TESORO GOLDEN SABRE

[Hush]

Hi Ivconic.
Try to put graphite powder into nitro varnish, varnish it, then wait to dry about 24 hours.
I've also tried to do that but not at coil yet. First try it on some other material. Hmmm.. nitro varnish.. did I wrote it properly on english? If not, please correct it . U pitanju je nitro lak naravno.
Regards!

[nakky]

Hi...
I wrote many times "power" instead of "powder"... damn!

Have to drop keyboard in the trash can or drink less beer at evening.

(but I like "oktober fest" very much )

Kind regards,
Max

Beer or the girls.Grt Nakky.

[Max]

Hi...
I wrote many times "power" instead of "powder"... damn!

Have to drop keyboard in the trash can or drink less beer at evening.

(but I like "oktober fest" very much )

Kind regards,
Max

[Max]

Max, i was thinking to mix graphite powder with some plastic and make mass to fill up coil housings. Than must put a piece of naked wire in it and later connect to gnd...What do you think? All those to get rid off Al foil finally...

Hi,
I've done before... using epoxy and also acrylic-based varnish.
My results were no good, the problem is related to the fact epoxy and varnish are not conductive and so when grains of graphite mix with them grains are partially covered by insulant and so you lose some contacts between them.

As far I remember also big quantities of graphite are needed for low resistance maybe 1Kg for 2liters solution or the like.

Some are still in production like maybe acquadag or oildag varnishes.

Preparing at home is possible but you need pure tannic-acid and lot of graphite powder.

I've found much better using graphite-based spray... very very good like Contakt's products (from the Nederlands?) or other brands too. Very thin film... very good conductivity in our range of interest for VLFs.

Problem is that now a 300mL can costs 10-15euros... and also spaying that stuff is really unhealthy and dangerous for lungs etc if you don't use a good mask/breather... too many micro-particles cause it's colloidal dispersion of graphite in solvents (ether) and + some fixing agent (acryl most of the times).

You can find similar stuff sold for fishing-rods... carbonium type... as lubricants and protective paint: it's about the same thing... conductive and good for shieldings... and price is lower than electronics products.

Same thing for some other mechanics lubricant spray...all the same: colloidal graphite in ether.

For homebrew... I've found a pure graphite power very good... used as lubricant for ball-bearing stuff and similar. If you first pass acryl laquer and then before it dry you leave power drop over it then you'll make good things.
After that I found I need to "align" power grains with a piece of paper scrub... after total dry (20minutes)... results are good but too work and care needed for great surfaces and spray is much better.

Kind regards,
Max

[ivconic]

Max, i was thinking to mix graphite powder with some plastic and make mass to fill up coil housings. Than must put a piece of naked wire in it and later connect to gnd...What do you think? All those to get rid off Al foil finally...

[ivconic]

June,Jully and Avgust are best for prospecting here...

[ivconic]

Summer of course. Winter is ugly here, to cold for my tatse. Not possible to prospect due lot of snow (i live deep in mountains)...In summer there are a lot of snakes but who cares about them? I dont...
Regards!

[nakky]

With or without coil, you are always welcomed here Nakky!
Regards!

Ivconic,very nice of you,I will keep in mind,I am serious think about it.What is the best time of the year to come.Grt Nakky.

[Max]

Hi,
anyone have/had experiences with this product ?

It's a fast epoxy for model airplanes... 9oz total...(about 250gr) my only thought related to problems is about the peak of temperature... cause 30 minutes mean an hi-peak... some temp. fixing can break... some plastic melt etc

Anyone knows ?

Best regards,
Max

[ivconic]

Thanks Max!

Thanks Max! Good explanations.
According to all my experiments up to now, i can swear that problem occurs somewhere arround LF353 and first kop's - geb&disc stage....It has something to do with phase....almost certainly!
Although i started to think to mod oscillator also...JC1 stated something about inperfectabillity of fet stabilisation at osc. stage...
It will be good to experiment there....

[ivconic]

Hi Ivconic,I have original coil 20 cm cc.I will bring it to you,than I can also have a look at you romain site and pick up a lot of romain coins.TGS with original coil and 1M over 4148 is also noisy,10M will reduce it.But with DD coil it is more noisy ,10M will also reduce it a litle.I think DD is very sensitive?Grt Nakky.

With or without coil, you are always welcomed here Nakky!
Regards!

[Max]

Hi Max.

Look out : polyester can shrink, so for coils ?? epoxy is OK.

Succes.

Ap

Hi Ap,
yes you are right... it could shrink... I never tested on coils but I'll do some experiments just to see what happens... also with vinylester-resin that is a bit better than poly.

I always use epoxy 2-components... but this time I get a very slow one... and after 3 days and more... much is hardened... but some few is still fluid... bad thing.

At first I thought I've made some mistake in mixing stuff , quantities... but used grad. plastic beker to measure volumes... mixed well... then I start thinking the hardener is old or something... and now I think that take longer in some small parts cause of cold temperatures here that blocked reactions during night.

But this stuff is making me crazy now. Just hope I haven't to rewound these last 2 coils.

What to say... sometimes is better spending some few eur more than getting so long potting time and problems.

Best regards,
Max

[Max]

I replaced LF353 with NJM2068, claimed to be lowdrop,low noise and high gain op-amp...
When switched ON.....no bleeping at all.In All metal mode and in Disc mode!
Both! Even when Sense is at max.
But i lost that "soft" sound like it was with LF353. Now it is sharp and consistent...strange!?
Depth is same as with LF353...Havent checked on the field yet, only in workshop...

No i dont think that LF353 was bad choice. I think that LF353 is proper choice, but i must have some other problem here and at the moment NJM2068 suits better here than LF353...??? But what???
I have feeling it has something to do with phase...or have great influence on phase. Cose i noticed certain differences on phase shift, between cases when LF353 is on pcb and case when NJM2068 is on pcb???
There should not be any differences theoretically? But there are?
Also i played with 5K1 at RX coil inputs...No differences from 6K8 to 3K3???
Than why the hell 5K1??? From 3K3 to 6K8 is bleeping all the time and depth remains the same....
But without resistors (RX coil directly connected to LF353 inputs) NO BLEEPING...but less depth too..???
It seems that only weak signals producing bleeps...strong signals NOT??
Huh!
I am waiting my friend to bring me much better scope...and later i will continue experiments...

Hi,
if you reduce noise somewhere before you reduce noise-amplification along the chain of amplifiers. So you changed the LF353 with a lower noise one and get no bleeping, fine.

LF353 has noise level of 16nV/sqrtHz @1Khz
NJM2068 has a flat 0.56uV over a wide range

It's the same as you change noisy (some could be also fake... like the 2 I posted) LM308s with something better e.g. TL071CN from recent ST production.

Total noise impact is less along the chain and you gain better stability.

I'll try in next few days... (at epoxy setting, damn slow thing!) the use of MC33178 as preamp in TGS.

MC33178 has just 7.5nV/sqrtHz @1Khz and it's used in bandidoII.

About resistances the diff. config. of LF353 preamp set a gain of about 40 with that values... but if you reduce input resistors you increase the gain, fact that with zero resistors you get less depth is related to bad impeadance matching between coil and preamp... so your input stage lose part of signal cause of that bad factor. I suggest you increase the 220k to something more to get greater amplification saving impeadance matching.

[Qiaozhi]

Oh, if we are closer! Fact that my country is not member of EU means a lot.
That fact keep Serbia to far away from rest of Europe...on Mars!
Every single,small packet (even plain envelope) will cost damn money for me to send abroad! One my friend send me 3cd's from Holland and payed only 3 euros for that!? If i was about to send simillar to him, it would costed me over 30euros!!! I cant even send money via Western Union from Serbia....can only receive from abroad...goodbye E-Bay! So far this is "deep hole"..i cant escape from here at all. Looking forward, next few years, things to be settled and finally to we get chance to live like any normal people..Until that....only this internet left for us...
Best regards!!!

Hmmm ... 30 euros!
In that case I'll wait until Serbia becomes part of Europe.

Actually I've just checked the postal prices myself between the UK and Serbia, and your absolutely right. I never realised it was so expensive!

[porkluvr]

It's all about power, or and, noise

You go and stick 2 OP27 equivalent in (NJM2068, - by golly they done (as compared to OP27) it at 1/2 the power! a minor miracle!