TESORO GOLDEN SABRE

[satdaveuk]

That always happens when you "bind" the coil (squeeze the windings together). Only experience will tell you how to plan ahead to get the final inductance you want. In your case maybe you can pull out extra windings (not so easy I've found after wrapping with thread).

It can change again when you shield and glue. It can change again when you set in the form if you deform the coil at all. Just something you have to get used to.

You can try to adjust capacitors to compensate after you coil is finally built.

-SB

Thanks for getting back to me Simon
In your opinion what would be the highest inductance you would go up to before going any further with this coil ie shielding etc.Am I right thinking that the conductvity will go up when adding a shield or is it just the tightning of the coils that does it? so in a nutshell does the shield its self either up the inductance or lower it, i thought the latter but i maybe wrong. As you said it can be offset with changing capacitor values but there must be a limit, and I dont want to end up with a machine not working to its full spec, I want to end up with the same results as the rest of you.
Also off hand what sort of capacitance reading should I exspect between the coil connections, before I lumed the coil it was reading about 27pf but after luming it jumped to around 70pf or more, but that maybe due to the batterys going flat on my meter and I was very tired.
My circuit is almost compleat, just waiting for the 2n2907 to be delivered from china.
By the way simon can I check the frequency of these coils without the pcb?
I have a very good signal generator with sweep plus 2 very good frequency counters plus a rather old but working dual beam scope.
If its possable I would be greatful if you can tell me in detail what to do because this stuff is new to me.
Many many thanks
Dave

[bernte_one]

Just wanted to tell everyone who owns Silvredogs green tgsl edu PCB.

R43 changed to 100k
R44 changed to 33k

Spoted only when I was assembling second one.

With these I got kindof broken sound and air depth reduced. Changed back to 330k and 2k2

is there something i should mod / change on the black/golden board too or is it finally ok?


another questions - who sells selfmade good made coil for tgsl here in europe (such like wiltran in above post)
i think i would buy one my biggest interest at tgsl at this moment is what can i reach with a good made coil instead of mine
if anyone has an offer please pm

[habitbraker]

Traced the PCB out. The only significant differences are below.

The only other things I see:

C14 and C17 are doubled - to 10uF.
R29 and R31 increased from 470k to 1m.
LM7808 decoupling removed.
CD4024 decoupling removed.
100uF decoupling added to U103.

Has anyone else built this from Silverdogs PCB yet?

Eduardos is on the left.

Don

Just wanted to tell everyone who owns Silvredogs green tgsl edu PCB.

R43 changed to 100k
R44 changed to 33k

Spoted only when I was assembling second one.

With these I got kindof broken sound and air depth reduced. Changed back to 330k and 2k2

[simonbaker]

Hi
I just wound the TX coil which was right to specs given on here, only diffrence is my gap between the two plates were 2/16th of a inch which is about 2.5mm. When I measured before luming the coil read 23.5 ohms resistance and 5.321mh inductance.
Now that I have lumed the coil with cotten doubled up I have the same resistance which was exspected but my inductance has shot up to 6.098, I was monitoring it as i was doing it.
I havent used any glue or shielding yet because I thought its best to chat with you people first for advise.
Hope all is well with everyone
Dave

That always happens when you "bind" the coil (squeeze the windings together). Only experience will tell you how to plan ahead to get the final inductance you want. In your case maybe you can pull out extra windings (not so easy I've found after wrapping with thread).

It can change again when you shield and glue. It can change again when you set in the form if you deform the coil at all. Just something you have to get used to.

You can try to adjust capacitors to compensate after you coil is finally built.

-SB

[juka vk]

Hi everyone, i want to build this metal detector but.... i don't know from where i shoud read this thread, from the start or from the end. This thread is full of modifications.
Can someone make a new thread or PDF file with the best (but stabile) version of detector and with all modifications PLEASE !!!!

Greeting from CROATIA !!!

[satdaveuk]

Coil inductance

Hi
I just wound the TX coil which was right to specs given on here, only diffrence is my gap between the two plates were 2/16th of a inch which is about 2.5mm. When I measured before luming the coil read 23.5 ohms resistance and 5.321mh inductance.
Now that I have lumed the coil with cotten doubled up I have the same resistance which was exspected but my inductance has shot up to 6.098, I was monitoring it as i was doing it.
I havent used any glue or shielding yet because I thought its best to chat with you people first for advise.
Hope all is well with everyone
Dave

[dfbowers]

as previously stated, I built TGS, which worked ,but I had trouble with notch filter. I was going to build TGSL, but I settled on TGSL edu, I now get 30 cm depth. I went out hunting a 100 year old high school playfield and found a canadian quarter and some pennies. To my amazement, I found razor sharp discrimination between silver and aluminum. complete discrimination of large steel, but strangely I was hitting old magnetic sensitive beer bottlecaps. Here are some pics of my latest vacuum formed coils. If it is helpful to anyone, I found that you need to get the abs hot enough that its sagging almost to the bottom of the oven, carefully watch it! then you place the frame on the vacuum box, and you will here the rPMs of the shopvac go up, and you will get good detail on your coil shell. On nulling the coil, I hold the top coil while watching the oscilloscope, then drop dollar store glue gun glue on coil points, I then use dollar store $1. epoxy to secure coils further. Then use 24 hr epoxy to fill the coilshell with no movement.
Finally I got a good discriminating reliable detector. I searched the TSGL posts. and saw that the original Tesoro patent allowed bottlecaps? anyone???

Good job on the coil!

Steel bottle caps are always tough. I always dig a few at the beach but most give you some sort of clue, usually a partially broken sound, but dig anyway!

Case in point: I went over to a co-workers house this week and he mentioned that he lost his wedding band a few years ago. I took my Nautilus DMCIIb for some reason. The third target I identified had a really crappy sound, almost like a bottle cap. Usually a gold band will have a sharp, narrow sound with the DISC channel louder than, and about the same time as the AM channel.

Not this one. I marked the spot and walked away. I though that it was a bottlecap. My friend dug it anyway. $##@$!! It was his ring .

[simonbaker]

Hey guys. I have several times downloaded giftpaks etc and been unable to open them.
I want to make Eduardo's PCB but need the program to open his files. I currently use the Sprint 5 software.
Can someone dirrect me to a program that opens .SCH files??

Also while I am asking Questions........... is the TSGL a D-120 disc range?? D-90??
Are any versions D-180?? What range is Eduardos TSGL.EDU ????
Thank you gentlemen, TB

Use ExpressSCH to open/modify .SCH files. Find it here: http://www.expresspcb.com/ExpressPCBHtm/Download.htm . However, that is just a schematic, not PCB layout.

TGSL is basically a 90 deg DISC range, but I think the actual range of metals depends on the TX frequency as well as the phase-shift range. TGSL in DISC mode can detect all metals beyond iron I think.

No greater range disc modes available yet that I know of. I designed a circuit for 180 DISC but it is not centered correctly yet -- would require more parts or complete different phase setup with coils (or design change).

Eduardos TGSL will have same discrim range as all the others.

Regards,

-SB

[turtlebowl]

EDU.SCH viewer/ Program ??

Hey guys. I have several times downloaded giftpaks etc and been unable to open them.
I want to make Eduardo's PCB but need the program to open his files. I currently use the Sprint 5 software.
Can someone dirrect me to a program that opens .SCH files??

Also while I am asking Questions........... is the TSGL a D-120 disc range?? D-90??
Are any versions D-180?? What range is Eduardos TSGL.EDU ????
Thank you gentlemen, TB

[simonbaker]

as previously stated, I built TGS, which worked ,but I had trouble with notch filter. I was going to build TGSL, but I settled on TGSL edu, I now get 30 cm depth. I went out hunting a 100 year old high school playfield and found a canadian quarter and some pennies. To my amazement, I found razor sharp discrimination between silver and aluminum. complete discrimination of large steel, but strangely I was hitting old magnetic sensitive beer bottlecaps. Here are some pics of my latest vacuum formed coils. If it is helpful to anyone, I found that you need to get the abs hot enough that its sagging almost to the bottom of the oven, carefully watch it! then you place the frame on the vacuum box, and you will here the rPMs of the shopvac go up, and you will get good detail on your coil shell. On nulling the coil, I hold the top coil while watching the oscilloscope, then drop dollar store glue gun glue on coil points, I then use dollar store $1. epoxy to secure coils further. Then use 24 hr epoxy to fill the coilshell with no movement.
Finally I got a good discriminating reliable detector. I searched the TSGL posts. and saw that the original Tesoro patent allowed bottlecaps? anyone???

Excellent job!

Yes, rusty bottlecaps seem to be able to fool Tesoro, maybe all, MDs. I don't know why.

-SB

[Wiltran]

TGS

as previously stated, I built TGS, which worked ,but I had trouble with notch filter. I was going to build TGSL, but I settled on TGSL edu, I now get 30 cm depth. I went out hunting a 100 year old high school playfield and found a canadian quarter and some pennies. To my amazement, I found razor sharp discrimination between silver and aluminum. complete discrimination of large steel, but strangely I was hitting old magnetic sensitive beer bottlecaps. Here are some pics of my latest vacuum formed coils. If it is helpful to anyone, I found that you need to get the abs hot enough that its sagging almost to the bottom of the oven, carefully watch it! then you place the frame on the vacuum box, and you will here the rPMs of the shopvac go up, and you will get good detail on your coil shell. On nulling the coil, I hold the top coil while watching the oscilloscope, then drop dollar store glue gun glue on coil points, I then use dollar store $1. epoxy to secure coils further. Then use 24 hr epoxy to fill the coilshell with no movement.
Finally I got a good discriminating reliable detector. I searched the TSGL posts. and saw that the original Tesoro patent allowed bottlecaps? anyone???

[simonbaker]

Read this ->
http://www.maxim-ic.com/app-notes/index.mvp/id/1957

This is the one I use -- note the resistors are not necessary for TGS due to dual supply, just ground the non-inverting input.

-SB

The circuit in Figure 1 satisfies both conditions.

If the circuit has dual supplies, ±3V for example, the two resistors are not necessary and simply grounding the non-inverting terminal is sufficient. Additionally, the non-inverting terminal can be connected to another voltage elsewhere in the circuit that is within the input common-mode voltage range of the device, thereby eliminating the need for the two resistors in Figure 1.


Figure 1. A properly terminated uncommitted op amp. The input common-mode range is satisfied and the output is within the output voltage swing range.

[Qiaozhi]

I assume eduardo's PCB has the resistors (haven't checked myself). Just wondering if anyone else gets rid of them (I do on my PCBs, but doesn't mean it's good), and if it is good practice to use the simpler way to tie off the unused op amp.

If so, it would give eduardo a little more space to work with on the PCB, and a simpler PCB to build. Just a suggestion.

-SB

Read this ->

http://www.maxim-ic.com/app-notes/index.mvp/id/1957

[Jerry]

I was taught not to leave any unterminated inputs on multiple device chips but that was a long time ago

Jerry

[simonbaker]

Sorry about that.. I wasn't focused on that part of the circuit at all so didn't even look at it!
Don

I assume eduardo's PCB has the resistors (haven't checked myself). Just wondering if anyone else gets rid of them (I do on my PCBs, but doesn't mean it's good), and if it is good practice to use the simpler way to tie off the unused op amp.

If so, it would give eduardo a little more space to work with on the PCB, and a simpler PCB to build. Just a suggestion.

-SB