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La serie umax son lo que evolucionaron a partir de la serie de Sabre, por lo que las bobinas que figuran en la serie umax debería funcionar. La cuestión de la bobina original era el 8 "Ronda concéntricos.
No es suficiente para su bobina de tener solamente buenos profundidad de detección. También debe tener buena discriminación. Tener una "especificación original" bobina de fábrica puede ser una cosa muy buena para que funcione. [/ Quote]
The coils I will price a little expensive. I think I'll build more coils internt. I own 23 awg copper wire (0.25mm) 20 AWG (0.5 mm) and 21 AWG (0.7 mm).
I built a coil in the form of D and I used 23awg wire 120 turns for 110 laps for RX and TX. The results were dismal.
That copper wire which I have can work better and be more manageable to build the coil.
Read my previous post, the results you will not be
dismal with a slightly different view of the Tx coil.
If you look inside a CRT Television Set, or CRT Computer Monitor, you will find a Taped-In Degaussing / Demagnetising Coil as One Single Loop connected to a PTC Thermistor which goes directly to the Mains Power Supply. It's more or less about 0.25mm Taped-In Cu Wire for Big Screen CRT TV Sets, and smaller CRT Monitors may use a somewhat finer Cu Wire. Unrolled, and wound onto a small Toilet Paper Role, you will have more than enought Cu Wire to make a Search Coil in One-Go without having to lengthen it by soldering pieces together. Taped-In (black) CRT TV Degaussing / Demagnetising Coil:
If you look around a little, then you will find most, and have to buy least of the materials needed for the construction of this Metal Detector. Even all the components can be found if you know were to look. Throughout the years, I have removed hundreds, and collected more than three Banana Boxes full of CRT TV and Monitor Taped-In Degaussing / Demagnetising Coils from discarded Sets found alongside the roads here in Holland.
If like me you do not have the money to push, then you will have to push your imagination and creativity a lot harder. And this shore as hell beets living a life by being Brain-Dead
You will find the answer to your question by monitoring the output of the pre-amp, relative to the TX signal, using a 2-channel oscilloscope. If the RX phase-shift is 20 degrees, the RX coil is the correct way round. If it's 200 degrees, then swap over the two connections.
Hi Qiaozhi:
What if he has nulled coil on "wrong" side? Wouldn't that confuse the issue?
We should know the answer to his question directly. However, I do the same thing -- look at the phases on the scope and swap wires if it looks wrong.
Another way to check, as mentioned a number of times, is to check for double-beep when testing with a coin at about 8 to 10 cm. Double-beep usually means leads of one of the coils should be swapped. Of course watch out for the ground wire connections when swapping leads.
As mentioned by dfbowers I think, you can also flip over a coil to change the winding direction. Then make sure grounding is consistent.
I have to puzzle over this a little to convince myself which topologies are identical or at least perform identically.
But really, we should be able to answer this question directly with a diagram. Hopefully someone who has just recently made an excellent working coil will just say which one they used.
One interesting detail about the "AWG" wire system: as you go down by 3 wire sizes, the wire cross sectional area and weight increases 2x (and resistance will decrease by 1/2).
As an example, 20AWG will have twice the weight and 1/2 the resistance of 23AWG (for two wires of the same length). This all may be unimportant but is sometimes useful to know.
What is important is that if you have 0.25mm wire (approximately 30AWG), that is a very good choice for making a light-weight coil for the TGSL. If your wire is instead 23AWG, this will make a coil much heavier than is necessary.
I've been experimenting with heavier wire and found that it may cause other difficulties (besides the weight) because it has less resistance and changes the "Q" of the RX resonant circuit, which changes the amount of phase shift of the received signal at a given offset from the resonant frequency. It also changes the spectral content of the noise picked up. I don't understand these effects at this time, but it might make it harder to get your MD working the same as others using more typical wire gauges.
What if he has nulled coil on "wrong" side? Wouldn't that confuse the issue?
As you start overlapping the coils you will reach a null point. Then continue through the null until you achieve the correct phase relationship. If you cannot get the correct phase difference, then swap over the RX wires. The double-beep test can also be useful.
Rather than simply following a step-by-step set of instructions, it is better to try and understand what is going on. That's why a 2-channel scope is almost a necessity.
As you start overlapping the coils you will reach a null point. Then continue through the null until you achieve the correct phase relationship. If you cannot get the correct phase difference, then swap over the RX wires. The double-beep test can also be useful.
Rather than simply following a step-by-step set of instructions, it is better to try and understand what is going on. That's why a 2-channel scope is almost a necessity.
That clarifies it -- correct phase should be found on the side of null that is more overlapped -- if not, swap wires. Still, it would be good if someone would reference a diagram of a working design -- is it clear in TGSFinal stuff?
BTW: I think he has no scope, making it difficult to run tests (and obtain a wife in some cultures...).
He once blew his scope up, ... killing his wife in the process (a cheap divorce solution I suppose)
About the scope, he had admitted this. But I don't really know if he was married at all
Maybe he does not even like woman
Regards,
Robert
I'm afraid your imagination is more vivid than mine. I was not making any personal comment about lunamay (who I think has done a great job with the tools at hand), just that most MD fanatics consider a scope the essence of life itself and feel rather lonely without one... or something like that...
That clarifies it -- correct phase should be found on the side of null that is more overlapped -- if not, swap wires. Still, it would be good if someone would reference a diagram of a working design -- is it clear in TGSFinal stuff?
BTW: I think he has no scope, making it difficult to run tests (and obtain a wife in some cultures...).
-SB
To try and build your own coils without the aid of an oscilloscope is fraught with problems, and even attempting to construct the TGSL PCB is extremely difficult. I would always recommend buying a commercial Tesoro coil before you even attempt to build your own.
To try and build your own coils without the aid of an oscilloscope is fraught with problems, and even attempting to construct the TGSL PCB is extremely difficult. I would always recommend buying a commercial Tesoro coil before you even attempt to build your own.
I agree. Strict attention to details and good soldering skills are a must. Otherwise, failure is highly likely and troubleshooting without a scope can make things difficult.
Building a TGSL without a scope is not impossible though. I built a second.. no mistakes! Worked perfect from the beginning.
Coils on the other hand are quite a different story. MUST be correct inductance & wire size, balanced with a multimeter or scope AND cast in a suitable housing with SLOW CURE epoxy. Must be absolutely rigid or you will be totally wasting your time. Not impossible though! Enough details exist to make anyone successful.
I'm afraid your imagination is more vivid than mine. I was not making any personal comment about lunamay (who I think has done a great job with the tools at hand), just that most MD fanatics consider a scope the essence of life itself and feel rather lonely without one... or something like that...
Cheers,
-SB
I was not referring to @lunamay, but @Ivconic who nullifies his coils without the use of a scope. And he dose have a scope, but dose not use it for nullifying coils. And I thought that I had read somewhere in this thread that he once blew up his scope during some kind of measurement (?).
And about @lunamay, I am full of praise about his efforts and accomplishments, and have absolutely no reason to talk him down in anyway.
Maybe @Ivconic is like me being a bachelor too, for I can't stick to only one single woman. And it really doesn't bother me at all if partners are man-woman, man-man, or woman-woman. I am very pleased and fortunate to live in such a liberal minded country called Holland.
Here you have an extract from @Ivconic's article about nullifying coils; TGSLCoil Making.pdf
... Nice and fast method in cases when you don't have scope and similar instruments. Now i do have scope and many more instruments...but this method is so accurate and fast that i don't want to bug myself with to much “philosophy” ...
... Well balanced coil detects 1e coin at 30-34 cm distance in air.
@Ivconic has lots of experience in coil making, but for most of us (including me) I think @Qiaozhi gives excellent advice that should not be overlooked.
To try and build your own coils without the aid of an oscilloscope is fraught with problems, and even attempting to construct the TGSL PCB is extremely difficult. I would always recommend buying a commercial Tesoro coil before you even attempt to build your own.
Coils on the other hand are quite a different story. MUST be correct inductance & wire size, balanced with a multimeter or scope AND cast in a suitable housing with SLOW CURE epoxy. Must be absolutely rigid or you will be totally wasting your time. Not impossible though! Enough details exist to make anyone successful.
Don
Soon, I will make a write-up about how to make your own Q Dope
Q Dope has outstanding dielectric properties, and is one of the best coil impregnating compounds known, with very little effect on the coils Q-Factor. It is rather expensive to buy, and is then only available in small bottles. Our Do-It-Yourself Q Dope will have the same dielectric properties as the commersial one, only it will then be even better suited for our coil making applications.
I was not referring to @lunamay, but @Ivconic who nullifies his coils without the use of a scope. And he does have a scope, but dose not use it for nullifying coils. And I thought that I had read somewhere in this thread that he once blew up his scope during some kind of measurement (?).
And about @lunamay, I am full of praise about his efforts and accomplishments, and have absolutely no reason to talk him down in anyway.
Maybe @Ivconic is like me being a bachelor too, for I can't stick to one single woman. And it really doesn't bother me at all if partners are man-woman, man-man, or woman-woman. I am very pleased and fortunate to live in such a liberal minded country called Holland.
Here you have an extract from @Ivconic's article about nullifying coils; TGSLCoil Making.pdf
@Ivconic has lots of experience in coil making, but for most of us (including me) I think @Qiaozhi gives excellent advice that should not be overlooked.
Attachment:
TGSLCoil Making.pdf from @Ivconic
Regards,
Robert
I have spent many hours balancing coils and the way that Ivconic balances his coils I find to be sufficient. The only advantage I see to using a scope is that you can see the results of under coupling or over coupling. You will observe either 20 degrees or 200 degrees Rx signal in reference to the TX signal, depending.
With a multimeter, just connect a 1k resistor and a 15Nf in parallel with the coil while measuring. The thing that is a variable is the frequency response of a multimeter as most are designed to measure the RMS value of a 50 or 60 hz signal. So, what we look for is just the null point.
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