TESORO GOLDEN SABRE

[Qiaozhi]

No Nelson, 255x137mm are dimensions only for one "D" you have to make...Not both togather!


Quiaozhi, aint no calculator solved me neither one coil so far. All those are pure theoretical....As old radioamateur i can swear on this!

Regards!

Hi Ivconic,

I've just wound a DD coil after calculating the number of turns using my coil calculator. It was correct first time!
No need to "wind up again and again....".
Theory and practice can sometimes match.

[ivconic]

D


No Nelson, 255x137mm are dimensions only for one "D" you have to make...Not both togather!


Quiaozhi, aint no calculator solved me neither one coil so far. All those are pure theoretical....As old radioamateur i can swear on this!

Regards!

[Qiaozhi]

Forget calculators....schmukctors! Work!


Actually i faced huge problem here;


Difference was in 4-5mm....Hell of a job to wind up again and again....

That's why it's useful to start off with a coil calculator.

[nelson]

Hi Max and thanks for orient me on where to look for LM308.

Well, here we have something that is call "mercado persa", a place where you can find losts of used and new things, losts of electronics parts, electronics boards, old radios, tv, computers, etc. So i hope this weekend i have the time to go there to see if i can get this hard to find device.

Regards

Nelson

Hi,
LM308 was employed in many old design of audio stuff, guitar effects, rats, mixers etc etc and also early cd-drives and laser-disc readers by e.g. philips.

At now is almost impossible to find in that kind of stuff... but if you have old stuff maybe you can.

Some cd/laser-disc player were used also in some arcade games and recreational devices for public places.
I saw some of them years ago and there were too lm308.

About computer... I think that if present there maybe was in some magnetic or optical device/per. not computer itself.

It was largely employed cause of limited noise, relative hi-input impedeance and low distortion.

Best regards,
Max

[Max]

Ok Ivconic, so you mean this forms and dimensions?

What about nulling separations, do you have demensions?

Any news about LM308 replacement, cause i haven´t any luck on findind this part here on my country. Some people said that old computers have this on the board, but i m not shure wich computers.

Thanks and best regards

Nelson

Hi,
LM308 was employed in many old design of audio stuff, guitar effects, rats, mixers etc etc and also early cd-drives and laser-disc readers by e.g. philips.

At now is almost impossible to find in that kind of stuff... but if you have old stuff maybe you can.

Some cd/laser-disc player were used also in some arcade games and recreational devices for public places.
I saw some of them years ago and there were too lm308.

About computer... I think that if present there maybe was in some magnetic or optical device/per. not computer itself.

It was largely employed cause of limited noise, relative hi-input impedeance and low distortion.

Best regards,
Max

[nelson]

Ok Ivconic, so you mean this forms and dimensions?

What about nulling separations, do you have demensions?

Any news about LM308 replacement, cause i haven´t any luck on findind this part here on my country. Some people said that old computers have this on the board, but i m not shure wich computers.

Thanks and best regards

Nelson

Forget calculators....schmukctors! Work!
Here are datas for another deep coil;

-DD coil used wire 0.25mm(0.28 with varnish)
-"D" shape former 255mmx137mm (suitable for Bulgarian plastic housing),
-102 windings for TX ....6.00 mH
-108 windings for RX ....6.60 mH

2cm nickel coin detects in air at 35cm,no false signals...very stabille!


Actually i faced huge problem here;

So far i first made coil, than searched for various plastics for housing, but at this one i already had Bulgarian housing and had problems when nulling in it...When nulled coils cant fit into housing!? Few mm's over !

So i had to correct size of winding former a bit, later when nullled to fit exact the given housing....Huh! At the end it is working very good....Now i have standard winding former for bulgarian "27"cm housings...
Difference was in 4-5mm....Hell of a job to wind up again and again....

Try this, you'll have best coil so far, for TGS...

regards!


P.S.
Dont have prepared photos, maybe tomorrow i'll post those...

[ivconic]

Another Coil!

Forget calculators....schmukctors! Work!
Here are datas for another deep coil;

-DD coil used wire 0.25mm(0.28 with varnish)
-"D" shape former 255mmx137mm (suitable for Bulgarian plastic housing),
-102 windings for TX ....6.00 mH
-108 windings for RX ....6.60 mH

2cm nickel coin detects in air at 35cm,no false signals...very stabille!


Actually i faced huge problem here;

So far i first made coil, than searched for various plastics for housing, but at this one i already had Bulgarian housing and had problems when nulling in it...When nulled coils cant fit into housing!? Few mm's over !

So i had to correct size of winding former a bit, later when nullled to fit exact the given housing....Huh! At the end it is working very good....Now i have standard winding former for bulgarian "27"cm housings...
Difference was in 4-5mm....Hell of a job to wind up again and again....

Try this, you'll have best coil so far, for TGS...

regards!


P.S.
Dont have prepared photos, maybe tomorrow i'll post those...

[Qiaozhi]

Find a free download called CoilCalc. It is pretty cool. There are other coil calculators. Qiaozhi posted one I think he created. There are many free coil calculators that can be found on the internet. You just have to look! (Use Google.) Also, find some wire specification charts so that you can convert wire guage to diameter, and to help calculate ohms per unit length of wire. There are many free coil calculators, and many MANY wire guage conversion /specification charts. Nobody can do the work for you. You must remember that "coil calculators" are only as good as the data you feed them. Also, remember that the calculation results will probably be based on assumptions that are, more than likely, counter to your intended goemetry! X, Y, and Z (length, width, and height) dimensions must be FUDGED. For instance: is your coil shaped more like a donut or a tube? Or is it planar? And, boy howdy they are different. THINK about how the data you are entering will be interpreted by the computer. You can also use a pencil and paper and research the coil formulas!! (Just kidding, don't do that.) No, I'm not kidding.

The problem wih CoilCalc is that it is based on Wheeler's Equation, which is only good for calculating single-layer coils such as solenoids. My own calculator is based on Brook's Equation, which is more suitable for a multi-layer coil like those found in metal detectors.

[porkluvr]

Coils, what's that?

Dino - firstly, be practical. Please do not expect to perform magic if you do not have some necessary test equipment. Over and above a basic multimeter, it is a very good idea (that's putting it mildly) to have an inductance tester. An LCR meter is very convenient, and a cheap frequency counter is also a good idea.

I purchased a combination meter from an Ebay store last week, (a long overdue investment). It's a Mastech MS8222, that I got for a reasonable price. My new meter is NOT fancy, but it measures "L-C-R", and even frequency to 20kHz. It has reasonable accuracy and resolution specifications. It seems to be adequate.
If you don't already have LCR and frequency measurements covered, then you should look into it. I know that I am "lucky" by being in Ebay's backyard, but I think that you can probably find international sales.

Find a free download called CoilCalc. It is pretty cool. There are other coil calculators. Qiaozhi posted one I think he created. There are many free coil calculators that can be found on the internet. You just have to look! (Use Google.) Also, find some wire specification charts so that you can convert wire guage to diameter, and to help calculate ohms per unit length of wire. There are many free coil calculators, and many MANY wire guage conversion /specification charts. Nobody can do the work for you. You must remember that "coil calculators" are only as good as the data you feed them. Also, remember that the calculation results will probably be based on assumptions that are, more than likely, counter to your intended goemetry! X, Y, and Z (length, width, and height) dimensions must be FUDGED. For instance: is your coil shaped more like a donut or a tube? Or is it planar? And, boy howdy they are different. THINK about how the data you are entering will be interpreted by the computer. You can also use a pencil and paper and research the coil formulas!! (Just kidding, don't do that.) No, I'm not kidding. Oh boy, my brain is getting soggy so I'll wrap this up.

Oh, yes, don't neglect to read over the previous thirty or so pages of this thread - and other related threads - for some good ideas.
Good luck!

[dino]

Golden Sabre

Hello all.... well i have some questions for you guys... i have a original placstic sonde 25cm for DD coils, and im interested if someone can help me with number of coils for RX and TX for Golden Sabre.... i hope someone reply to my request.

Best regards Dino

[Max]

oh , please Max , for VLF metaldetector what frequency is

better ? (about sensivity , deep ,..)

Hi Sisco,
now I understand... you ask which frequency is better to gain sens and avoiding troubles...

First: it's not so critical factor for sens as on can think.

Well any frequency from 5KHz to 15KHz is fine for this, you have big response from foil without a good disc circuits if use higher frequencies e.g. near 20KHz.

At higher than 8-9Khz frequency you gain depth for smaller objects even thin ones, but have more ground and moisture influence. Need a good coil to run ok and a good design too.

At 5KHz operations are often so smooth, relaxing but most depends on circuit used.

I found e.g. Tesoro's really good running at 10KHz (bandidoII) and 14KHz (GSabre)... stable deisgns, cause are good designs! Of course you need also good coils for them.

I think that a detector running at 5KHz can avoid some problems in e.g. simple designs but low freq. is not required if design is good and disc is present.

Another thing to keep in mind is time response of detector that, if motion type, could be affected by a bad design and a low operative frequency.

Kind regards,
Max

[sisco]

oh , please Max , for VLF metaldetector what frequency is

better ? (about sensivity , deep ,..)

[Max]

about Useable frequency in VLF metaldetector ? (between ? KHz to ? KHz)

Hi Sisco,
sorry for the latency,
VLF frequencies ?

To be more technical in theory VLF is from 100 to 10Km wavelenght... that means about from 3KHz to 30Khz.
... in practice anything from e.g. 1-2KHz to e.g. 20 KHz or more... is suitable.

Kind regards,
Max

[sisco]

about Useable frequency in VLF metaldetector ? (between ? KHz to ? KHz)

[Max]

about frequency how ?

Hi,
Colpitts formula for the TX frequency (signal at TX coil).
LC circuit formula for RX resonance, if you need to know it I mean.

When circuit operates RXfrequency=TXfrequency cause coil is an air-core transformer... but you may have (and in tesoro's is always so) a different resonance frequency at RX LC circuit.

That cause full-resonance coupling is much more complicated to be realized in series, giving reliable results, by factory process.

Kind regards,
Max