Question about tgsl

[waltr]

Good answer dbanner

[dbanner]

Oki and I read that pdf file by Dbowers, but another question I would ask and I always think about it. That if I made a bigger coils and with the same inductance and resonance for the original coil, so would that bigger coil be deeper from the original?

The short answer is no. The coil size seems to be optimized at somewhere around 8 to 10 inches in diameter, beyond this the ground effects become more pronounced and there is little advantage to depth.
I would strongly suggest you build the DD coil type first, as it is way easier to setup and null. The concentric coil seems easy only on paper, but it is difficult to get it right without much experience.

Make a DD coil first, then you can test your circuit and have a play with all the features to get a good sense of the TGSL operation and how to set the GB trimmer etc, etc. Then you can have a go at the concentric later on when you understand the principles involved in nulling and the final phase offset.

The DD coil goes just as deep as the concentric, it all depends on how much care you put into the construction and proper shielding of your search coil.

Tesoro has a stock widescan coil (DD). So the tgsl works great with either.

[waleed]

If you get real close on the number of turns on the Bucking coil then the little extra wire off the bucking coil is just moved around to finish nulling.

DBowers shows this detail in his concentric coil build PDF. There is a loose extra wind to move around.

Oki and I read that pdf file by Dbowers, but another question I would ask and I always think about it. That if I made a bigger coils and with the same inductance and resonance for the original coil, so would that bigger coil be deeper from the original?

[waltr]

Thank you waltr for the info..well maybe I will first build the concentric then..I read everything about building the concentric coils and I think I would not have any problem about building it..but the thing that I would worry about is the nulling..I know there should be RX and TX/BX but when I null it how would I play with the small loop wire between TX and BX to get the deep null? Like moving it around or reducing the number of turns ?

If you get real close on the number of turns on the Bucking coil then the little extra wire off the bucking coil is just moved around to finish nulling.

DBowers shows this detail in his concentric coil build PDF. There is a loose extra wind to move around.

[waleed]

I have used both DD and concentric on my HH2 PI detector. I like the DD for fields to get more area per sweep but not as deep. The concentric goes a little deeper but does not cover as much area, sensitive only under the RX coil. So I use the DD when targets may not be deep, parks and sport fields and the concentric in woods and for relics.
Others have described the same performance of DD verse concentric with the TGSL.

I have only built and used a DD on my TGSL (very recent build) so far but plan on also building a concentric.
Not sure which are easier to build. The DD seems more straight forward which is why I started with the DD.

I am currently working on my second DD coil for the TGSL. The first one was shielded with aluminum foil and never nulled as deep plus I had a hard time getting the correct phase shift plus detection distance was not as good as other have obtained. The second DD was wound using a 'mechacical turns counter' (I messed up counting the turns) and shielded with Graphite power mixed with Polyurethane 1:1 plus a thin drain wire. This is nulling very well with the correct phase shift. The in Air distance is improved to what others have gotten. Should have this new coil finished in a couple of days.

Dbowers has good documents on building both.
https://sites.google.com/site/dbcoilshells/home

Thank you waltr for the info..well maybe I will first build the concentric then..I read everything about building the concentric coils and I think I would not have any problem about building it..but the thing that I would worry about is the nulling..I know there should be RX and TX/BX but when I null it how would I play with the small loop wire between TX and BX to get the deep null? Like moving it around or reducing the number of turns ?

[waltr]

Hey waltr..yeah I know shielding and nulling would be hard but I have oscilloscope and the basic of nulling and so on..I will post pictures when I finish building and the the coils..

Anyway would you recommend building the DD coils or the concentric coils?

I have used both DD and concentric on my HH2 PI detector. I like the DD for fields to get more area per sweep but not as deep. The concentric goes a little deeper but does not cover as much area, sensitive only under the RX coil. So I use the DD when targets may not be deep, parks and sport fields and the concentric in woods and for relics.
Others have described the same performance of DD verse concentric with the TGSL.

I have only built and used a DD on my TGSL (very recent build) so far but plan on also building a concentric.
Not sure which are easier to build. The DD seems more straight forward which is why I started with the DD.

I am currently working on my second DD coil for the TGSL. The first one was shielded with aluminum foil and never nulled as deep plus I had a hard time getting the correct phase shift plus detection distance was not as good as other have obtained. The second DD was wound using a 'mechacical turns counter' (I messed up counting the turns) and shielded with Graphite power mixed with Polyurethane 1:1 plus a thin drain wire. This is nulling very well with the correct phase shift. The in Air distance is improved to what others have gotten. Should have this new coil finished in a couple of days.

Dbowers has good documents on building both.

https://sites.google.com/site/dbcoilshells/home

[waleed]

PCB look good. Take your time building and checking stages as you build.
The TGSL 101 pdf is pretty good to help show what each section does.

The hardest part is building, shielding and tuning (nulling) the coil.

Hey waltr..yeah I know shielding and nulling would be hard but I have oscilloscope and the basic of nulling and so on..I will post pictures when I finish building and the the coils..

Anyway would you recommend building the DD coils or the concentric coils?

[waltr]

Hello everyone..well I'm really upset cuz I don't have much time for this project..I will take it slowly, anyway so far I have finished the pcd only and bought all the components..well wish me a good luck

PCB look good. Take your time building and checking stages as you build.
The TGSL 101 pdf is pretty good to help show what each section does.

The hardest part is building, shielding and tuning (nulling) the coil.

[waleed]

Hello everyone..well I'm really upset cuz I don't have much time for this project..I will take it slowly, anyway so far I have finished the pcd only and bought all the components..well wish me a good luck

[kt315]

thank you. same situation is not just in your country. we have that but maybe in slightly easy form.
in reality i do not understand why russian tsar period coins are archeology if they have not relation to modern Lietuva.

[waleed]

what country you are? why you can not write your county in your profile?
people want to see what new member is from.

Anatloy
pleasure

Sorry, I edited my profile and put my location, so I'm from Jordan (a country in the middle east) tbh MD is forbidden here in my country (government issues..) so it's a challenge for me to make an md, and btw I'm here since 2012 ^^ but I wasn't active due to studying and works..

[kt315]

what country you are? why you can not write your county in your profile?
people want to see what new member is from.

Anatloy
pleasure

[waleed]

Oh I didn't notice that sry...but can you indicate on the pcb placement where is the sens switch and the (disc/am) switch also. Thank you

Oki..now everything is clear, excuse me it's the first time of me making a device (even thought that I'm an electrical engineering), I will see if I can improve the depth or the sens when I finish it..now I'm going to make it at weekend..see ya all

[waleed]

I think where you have gotten confused is some of the IC's have multiple parts inside. Example is the LF353, LM358 and LM393 are dual. They have two op-amps or two comparators inside one IC.
Example: On the schematic the LF353's are U101a and U101b.

I count 8 IC's on your placement pdf.

Oh I didn't notice that sry...but can you indicate on the pcb placement where is the sens switch and the (disc/am) switch also. Thank you

[waltr]

I really appreciated you all for the replies I love how this forum is active...now I'm going to etch the pcb (I have coppercoated board and ferric chloride..etc). But the problem is I think that the pcb doesn't match the schematic (which I have got them from "tgsl complete detailed" thread)..we can see that there is in total 12 ICs in the schematic while in the pcb placement there is only 7 ICe (regardless of the other components which doesn't match also). Please can you tell me where can I get the right pcb and pcb placement paper??

I think where you have gotten confused is some of the IC's have multiple parts inside. Example is the LF353, LM358 and LM393 are dual. They have two op-amps or two comparators inside one IC.
Example: On the schematic the LF353's are U101a and U101b.

I count 8 IC's on your placement pdf.