BSR Factory Workers: reaching out..

[_Cosmic_]

Here's my next set of experiments.
I constructed a method of containing the crystal elements in each axis x,y and z. I used 2 conductive plates soldered to wires that were wound around the plus and return of a 3.5mm jack leading to the mic input of the PC. Blue tac was used to anchor the crystal in place and to maintain pressure on the contact points between the crystal and the metal plates.

I used a digital oscilloscope that was downloaded to my PC.

Experiment 1.
Crystal size: 1cm x 0.9cm x 0.3cm. Almost a flat square.

Probes on each of the Y axis:
Tapping on flat topside produced 780mV

Probes on each of the x axis (top and bottom flat sides):
When pressed on or handled 150mV-190mV was produced.
I have a record of 600mV in the results but from unknown source.

Probes on each of the Z axis (end to end):
Taps all round produced peaks of less than 20 mV.
Squeezing on one side of the z axis produced peaks of 90mV

According to the digital scope the prominent frequency was 50Hz

Experiment 2.
Crystal size: 2.8cm x 2.4cm x 0.5cm. octagonal/rectangular

Probes on each of the Y axis (long side):
Tapping on flat topside produced little response.
Squeezing (side to side) produced peaks of 30mV.

Probes on each of the x axis (top and bottom flat sides):
Constant pressure on flat sides (x-x) produced a constant 100mV.
No other results.

Probes on each of the Z axis(end to end):
Taps all round produced peaks of less than 20 mV.
Gently squeezing end to end along z axis produced 90mV-150mv

Conclusions;
The smaller crystal produced more voltage.
Piezoelectric effect was observed.
The piezo electric effect was strongest (Experiment 1) when pressure was applied to the flat sides (x) axis.
Some of these results are consistent with the arrangement in the cartridge. Inside a TC8 Mono cartridge the 2 contact foils are pressed against the 2 flat surfaces (x) of the crystal element. The mono stylus flexes the crystal from side to side as though the flat surface had pressure applied.
Please correct me if you think its different.

Improvements
The Heath-Robinson system of hook-up from the crystal to the Digital 'scope needs improvement. The leads from the crystal in the TC8 Mono cartridge are very thin foil connecting with fine wire leading from the cartridge pins to the amplifier. The wires from the electrodes need to wire directly into the mic input, not be wound round the 3.5mm jack.
Some conductive paste could be applied to increase conductivity from the Rochelle to the home-made electrode plate.
The digital scope could have been calibrated before use to check the input was reading correctly. In the excitement I forgot to do that. I will calibrate it later.

5 Attachments - one to follow
That's it for now. The crystals are growing bigger each day. My next post will show the images of the crystal farm.

[_Cosmic_]

Final Attachment number 6

[_Cosmic_]

***UPDATE***

I was just examining my equipment when I made a discovery.
I was using parts from a broken Nexus tablet I took apart the other day to make my electrodes. I just thought I would check the conductivity of the metal. I made a shocking discovery..can you see the copper coloured strip on the inside of one of the electrodes..it's an insulating material!
This almost certainly means that where I didn't get results in some of the experiments it was almost certainly because the crystal was in contact with the insulating strip. I have now removed that.

I will repeat the experiments again. I have some thin copper flexible material that's adhesive on one side that also came from the nexus. I will try to make use of that too. Captured on the attached image.

***There's hope on the horizon.***

Many many thanks to the two kind members who asked if I would like an oscilloscope FOC.

[Refugee]

Conductive paint should work for connecting the wires if you are prepared to wait for it to dry.

[Herald1360]

There is adhesive copper foil with conductive adhesive available. It's used for EMC bodgery. It's not particularly cheap though it can also be used for things like slug proofing flower pots!

https://www.amazon.co.uk/Shielding-R...1I1XNY1E&psc=1

Is a possible source.

Whether it would stick to Rochelle salt, I've no idea......

[_Cosmic_]

Originally Posted by Herald1360

There is adhesive copper foil with conductive adhesive available. It's used for EMC bodgery. It's not particularly cheap though it can also be used for things like slug proofing flower pots!

https://www.amazon.co.uk/Shielding-R...1I1XNY1E&psc=1

Is a possible source.

Whether it would stick to Rochelle salt, I've no idea......

Yes I have some of that I kept when I dismantled a Nexus. It's in the background of one of the images I posted yesterday I think. You wouldn't stick it to the crystal would you as the adhesive would presumably form an insulating layer?
I just tested it and the adhesive side isn't conductive.
I was considering using it to stick to some kind of testing holder where the rock could make contact with the copper surface.

[ben]

Some more dipping into the BSR book has turned up a bit of personnel info. Dennis Oakley and Ron Corlett (Stourbridge factory) were two names responsible for working on designing and quality control of pick up cartridges in the early 60s, so I expect these would be the crystal/TC8 types.

[_Cosmic_]

Originally Posted by ben

Some more dipping into the BSR book has turned up a bit of personnel info. Dennis Oakley and Ron Corlett (Stourbridge factory) were two names responsible for working on designing and quality control of pick up cartridges in the early 60s, so I expect these would be the crystal/TC8 types.

That's fascinating. I did some searching about and can't seem to find any contacts for them as yet. I will spend some time on it later. I guess they would be in their 80's 90's now but that doesn't mean they aren't still around, just that they aren't likely to be on social media.
I also think that someone associated with BSR might have contacted the thread by now if anyone was still about as it comes up in a BRS search..
I guess we are about 10-20 years too late with all this. Someone should have learnt how to make the elements way before this. I know that they are only mono but there were plenty of crystal stereo cartridges produced AND there's plenty of people wanting to repair or buy mono TC8's isn't there.

[_Cosmic_]

The thread so far:
Ben Madrid/Wirral, our forum member has discovered that Dennis Oakley and Ron Corlett worked at the Stourbridge factory and were responsible for designing and quality control of pick up cartridges in the early 60s.

Rochelle Crystal Research so far:
Very large (size not known yet) Rochelle salt crystal "bars" were produced in insulated rocking tanks that automatically rocked optimally at 4 times per minute. The rocking prevents formation of small crystallites and promotes growth of the larger crystal.

The large rock was then sliced with a bandsaw, initially, perpendicular to the x-axis. This is because the electric effect is greater along the x-axis. These are called "sheer plates". The slices were then sanded to size.

Two "sheer" cut plates were often cemented face to face to form a "Twister" (or a "Bender" element) to be used in this way in crystal cartridges. "Twister" type were produced under the trade name Bimorph.

The optimum piezoelectric output is at "room temperature".

My "Twister" and "Bender" research source is a print-out extract, possibly dating from the 1930's-1940's but doesn't specify the origin. If I come across the source I will attach it to this post.

That's it for now.

[_Cosmic_]

Originally Posted by Herald1360

There is adhesive copper foil with conductive adhesive available. It's used for EMC bodgery. It's not particularly cheap though it can also be used for things like slug proofing flower pots!

https://www.amazon.co.uk/Shielding-R...1I1XNY1E&psc=1

Is a possible source.

Whether it would stick to Rochelle salt, I've no idea......

That stuff on Amazon looks ideal Chris. It should stick to the rock.
It's strange that the same sort of stuff I retrieved from the Nexus had non-conductive adhesive. Simply a different product I guess.

[_Cosmic_]

I'd like to personally thank Unitelex, Chris our forum member in Manchester for contributing to the project by donating his Micronita Oscilloscope which arrived unscathed via carrier unexpectedly fast on Saturday. Huge props. It's very much appreciated. Thank you Chris.

[_Cosmic_]

As promised here are two images of a selection of crystals taken from the "mother liquor" growing dishes.

I have about 70 crystals of varying sizes, in the growing medium, still increasing in size.

The next step is to select a suitably sized sample and attempt to sand it to size and fit the ends to the TC8 rubber holders.

[John10b]

That’s very impressive Chris, well done.
John

[_Cosmic_]

Today I thought I would try making a crystal element and fit it into a cartridge.

Firstly I prepared a TC8 cartridge by cleaning out the inside, the crystal mounts and the foil and plate/pin contacts.

I selected a suitable crystal and drew on the final size with a marker pen.

I sanded down the crystal with glass-paper to 15mmx5mmx1mm.

The finished crystal was inserted into the rubber mounts carefully ensuring the each separate contact foil makes contact with each x-axis face.
Continuity was tested between the plate/output pin and the foil strip contact with a multimeter. The cartridge was then reassembled.

Voltage tests.
Using the CRT scope on high amplitude:
No significant voltage was generated when the element rubber mount was moved to simulate the stylus being moved with a finger although a large spike was observed when tapping.
I tried closing the cartridge tighter in case the contacts were loose. It seems the in the process I snapped the crystal a third way down it's length.

I removed the broken section and re-mounted the shortened element.
Both CRT scope and digital showed no significant voltage being generated either by tapping or flexing.

I then simply tested the crystal by flexing, compressing and tapping in it's rubber mount with the scope probes connected directly to the foils. No significant voltages were observed.

All the images coming up of the entire process..

[_Cosmic_]

More images.
Any suggestions from the forum members?
I'm just having a think..
Here also is a photo of Chris's Micronita CRT oscilloscope just for fun...

[John10b]

Chris you must be disappointed with the results, unfortunately I am unable to offer any advice. I have been following this interesting topic from the start and I hope it’s not the end of your endeavours.
John

[_Cosmic_]

Originally Posted by John10b

Chris you must be disappointed with the results, unfortunately I am unable to offer any advice. I have been following this interesting topic from the start and I hope it’s not the end of your endeavours.
John

Well it's more like the results are unexpected rather than me be dissapointed. I'll plod on for a bit longer just in case I come up with anything.
There's so many variables that its hard to decide what's wrong.

Could be that something is wrong with the Rochelle solution concentrations so they are not forming properly so don't actually have any piezoelectric properties. It effect ought to be very obvious as they are supposed to be very high output.

Could be the foil contacts arn't conducting from the crystal surface or I'm not flexing the crystal enough. It's easy to break them. I'm trying to simulate the way a stylus would move when attached to its mountings.

I don't really know what voltages I am seeing on the CRT scope. I tried calibrating it with a 1.5V battery on DC as Chris suggested but I don't really know what the output amplitudes represent on AC. I think its really small though when you take the look of the lead capacitance waves out of the equation.

I'm getting very low readings from the digital scope too so I really don't think the crystal is emitting much.

I'm unsure how the original inventers thought this would be a good path to go down, but it must surely work somehow. Those crystal cartridges were very very sensitive and emitted around 2 Volts.

I have been experimenting today and have more stuff to document on the thread later but not good results I'm afraid.

Perhaps someone else could try to replicate these experiments?

[John10b]

Chris just a suggestion, can you hook up the experimental crystal to the input of record player amp?, I think you may have done this before, I do this when I’m checking old cartridges, I also use my scope just to measure the voltages. I use a known good cartridge as a simple reference before I start, and just rub my finger on the stylus, I then set about testing some old discarded cartridges. I know this is not an answer to your crystal problem but instead of trying to see the scope you can hear it on the amp.
I also observe from your latest pictures that the crystal seems to be held rather firmly at the yoke, I may be completely wrong, it’s just a thought.
John

[Hartley118]

I'm sure that it's worth pursuing this project further: the fact that you've already achieved a voltage output is very impressive. Hoping to reproduce the performance of a TC8H cartridge without all those years of painstaking development from BSR, and before them Cosmocord, Astatic, Brush et al may be a bit ambitious.

AFAIK, a Rochelle salt sensor is different from a ceramic piezo element in that it doesn't need 'poling' - the piezo equivalent of magnetising a magnet, requiring a strong electric field to be applied to the element to align the 'cells'. A Rochelle salt element on the other hand needs no poling because its crystal cells are pre-aligned in the crystal structure, implying that a single crystal should give the biggest piezo effect. A rather rapid crystal growing process is likely to produce a complex structure with the big crystal actually containing multiple internal crystal boundaries which upsets the cell alignment and probably reducing the piezo effect.

So it's probably worth testing a number of your crystals. The smaller ones may be more effective than the bigger ones because they have a more regular structure.

Of course it goes without saying the the crystal needs to be perfectly dry: any water that isn't locked into the crystal structure will load the output signal.

Martin

[_Cosmic_]

Experiments with Crystal element Number 2.

I constructed another crystal element, this time leaving a bit more bulk in its centre. I also adjusted its length to 16mm so it wouldn't move as much in the cartridge thus preventing the mount at the stylus end from slipping off the element as it had done previously.

The voltage signals were equally as disappointing both using the CRT and digital scopes. I tested the element by flexing slightly along the x-axis and also every other possibility. I also tapped the element at various positions.

I tried adding a drop of Rochelle salt solution on the 2 X-axis faces, close to the foil strips, to ensure they made a better contact.

I then took the assembly out of the cartridge and secured it in a vice. I connected the contacts directly to the CRT. No significant signals were present.

I then took off one probe and touched it directly onto one of the x-axis surfaces and added a drop of Rochelle solution.

Surprisingly it seemed to activate the element and numerous "large" peaks were registered on the CRT. However the CRT gain was set on the maximum setting. I wasn't able to replicate this result again.

So, I'm back to the same conclusions of the experiment I did yesterday.

However, I have one last thing to try and that is to add a conductive gel to the foil/element contact points to see if conductivity at these points is the problem. I suspect it might be.

Any suggestions from the forum?

Here are the images.