiting for my new fv counter? Well, because why not.
If you are good enough to get involved into my small project here, because this will be hard to make anyway. Is to find for me a very good D flip-flop discrete circuit that I can build using my components I have in storage. Ideally is to build it from 555's because I have 100 both DIP8 and smd SOT-23. I am researching myself this possibility at the moment.
I hope is clear enough. If more clarifications needed, just ask me.
- Saying hello back to mister @7029 dave

....
Most of your ICs are of the CD4000 series, they are only able to clock in to a MHz or so. You need to look at the 74HC series (or 74LS) to get 20MHz or more capabilities. Generally 74HC is easy to work with, some others are not so easy (restricted voltage range, or very fast switching so issues on breadboard use, etc)

The 74HC4060 is cheap, if getting one then buy at least 2 and check it is the DIP version, not surface mount package. It is finding a place that won't charge you a stupid amount of postage that is a challenge!

Yes... I am new to this chips you are speaking here. I will start looking for them and probably even buy, if they are not expensive for 100pcs as I usually buy all my components. It is good that you tell me about them. Thank you.
But remember, I will start with whatever I have in hand at the moment.
I believe you are trying to tell me it will not work using discrete D flip-flops or the 555 version of it, because they will not be fast enough for the 20M (or more) speed. If this is the case, please be clear with me now, before I start doing anything ((stupid)ly hard and slow). Its a ton of work but in a few days I think I can do it.
Have a good night (to everyone) and see you tomorrow.
Thanks so far !

 

[marconi]

q12: Good morning. Thank you for your nice email. Gathering dust in my shed I have some 74LS273 octal D type flip flop ics.

https://www.ti.com/lit/ds/symlink/sn54ls273-sp.pdf?ts=1652639946774&ref_url=https%3A%2F%2Fwww.google.com%2F

I will post you some as a gift. Please private message me your address or somewhere to post them to from where you can collect them.

Each chip will divide by 2exp8.

https://www.electronics-tutorials.ws/counter/count_1.html

I will include some 74LS14 Schmitt triggered inverters chips so that you can input the 20 MHz sine wave and output from it a square wave to clock the 74LS273.

https://www.ti.com/lit/ds/symlink/sn74ls14.pdf?ts=1599590379543

You could use a circuit like this using two Schmitt triggered inverter gates as your test rig for the crystals which would in turn output square pulse to drive the frequency divider:

https://electronics.stackexchange.c...nverters-in-quartz-crystal-oscillator-circuit

I see that a later circuit uses 74HCU04 inverters. I will see if I have any. I know I have some 74LS04 ones.

https://www.infinite-electronic.kr/datasheet/54-74HCU04D.pdf

http://web.mit.edu/6.111/www/f2017/handouts/labs/74LS04.pdf



Regards

Marconi

 

[pc1966]

q12: Good morning. Thank you for your nice email. Gathering dust in my shed I have some 74LS273 octal D type flip flop ics.

https://www.ti.com/lit/ds/symlink/sn54ls273-sp.pdf?ts=1652639946774&ref_url=https%3A%2F%2Fwww.google.com%2F

Those are usually intended as bus registers and not so easy to turn in to dividers, though they are fast enough. However, you can covert them in to ring counters with the addition of an inverter:

Ring counters (Johnson Ring Counter)

Ring counters and John counters are special type of counters made of shift registers are being explained here in this article.

www.electronicshub.org

Those examples rely on a not-Q output that is inverted, but a 74LS04 or 74LS14 stage would allow the shift-register-feedback loop to be implemented.

I will post you some as a gift. Please private message me your address or somewhere to post them to from where you can collect them.

That is a kind offer of help

Each chip will divide by 2exp8.

https://www.electronics-tutorials.ws/counter/count_1.html

I will include some 74LS14 Schmitt triggered inverters chips so that you can input the 20 MHz sine wave and output from it a square wave to clock the 74LS273.

https://www.ti.com/lit/ds/symlink/sn74ls14.pdf?ts=1599590379543

You could use a circuit like this using two Schmitt triggered inverter gates as your test rig for the crystals which would in turn output square pulse to drive the frequency divider:

https://electronics.stackexchange.c...nverters-in-quartz-crystal-oscillator-circuit

I see that a later circuit uses 74HCU04 inverters. I will see if I have any. I know I have some 74LS04 ones.

https://www.infinite-electronic.kr/datasheet/54-74HCU04D.pdf

http://web.mit.edu/6.111/www/f2017/handouts/labs/74LS04.pdf

The LS versions are OK with high frequency crystals with low impedance but are far harder to make work reliably than the CMOS types. You generally can't use the single-inverter mode for parallel resonance as you need quite a low feedback resistor to pull the LS style of device in to its linear amplification region, so typically they are best used in series resonance using two inverters.

See page 164 of the linked book for circuit 11.3(a) as an example of forcing TTL in to dirty analogue activities.

Generally the LS14 and similar Schmitt triggers don't make good crystal oscillators as they never go "linear" but are great for cleaning up circuit outputs to get good square waves to reliably clock flip-flops.

 

[pc1966]

If all you have ar LS14 then using a single transistor (or the original two-transistor example) as oscillator and the inverter for clean-up is worth a go.

 

[pc1966]

I believe you are trying to tell me it will not work using discrete D flip-flops or the 555 version of it, because they will not be fast enough for the 20M (or more) speed. If this is the case, please be clear with me now, before I start doing anything ((stupid)ly hard and slow).

Typically the data sheets only show the 555 going up to 100kHz operation. They were typically seen doing audio and below speeds, with newer variants having additional dividers inside to allow very long time constants without crazy sized capacitors.

 

[marconi]

-q12- Good spot by pc1996. I may have a pile of jk flip flops and 8 bit shift registers instead of 273s but we can make 273s do the division. I have ordered some 20MHz crystals to work in parallel with you.

 

[_q12x_]

To mister @marconi
Thank you for your very nice and unexpected gift. I really-really appreciate it and is more than welcomed. I really like that you jumped into my crazy project. Its not an easy project and is very new to me with new challenges. That's why I am PUSHING it before the fv counter arrives. Its more like an experiment or an exercise. Hopefully everything will fit before the fv counter arrives and confirm the findings from this experiment, if successful. We'll see.
I will still PUSH with all I have, until your package arrives, and when is here, I will use your chips to simplify the entire experiment. At least this is the plan.
If your components (the 20Mhz OSX) will come faster than me doing my thing here, please do the entire Splitting circuit. Its a bit of a race with time what Im doing here. No matter from what corner of the world the results will come, the important thing is to get the results. So if you are faster than me in getting this thing working, please do it, because I am equally curious. If you can do it today, do it today, it will be awesome.
Thank you again !

 

[_q12x_]

Im looking on the 74HC4060 datasheet right now.
And from the look of it, it appears it has all these D Flip-flops linked , so pretty much for each advancing output pin, Ill get a greater signal splitting (in my case lower and lower frequency). It is very customizable. Is my observation correct? If it is, then this is a very nice chip !

And... I took a good deal of 3.77$ for 10pcs for SN74HC4060N.
Is always better to have more than less.
So mister @marconi if you happen to read this in time, you can option to not send me your D flip-flops chips. But if you do, is as much very welcomed as before.

 

[marconi]

I do not have any 74HC4060 to send you. I have a selection of other logic ics though which you may find useful. I have kept them all 74 series.

 

[_q12x_]

I do not have any 74HC4060 to send you. I have a selection of other logic ics though which you may find useful. I have kept them all 74 series.

No. What I'm saying is that I already bought 10pcs of 74HC4060 because like mister PC1966 said, they run at a bigger frequency and probably are newer IC's.
So if you want, you can or you can not - send me your IC's that are containing D-flip Flop inside them. You have 74LS273 octal D type flip flop. So now you have the option to send or not to send them. I will like them as well, so for me is still a good batch of IC's even if I will get these other ones. Like I said to you in particular, I have a grand list of IC's waiting for a long time. So every chip have its own characteristics that is always good to have a bit from everything. So im not saying no.

 

[_q12x_]

Could you give me some idea of what you will constructing next?

Yes, I have a line of engagement
1- In the immediate days, until all these packages arrive, I am very concentrated on how to make a D flip-flop from discrete components. And I would like very much you to help me in this little endeavor.
2- Then, I will try the 555 circuits for splitting the fv. See how those will do. Im planning something very simple to test, a very basic oscillation in a couple of Hz, like 10Hz or something, by rotating a wheel in front of a LDR or something fast to make. Or even another oscilator using the 555 again. I dont know. Then, after reading and being sure the real fv of the test device, I will try to read it through the 555 splitter circuit (splitter is faster to write than D flip-flop).
3-Next, if I get good results, I will try to make a couple of 'splitting' modules. Either from discrete or from 555's. All, hopefully until everything arrives.
4- after the IC's arrive, I will make some splitters with these IC's. I presume I will not be even close with my discrete components way, to finish anything important. But who knows, if I work hard enough.... we'll see.
5- in the very end when the fv counter will finally arrive, is check mate. I can test every OSX, put a label on them and mission accomplished. And the project is done.
Again this is more as an experiment or a test. Nothing really to remain in time. Well, only if I will make a video about it, if I make some important progress with all of this.

 

[marconi]

Here is my circuit to test the 20MHz crystals I bought. You can see the waveform and its frequency on my scope. I will draw out the single transistor circuit which uses an npn BC549.

The lower trace shows frequency in 25MHz horizontal divisions. You can see there is a second peak of lower amplitude at 40MHz to the right of the main peak which means the circuit is oscillating at two frequencies. The scope shows the waveform of these oscillations when they are added together.

 

[_q12x_]

A very small update:
This one is a variable PWM using a 555.
(The 555 Im using is a SOT23 smd fix in the middle, that black square)

But this is a second circuit. A clone if you like.
Because I build another one a couple of weeks ago and install it and run it for a device I make but is on hold at the moment for some other components to arrive for its upgrade.
I hope is clear enough...I tend to give too many details...

This is the exact same circuit that I am making from scratch (again) but the difference is it will be a portable and testing circuit, and not a fixed one as in the example.
I dont really have to make it but it was in plan so I will make it these days. I started it last night and now its pads are finished.

Ive also thought on other 2 sources of test oscilators.
An astable flip flop that I already have in stock for a long time, made from smd components. Very cute and small and I almost completely forget it.
And a voltage divider hooked up to mains for a nice 50Hz input oscillations with 1:100 ratio. Nice eh?
So in total I will have 3 [test] sources of oscilations.
Why? because I mentioned, I will have to test the D Flip-Flops I will make. Thats why. Aaaaah, right?
Stay tuned.

 

[_q12x_]

Here is my circuit to test the 20MHz crystals I bought. You can see the waveform and its frequency on my scope. I will draw out the single transistor circuit which uses an npn BC549.

The lower trace shows frequency in 25MHz horizontal divisions. You can see there is a second peak at 40MHz to the right of the main peak which means the circuit is oscillating at the two frequencies of the crystal which explains the distorted sine wave.

Oooh, very nice and I totally can see the 20Mhz in the display counter of the osciloscope.

VERY NICE TOOL you have there. VERY NICE ! Aaah.
Yes, put the circuit here.
I really wish you could test my original quartz circuit in the original post on the top. Just to have peace of mind that circuit is good and running. I really love that circuit, how simple and efficient it looks.
Thank you mister @marconi for making these tests with me ! Really great and is a pleasure to see such fine equipment you have there, oooh.

 

[_q12x_]

Do you see that under 1mm distance between pin 7 and pin 8?
Made on cardboard and handmade cut and bent all the solder tabs !!!
Cool, yes?

 

[marconi]

I will have a go at constructing this circuit tomorrow.

 

[marconi]

The circuit for the 20MHz oscillator. It is similar in design to a Colpitts Oscillator circuit. See:

https://www.electronics-tutorials.ws/oscillator/crystal.html

Colpitts was an American engineer:

Edwin H. Colpitts - Wikipedia - https://en.wikipedia.org/wiki/Edwin_H._Colpitts

 

[_q12x_]

yes, I definetly like your circuit more now, because is way more simple than mine.
Very good !
I managed to solder every component now on that board. But I have to add copper wire links between the pads and it is done. Today I will finish it. Oh boy, you have no idea how intense and hard is to do it like I do. But I get results so, I say is worth the effort.

 

[marconi]

A very small update:
This one is a variable PWM using a 555.
(The 555 Im using is a SOT23 smd fix in the middle, that black square)
View attachment 97596
But this is a second circuit. A clone if you like.
Because I build another one a couple of weeks ago and install it and run it for a device I make but is on hold at the moment for some other components to arrive for its upgrade.
I hope is clear enough...I tend to give too many details...
View attachment 97599
This is the exact same circuit that I am making from scratch (again) but the difference is it will be a portable and testing circuit, and not a fixed one as in the example.
I dont really have to make it but it was in plan so I will make it these days. I started it last night and now its pads are finished.

Ive also thought on other 2 sources of test oscilators.
An astable flip flop that I already have in stock for a long time, made from smd components. Very cute and small and I almost completely forget it.
And a voltage divider hooked up to mains for a nice 50Hz input oscillations with 1:100 ratio. Nice eh?
So in total I will have 3 [test] sources of oscilations.
Why? because I mentioned, I will have to test the D Flip-Flops I will make. Thats why. Aaaaah, right?
Stay tuned.

So that I can sleep tonight without the worry - please tell me this 50Hz signal is from the secondary side of a low voltage eg less than 25V double insulated safety transformer.

 

[marconi]

So that I can sleep tonight without the worry - please tell me this 50Hz signal is from the secondary side of a low voltage eg less than 25V double insulated safety transformer.

q12x : It is not wise and I have always assumed you are wise - to be directly (galvanically) connected to the mains or other unsafe to touch voltages. You know from what you have taught yourself that it is easy to construct a perfectly safe circuit which provides a low level 50Hz signal derived from the oscillations of the mains which is galvanically isolated from the mains. In my workshop, because I work alone for long periods, I only do projects operating at up to 20V dc. There is enough amusement for me in doing these low voltage safe projects which do not risk my life and making my wife a widow. I strongly recommend this same approach to you.

 

[_q12x_]

Dont worry man, its fine.

 

[_q12x_]

Huuuuiuuuuiuiui it was hard and intense.
But I finish it. Its a PWM using a 555 (SOT23) driving a mosfet (A09T) that can drive a small DC motor like a computer fan at 12V. Already test it and is working like a dream.
So now I have something to oscillate for further testings.

This circuit is from internet but the blue inscriptions are mine. Also the blue circuit I design it. Is not much but is doing what I want. (Is looking so much simpler in the circuit schematic, right?)

Next, is to research and find a way to make a D Flip-flop from discrete components.
This is contra-time until mister @marconi IC's package arrives in a week he said... but not the european postage is the problem, but my romanian postage is slowing EVERYTHING down, because they have the power and they know it. We'll see. It would be nice to have it in 7days.
So I must hurry more now, haha.
Im so tired but very happy this circuit now is alive. I worked all day at it. Probably 9h straight.
I will update here what D Flip-flop from discrete components I will find. And tomorrow I MUST build the first one ! That's the plan.