TESORO GOLDEN SABRE

[Max]

Hi,
Max.
Nice to hear you have made this coil!
I still cant get this results?!??!!??!?!
And cant find the reason.I have sealed one in plastic case,but can reach about 25 cm.This is not good!
Can the reason be that I try with Ivconics first post for this 255 X 137 coil - TX 102 and RX 108!
Try everything changing the leads and many other things!
Also I cant find point where I dont get the signal from ferite piece!Or when I find such the detector also dont make sound and for coin!?!?
Damn still cant test I am MAD about this!
Thanks

Hi,
it's strange, I've done at first attempt required 2 days for getting the good results... but much more for epoxy sealing.

I've used TX=100 and RX=105 wire 30AWG(0.25 without varnish)... have you took a look at my pictures ? I've made using plywood board and nails for former... very easy.

My problems were with epoxy this time took 1 week! Damn slow epoxy... but is really hard at the end... it's slow type for surfboards!

I think your problem is not in few turns more...but in nulling or shaping.

BTW if you have wrong preamp you cannot reach that performances... as I wrote about some posts ago. You need an LF353 or at least a TL082 to get good results... or something really close or better. Not easy task replace LF353 here.

Also you have to mount LM308 or TL082 or TL072 and avoid using the TL062 instead of LF442 of original if you have the notch equipped.

Best regards,
Max

[Max]

Max,
How you null to "Nulling is (at now) around 4.5mVpp"?
What do you understand buy this?
Please explain because I am begginer and have no idea what this mean!?
Thank you

Hi,
it's easy... when I test for null I connect TX leads of coil to tx pads on pcb (so to the oscillator section) then I connect the RX leads on a dummy load like this:

1 poly-capacitor (in this case it's 15nF)
1 resistor of 1Kohm

The two components are in parallel and rx leads are connected parallel to... so you have an LC resonant circuit + a dummy resistor load that avoid full resonance appear when energized... and you got same frequency as in tx side (air core transformer).

I connect it to scope probe and read values for minimum signal... moving a bit in the central area...or sliding one coil e.g. TX over RX...you can get something good for DD coil like that from e.g. 20mVpp to few mVpp... less you read is better.

I reported peak-to-peak value of my readings but you can express in other terms cause signal is sinus. I use it cause I see directly watching the amplitude of sinus on the screen... so it's easy for people having just old analog scope compare with my results.

Reached a good "null" I fix coil parts still free with some tape or other stuff... then I use epoxy to seal for real use... cause you need it very rigid and no movements inside housing.

Best regards,
Max

[Qiaozhi]

Hi,
all about right... but mine is not silver. From what I know my 1/2 crown of 1967 (that I often use in tests) is made of an alloy of copper/nickel.

According to

http://en.wikipedia.org/wiki/British_half_crown_coin

from 1946 the 50% silver half-crown was adbandoned for the copper/nickel alloy version. Then it was demonetised in 1970... with the decimal system introduction.

Kind regards,
Max

Could be. The half-crown I measured was a George V from 1936. My Garrett GTAx1000 gives #9 on the display, whereas a hallmarked silver target displays #10. So it doesn't appear to be pure silver. However, a 1957 half-crown shows up as #5.5 and a 1960 as #5. These are all metal detector finds, and the 1936 coin is not discoloured, whereas the other two show signs of corrosion.

hi

Max,
How you null to "Nulling is (at now) around 4.5mVpp"?
What do you understand buy this?
Please explain because I am begginer and have no idea what this mean!?
Thank you

[tiktak]

Hi,

Hi,
Ivconic well done!
You make me crazy!I still cant get my TGS working and you pick up 256 roman coins for 5-6 hours!!!NICE.
I dream to find ONE.

[tiktak]

Hi

Hi,
Max.
Nice to hear you have made this coil!
I still cant get this results?!??!!??!?!
And cant find the reason.I have sealed one in plastic case,but can reach about 25 cm.This is not good!
Can the reason be that I try with Ivconics first post for this 255 X 137 coil - TX 102 and RX 108!
Try everything changing the leads and many other things!
Also I cant find point where I dont get the signal from ferite piece!Or when I find such the detector also dont make sound and for coin!?!?
Damn still cant test I am MAD about this!
Thanks

[Max]

Yes i also noticed that TL082 can be used there. You said 80-90%...i'll dare to say 95%...
For JRC2068 than should be 90%....
Havent tested 4558,1458,4559...simillars...

Hi,
yes maybe is more than 90%... just my impression with the one I had tested (is an STmicro manifactured part).

I haven't tested 4558 (as far I remember) but LM358 and 1458 yes and both seem no good like TL082.

With TL072 I get the exact behaviour of TL082 (both from STmicro).

So till now I haven't found any better replacement for LF353 there.

Kind regards,
Max

[Max]

On behalf of Max - a Half-Crown is 32mm diameter, 2mm thick, and it's a silver coin.

Hi,
all about right... but mine is not silver. From what I know my 1/2 crown of 1967 (that I often use in tests) is made of an alloy of copper/nickel.

According to

http://en.wikipedia.org/wiki/British_half_crown_coin

from 1946 the 50% silver half-crown was adbandoned for the copper/nickel alloy version. Then it was demonetised in 1970... with the decimal system introduction.

Kind regards,
Max

[Qiaozhi]

Hi Max. Who is the dimension of the coin ???
Regards

On behalf of Max - a Half-Crown is 32mm diameter, 2mm thick, and it's a silver coin.

[Geo]

TL082 detection at 80-90% (good) , same coin (1/2 crown), noise bursts
LF353 maximum detection (100%) , same coin, some erratic noise at max sens (really few)

At 100% coin is detected at 38 cm loud.

Best regards,
Max

Hi Max. Who is the dimension of the coin ???
Regards

[ivconic]

Yes i also noticed that TL082 can be used there. You said 80-90%...i'll dare to say 95%...
For JRC2068 than should be 90%....
Havent tested 4558,1458,4559...simillars...

[Max]

Hi all,
I've made some little tests with different ic as preamp ...cause my epoxy is really hardened now... seems a rock

Ok... here the results with TGS-clone+255*137mm DD coil

Preformace are referred to that I got with LF353 in place, that so it's 100% (or the unit):

MC33178 very weak detection at few cms from coil, noise bursts present
TLC2262CP detection at 25-30% (bad) for a copper-nickel item, few noise at max sens
NE5532 detection at 70% (medium) for the same copper-nickel, no noise at all
TL082 detection at 80-90% (good) , same coin (1/2 crown), noise bursts
LF353 maximum detection (100%) , same coin, some erratic noise at max sens (really few)

At 100% coin is detected at 38 cm loud.

So seems that LF353 is really tailored here on the TGS!

The total failure of MC33178 is really strange to me... cause I got very good results with it on bandidoII... but that's life.

Best regards,
Max

[ivconic]

Last time i've been in Munich was in 1987. Long time ago, but still remember that they washed streets with beer, early in the morning.....Funny, at the time i gone there especially to buy new computer - Amiga 500!!! I had Schneider CPC6128+CTM664...and decided to buy Amiga 500 due much better performances. Schneider 6128 was 8-bit machine, but Amiga was among first 16-bit machines than!!! What a step it was!!! But....! Amiga is lost in time and Schneider CPC6128 is still alive and kicking...i have it here at my workshop. From time to time i switch it ON just to fill up capacitors and "refresh" circuitry....Still is in good shape,workable.... I wrote so many stuff than, in Locomotive Basic!!! SSSHeeeeeshhh!!! What a history!
Also i do have AtariST520 in excellent shape too....But my first computer was ZX Spectrum in 1981. Than C64 in 1982. Than CPC6128....
Now i have Siemens&Fujitsu 64-bit....blah,blah....
What a history hah!?
Thanks Zemljak! I'll try that...
Regards!

[Max]

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!

Also water based is possible... aquadag or something is the commercial name... recipe is (about):

-demineralized water
-graphite (very fine and pure powder)
-tannic acid (the same of wine... and tea but pure and concentrated)

The mix and exact parts I don't remember... but tannic acid used to break particles of graphite into colloidal particles size...in the water.
All stuff must be mixed at moderate temperature... heat make it easy the melt of graphite grains into small colloidal size agglomerates.

Best regards,
Max

[Max]

Beer or the girls.Grt Nakky.

Both. (not these of the picture of course... they are from oktober fest website )