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Re: The Jeffree Cell

PostPosted: Tue Mar 05, 2019 3:49 pm
by Harry Dalek
On the newer Ultrasonic piezo Transducer idea i found they can be got up to 3MHZ
https://applevista.en.alibaba.com/produ ... _28mm.html
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Great information in old magazines,every little be helps
Radio-News-1926-01-R.pdf
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From the magazine above..interesting to see the size of a 1926 crystal and its holder types.
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Re: The Jeffree Cell

PostPosted: Tue Mar 05, 2019 7:00 pm
by Klaas Robers
If you look at the holders, in most of them the crystal is mechanically held flat. That implies that the crystal cannot vibrate in thickness or bending mode. That is understandable, because in that mode the crystal is giving sound, that is it emits power to the air. That decreases the resonance sharpness, which is the only task of a crystal for frequency control of a transmitter or receiver. So crystals made for that aim will not give sound into a liquid or a solid (glass).

So the crystals that you opened are not usefull for making ultrasonic sound in water / oil. Then the ceramic transducer is a better thing. Those transducers are used as under water microphones for sonar. They emit sound and receive it again.

Re: The Jeffree Cell

PostPosted: Wed Mar 06, 2019 9:04 pm
by Harry Dalek
Klaas Robers wrote:If you look at the holders, in most of them the crystal is mechanically held flat. That implies that the crystal cannot vibrate in thickness or bending mode. That is understandable, because in that mode the crystal is giving sound, that is it emits power to the air. That decreases the resonance sharpness, which is the only task of a crystal for frequency control of a transmitter or receiver. So crystals made for that aim will not give sound into a liquid or a solid (glass).

So the crystals that you opened are not usefull for making ultrasonic sound in water / oil. Then the ceramic transducer is a better thing. Those transducers are used as under water microphones for sonar. They emit sound and receive it again.


Yes Klaas you picked up some thing i didn't notice about vintage crystals they are held in place flat some thing different really to the modern crystals which can vibrate held either end by thin rods ,perhaps the size and the thickness is larger for an old crystal .....Still the jeffree cell was made with some thing like this with an x cut crystal ....how they did it is amazing ....I will have a look at the world war 2 crystals when they come and take notice of the construction of the holder contacts ...i think the crystal would be either a y or x cut type .
I am thinking the same on the newer ceramic idea that its is an easier and and more efficient way of doing it ...a Lot less voltage needed as well for the oscillator ...frequency its a bit lower ,i have seen they will make to order frequency wise and mentioned and one selling site 5 MHZ or what ever but that i am sure costs ! i will experiment with the 1.7 mhz and see nice to make cell and get away from liquid every where and do some light experiments .

Re: The Jeffree Cell

PostPosted: Fri Mar 08, 2019 1:13 am
by Klaas Robers
The modern high frequency crystals vibrate in a "shift-mode". That is, if you lay the crystal flat on the table, that the top plane and the bottom plane move left-right-left with respect to each other. This gives only visible and feelable movement at the very thin left and right edges. The larger old crystals have much lower resonance frequencies, because the frequency is directly coupled to the dimensions of the crystal.

At resonance there is an accoustic movement / standing wave in the crystal. In most cases the length / thickness is 1/2 wavelength of the accoustic wave in the crystal. Accoustic waves travel in crystal, but also in glass, with a speed of about 5 km/sec. So a crystal of 10 MHz carries a accoustic wave with a wave length of 10 000 (m/sec)/ 10 000 000 (MHz) = 1/1000 meter. You will see that the crystal has a thichness of 1/2 mm, i.e. the size of a half wavelenght. If you have a micrometer, measure the thickness of your 4,4 MHz crystal.! Then you can calculate the exact speed of sound in the quartz.

Low frequency crystals are large. A 100 kHz crystal has (in this case) a length of 5 cm. Yes, it is as simple as that.

Re: The Jeffree Cell

PostPosted: Fri Mar 08, 2019 1:09 pm
by Harry Dalek
Klaas Robers wrote:The modern high frequency crystals vibrate in a "shift-mode". That is, if you lay the crystal flat on the table, that the top plane and the bottom plane move left-right-left with respect to each other. This gives only visible and feelable movement at the very thin left and right edges. The larger old crystals have much lower resonance frequencies, because the frequency is directly coupled to the dimensions of the crystal.


Hi Klaas thanks for the Informative reply that does make sense from what i have noticed very much so on the 2 mhz crystal where the liquid tends to gravitate to one of the edges .
At resonance there is an accoustic movement / standing wave in the crystal. In most cases the length / thickness is 1/2 wavelength of the accoustic wave in the crystal. Accoustic waves travel in crystal, but also in glass, with a speed of about 5 km/sec. So a crystal of 10 MHz carries a accoustic wave with a wave length of 10 000 (m/sec)/ 10 000 000 (MHz) = 1/1000 meter. You will see that the crystal has a thichness of 1/2 mm, i.e. the size of a half wavelenght. If you have a micrometer, measure the thickness of your 4.4 MHz crystal.! Then you can calculate the exact speed of sound in the quartz.


So there is a time delay via the crystal and also a speed delay depending on what liquid is used (density) if we are talking of it in the form of a jeffree cell very much a delay line happening , i don't have any thing to test the thickness of a crystal no way on a newer one , the larger ones coming perhaps .

Low frequency crystals are large. A 100 kHz crystal has (in this case) a length of 5 cm. Yes, it is as simple as that.


I think crystals of the same frequency a large older one and a newer small case type thickness would follow the large would still be thicker ..higher the frequency thinner the crystal the lower thicker it would be `,i am interested to see how thick the 8 mhz one's coming are ..will show them when they turn up .

Re: The Jeffree Cell

PostPosted: Fri Mar 08, 2019 11:07 pm
by Klaas Robers
If the sound wave runs in the thickness of the crystal, the size doesn't matter. A 4 MHz crystal had always the same thickness, if the speed of sound is the same in both crystals. For quartz that will be the case I believe.

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I made a small drawing if the vibrating crystal. As far as I remember, this is the AT-cut. The red and the blue lines indicate both shapes. The arrows show the directions of movement of the upper and the lower surface. You might see that all the action is in the horizontal direction and there is hardly any activity in the vertical direction.

This implies too that if you make the crystal wider, nothing changes. Then the thickness is the "mean" thickness. Now that we can make crystals more precize, we can also make them smaller.

Re: The Jeffree Cell

PostPosted: Sat Mar 09, 2019 9:40 pm
by Harry Dalek
Klaas Robers wrote:If the sound wave runs in the thickness of the crystal, the size doesn't matter. A 4 MHz crystal had always the same thickness, if the speed of sound is the same in both crystals. For quartz that will be the case I believe.


On the small crystals there is a thickness difference i can just notice but i can see very much so on the size and the thin plate electrical connection size is large on low frequency crystals and small on high frequency crystals .
Old crystals the electrical connections are over the full area of the crystal i wonder why now there's a difference


I made a small drawing if the vibrating crystal. As far as I remember, this is the AT-cut. The red and the blue lines indicate both shapes. The arrows show the directions of movement of the upper and the lower surface. You might see that all the action is in the horizontal direction and there is hardly any activity in the vertical direction.


On the crystals cut ....your drawing of the direction of vibration on a At cut reminds me here of the 2 Mhz crystal in video instead of directing the oscillations to a circle point center of the crystal as i see in my past experiments (they must be an x cut )it forces the liquid to the outer edges so another cut AT cut sounds right from your description
water used here



This implies too that if you make the crystal wider, nothing changes. Then the thickness is the "mean" thickness. Now that we can make crystals more precize, we can also make them smaller.


So you would think a crystal of today and a crystal of the past the size is not that important but thickness is of cause for frequency ...at first i thought that the thickness of say a 4 mhz one would have to be the same as one in the past but just larger ...i can only speculate here and look at old pictures till i get my hands on one.

Re: The Jeffree Cell

PostPosted: Sat Mar 09, 2019 9:54 pm
by Harry Dalek
Now i don't know what to make of this on Quartz crystals ! new to me ,i would of thought we would have flying saucers by now if this were true ... :shock:

Re: The Jeffree Cell

PostPosted: Sun Mar 10, 2019 2:41 pm
by Andrew Davie
Harry Dalek wrote:Now i don't know what to make of this on Quartz crystals ! new to me ,i would of thought we would have flying saucers by now if this were true ... :shock:


You're all setup to perform that experiment, aren't you? A decent pair of digital scales would be cheap.
I'd be very curious to see if you can nullify gravity, Harry!

Re: The Jeffree Cell

PostPosted: Sun Mar 10, 2019 6:39 pm
by Harry Dalek
Andrew Davie wrote:
You're all setup to perform that experiment, aren't you? A decent pair of digital scales would be cheap.
I'd be very curious to see if you can nullify gravity, Harry!


Narrr not this one Andrew hard enough to get the buggers to vibrate

Not only does it nullify Gravity to the point where its anti gravity really and it increase's in mass from voltage or at least from its original size ...now this is interesting more how it got in the magazine ....i take it this bit of science fake never went any where a good thing too just in time for Hitler to use it in the next few years ...or may be those Nazi ufos were real with high voltage Quartz drives :wink:

Re: The Jeffree Cell

PostPosted: Sun Mar 10, 2019 8:10 pm
by Harry Dalek
The original idea here is just seeing how far this can go with the Quartz but i do think it would be much easier with PZT piezoelectric ceramic to make a Jeffree cell ...
The PZT piezoelectric ceramic is very interesting i have an idea or 2 i want to try out with them
Back on the Quartz and the Quartz Jeffree cell oscillator i noticed if you tap the crystal you can Am modulate the carrier the effect is more to the center of the crystal ,i think if you made a paper cone you might be able to modulate your voice or sound sort of turning it into a mic just a little silly experiment ..transmitter on the SW band ...it has an AM modulation via the second Triode any way for what it was made for but shows mechanical effect on the crystal does also work in reverse as in response to applied mechanical stress.
Any one else that makes the Triode Harley oscillator modulator make sure all Caps are High voltage , I had trouble of late with a Trimmer cap to the oscillator control grid i replace the fixed cap 20pf i think it was with a variable one the dielectric failed on the trimmer after a while and causing the oscillator to play up ..... i used a air gap version you might noticed in one of the videos posted a day back or so back to working fine again .

Re: The Jeffree Cell

PostPosted: Mon Mar 18, 2019 3:30 pm
by Harry Dalek
Have been waiting for my ebay goodies to turn up and the first lot has ,which are now mine the world war 2 8 Mhz Quartz crystals ...boy the cases are big hate to think of the size of the gear they came out of no attempt at Miniaturisation i bet .
I am interested to see the crystal its self ,looking at the bakelite plastic the holes where i think the case is screwed together has what looks like a dry putty filling the holes ...I will show the crystal once i get one open but out of interest i would like to test them as is if they still work after all these years .
I need to convert the Valve Hartley oscillator to a higher frequency top it will do with the current coil is 6 mhz,so not useful for tests yet with these .
Shown all 3 1945 crystals .

Re: The Jeffree Cell

PostPosted: Fri Mar 22, 2019 5:37 pm
by Harry Dalek
The 1.7 Mhz PZT piezoelectric ceramic disks arrived and i have been experimenting with them ,mainly with a little driver board that came with one .
So i had a go at knocking together a copy of the Radio and Hobbies December 1952 cell.
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And here's what my copy made out like of an empty plastic solder holder tube from jaycar .
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i drilled one side out so i could hot glue the piezo disk to it need to really keep the connections dry on the back side ,the lid has cork stopper glued to the inside
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At first i could get the board to work the piezo disk perhaps to much pressure over filling the tube ,emptied it a bit and back to work kept filling again so it was more that .
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Rather strong effect turning the liquid to a vapor and it is pretty much vibrating the water giving the same effect and temperature as boiling water in a pot on a stove ! A jeffree cell i would think does not need this much effect on the liquid but temperature is a problem as i found out in the oil experiment :roll:

Re: The Jeffree Cell

PostPosted: Fri Mar 22, 2019 6:25 pm
by Harry Dalek
The tests were mainly to see if the tube would hold the liquids and the ultra sonic PZT piezoelectric ceramic worked .
I found water being denser was harder to vibrate with the amount of water on top of the ceramic disk in the length of that tube ...
Went with something less dense olive oil ,it will take the tube being full but vibrating the oil at 1.7 MHZ it too slowly gets hot so hot it melted the hot glue and there went the plastic tube idea as you see in the last video !




Re: The Jeffree Cell

PostPosted: Fri Mar 22, 2019 6:43 pm
by Harry Dalek
Back onto the 8 Mhz WW2 Quartz crystals i tested all 3 of the crystals today and all 3 worked i can check them via the scope and a few stages of 7490's dividing the frequency down to a pulse i can view,my frequency meter only go's to a few Mhz ...
I am yet to open one up ....
I still have to convert the valve oscillator to 8 Mhz but am keen to see the size of the Crystal might have a look at one over the weekend .