complete project

[mschmahl]

Thanks again for the schematic tinkerer.
What batteries should i use? I can buy different one.
For the coil-cable i have AWG12 for TX and BU. It is 3,5mm with isolation (800V rated) 80 meters long. For Rx i have AWG22 http://www.digikey.de/product-detail...B-100-ND/16146 30,5 meter.

Greetings from saxony

[Tinkerer]

Do you have a schematic for DESIGNPARK for RX? Can you share it?For the parallel Capacitor to C6 i use Sockets, so we can try different values. For what Inductance is the LC tank made now? 300uH or 350uH?I made the changes for TX now(R3 3W 2OHM, Switch, Socket for C1, R1 one side to 0V).Thanks a lot tinkerer!

Thank you for the help with the schematics.

OK, the purpose of R3 is to slow down the inrush current to the drive capacitor bank.

For your purpose, small silver coins at 50cm, we want a powerful TX drive. We start with about 1.5A coil current, but we leave the possibility to increase to 3A coil current.

Since you want to use small batteries, we limit the TX power consumption at about 50mA for 1.5A coil current.

My hard drive crashed a few days ago. There are some draft schematics left. I send you one of these.
Warning: this is a work in progress. The schematic may contain errors. I give it as a base to work from.

[mahavir]

Hi friend
I'm from India, I want to make gold metal detector but I confuse which is better so plz help me..

http://www.geotech1.com/cgi-bin/page...e=projects.dat

thank you..!!

[mschmahl]

Do you have a schematic for DESIGNPARK for RX? Can you share it?
For the parallel Capacitor to C6 i use Sockets, so we can try different values. For what Inductance is the LC tank made now? 300uH or 350uH?
I made the changes for TX now(R3 3W 2OHM, Switch, Socket for C1, R1 one side to 0V).
Thanks a lot tinkerer!

[Tinkerer]

The tinkerer_SB PSU&TX side is ready. The pcb is very ugly because of my testboard, but all voltages are correct. There are two confusions on the PSU, so i have made a picture with changes how i have built it. The next step is building the RX-part.
[ATTACH]23283[/ATTACH]

Thank you for the feedback. Your corrections are correct. I see that you use DESIGNSPARK, so I add the schematic.

It is good to add a space for a second capacitor parallel to C6, as it makes easy to obtain precise capacitance for the LC tank circuit in case you want to change to a coil with different inductance.

[mschmahl]

The tinkerer_SB PSU&TX side is ready. The pcb is very ugly because of my testboard, but all voltages are correct. There are two confusions on the PSU, so i have made a picture with changes how i have built it. The next step is building the RX-part.

[mschmahl]

Yes, this is right. The outer diameter is not critical (50 or 52 cm no problem at all), because i will glue it on a plate made of "plexiglass"(don´t know the english word) and than coat it.
I want to use 1,5V AA batteries (2x4 batteries for the 2x6Volt in your schematic). But i could be more or 1,2 V rechargeable if it is better. Targets are the thin silver and big silver coins. If the gold coin isn´t in the area where the tinkerer work it´s no problem, because we don´t have a lot here.

[Tinkerer]

Tinkerer, thanks for the pictures http://www.geotech1.com/forums/showt...267#post166267.
Now all part´s for the Tinkerer_SB have arrived me. So I can built it.

Could you confirm or correct for me:

You want to build a 50cm outer diameter coil? About 48 inner diameter coil?

8AA batteries?

Targets TC, 10 to 200us = thin silver and gold coins at 40 to 50cm depth?

[mschmahl]

Tinkerer, thanks for the pictures http://www.geotech1.com/forums/showt...267#post166267.
Now all part´s for the Tinkerer_SB have arrived me. So I can built it.

[mschmahl]

The first parts have arrived me. So i can start with building soon.
@ tinkerer
Do i need some additional parts for the easy ground balance or is it done in software?
Do you have some pictures of coilbuilding? Especially from RX?
Thank´s a lot

Greetings from saxony

[Pete the Builder]

25cm coil sounds near-perfect, Tink. Bring on the photos!

I also prefer using separate threads from here on. We can divide our time more efficiently, perhaps!

Cheers,
PtB

[Tinkerer]

So it will be a 50 cm Coil. I will built it similar to the tgsl-coil http://www.geotech1.com/forums/showt...887#post163887 here. Than coating it with fiberglass. For shielding: Do i have to shield the TX, RX and BU bundle seperately? What is with spacing between each bundle an shield? Or should i use graphit-paint on the completed coil before coating?

Remember that you will use a #12 or #14 wire for TX and BU. This will be a bit stiff to wind on a fragile core. It will need tying with string.

Graphite paint is OK. Make sure you get a good connection from graphite to ground. The spacing is not critical, as the TINKERERS is not sensitive to inter wire and wire to shield capacitance.

All leads coming and leaving the coils must be twisted to keep balance.

Test the coil induction balance before applying any glue. You should get about 25 to 50mV at the input of the pre-amp.

When You are ready for fine tuning the inductance balance I will give you some tips for it.

[mschmahl]

So it will be a 50 cm Coil. I will built it similar to the tgsl-coil http://www.geotech1.com/forums/showt...887#post163887 here. Than coating it with fiberglass. For shielding: Do i have to shield the TX, RX and BU bundle seperately? What is with spacing between each bundle an shield? Or should i use graphit-paint on the completed coil before coating?

[Tinkerer]

Hello Tinkerer,
I have coil-housing in 25 cm outer diameter. But i think, such a little coil does not go to 50-60 cm deep Silvercoins. So i think 40 or 50 cm should be better for my need´s. Or is it not so?

I would use a 50cm coil to search for these deep silver coins. If you do not have a housing, you can use a styrofoam base or just fiberglass the coil after precise inductance balancing.

[mschmahl]

Hello Tinkerer,
I have coil-housing in 25 cm outer diameter. But i think, such a little coil does not go to 50-60 cm deep Silvercoins. So i think 40 or 50 cm should be better for my need´s. Or is it not so?