Author Topic: DIY or make your own Metal Detector kits (Read 7124 times)

6666 · « **Reply #50 on:** October 10, 2011, 23:38 »

Hi Adam
well the quick way out is go with a BH, just put in some batteries and off you go.

the easiest kit to make would be the surf PI, its a beep and dig machine.
the coil is made from enamel wire, tight wound coil , 23cm dia, 20turns, .5mm swg
IF you construct it correctly and dont have any faulty components
all you need is a multimeter to make one voltage adjustment
and it should work, of course it needs a box and batteries and rod and arm rest etc
cheers
6666

6666 · « **Reply #51 on:** October 11, 2011, 10:10 »

I will try a picture here, it shows a surf PI in a box and the coil

Adam · « **Reply #52 on:** October 11, 2011, 22:44 »

Thanks for the reply 6666, I do love soldering kits together though, if something goes wrong other than voltage or current flow it is usually when my talent stops.

I think I could handle that coil easily enough. Is it possible to do a DD coil?

Could you be so kind to send me a link to the component kit?

6666 · « **Reply #53 on:** October 14, 2011, 11:23 »

Here you go

http://www.silverdog.co.uk/

The surf PI is a beep and dig pulse induction machine, it only uses a single coil not DD
it is a very simple cct to make,

also have a look at post 9,10, 22 of this thread
cheers

gcause · « **Reply #54 on:** October 25, 2011, 23:16 »

Hi Mr6666 and Sido,

Excellent work on the SurfPI and Barracuda.

I will be getting the Barracuda kit for my PI project and would be keen to share results with you both.

Here is my efforts so far:

http://golddetecting.4umer.net/t6394-grant-s-diy-pi-detector

Regards,

Grant

Rwork · « **Reply #55 on:** October 26, 2011, 06:34 »

Welcome Grant,good to see another member who is interested in the technical side of detecting.

6666 · « **Reply #56 on:** October 28, 2011, 15:21 »

Hi Grant
the Barra seems to have a slight edge over the surf
I have built mine and it works ok
need to box it, and make a better coil housing.
watch out for the wire strap you have to insert
there maybe two, dont have it in front of me right now
please give a report when up and running

gcause · « **Reply #57 on:** November 04, 2011, 09:54 »

Hi 6666,

Please forgive the obvious question but "What wire strap?".

Also what coil do you use on the barra DD, mono, etc. No of turns, wire guage, etc?

I have read the Coil Basics and Fast Coil for PI detectors PDF's so have an idea on construction techniques and have built my own coil winding jig.

Will commercial coils work with the Barra I have a Coiltek 24x12 UFO mono coil I would like to try with it?

Regards,

Grant

6666 · « **Reply #58 on:** November 04, 2011, 17:58 »

Hi
I was actually thinking of the wire strap on the surf pi
but there is also a wire strap that goes around the "C" on the Barra as well
helps to hold it down to the board.

re the coil I have made several for the barra, MONO ONLY.

re that mono coil if its around 400uH - 450uH it may work

I will have to get my note book out for the specs on the bara coil
the specs say 453uH, 1.4R with a 330R damping resistor
people have made it with various values around the 350uH -450uH mark
and it works ok, to get maximum performance you need to trim the
damping R, check out post 51.

gcause · « **Reply #59 on:** November 05, 2011, 17:50 »

Hi 6666,

Thanks for that.

I see, you mean the wire strap to hold the capaciitor to the board, so its not part of the circuit just a strap to hold it down.

I bought the coil second hand so I am not sure on the specs of the 24x12 UFO mono coil and they dont seem to supply them on their website.

I dont have an LC meter but I do have a multimeter so I should be able to measure resistance at least.

Is there any other way to get the ohm value for the coil?

Regards,

Grant

6666 · « **Reply #60 on:** November 05, 2011, 21:31 »

If you have a multimeter, the good thing about the silverdog kits is
the "r's" come labelled, I suggest you test all the r and c's before you solder them in the pcb
the kit comes with small trim pots, some of the trim pots need to be replaced with full size pots
so you can adjust them from out side the case.
the one real voltage adjustment you need to make is adjust the voltage on pin 6 of U2 ne5534 to zero volts

also some people have reported some instability with Q5 mpf102, leave it out of cct.
and make sure you put the 2222 in the right way, check the legs

the bara cct says a coil about 450uh
a coil 200mm dia
with .43mm enamel wire
and 27t should get you close to test

what enamel wire do you have ?

gcause · « **Reply #61 on:** November 06, 2011, 13:02 »

Hi 6666,

>with .43mm enamel wire
> what enamel wire do you have ?

0.5mm would be closest I could get to this.

Regards,

Grant

6666 · « **Reply #62 on:** November 06, 2011, 16:14 »

.5 is getting on the large size and the resistance is starting to get low
it should work ok, dont go any bigger
so for 452 uH , 200 mm dia , .5mm, 28 turns will be close
tightly bind the windings.

cheers

gcause · « **Reply #63 on:** November 19, 2011, 15:23 »

My Barracuda and SurfPI Silverdog kits arrived today. Boards and components.

I ordered two of each in case I stuff it up and if I dont it will allow me to experiment with one.

Need a high def photo of the completed boards so I can see the orientation of the components on the PCB as I dont want to stuff it up by putting a component in the wrong way around.

I have asked Silverdog to e-mail this to me.

gcause · « **Reply #64 on:** November 20, 2011, 10:45 »

Hi Mr 6666,

> the kit comes with small trim pots, some of the trim pots need to be replaced with full size pots

Which trim pots should I replace?

Regards,

Grant

6666 · « **Reply #65 on:** November 21, 2011, 14:47 »

Hi you got both kits did you
will try and build the surf pi first its a little easier
build the +- power supply first

vol delay and threshold should be external pots they are the most used
the silk screen should have the orientation of the components
just watch out for the 2222 depends on which case its in
the caps are all marked but double check you are putting in the right value
good luck
6666

gcause · « **Reply #66 on:** November 23, 2011, 08:31 »

Hi 6666,

Thank you for that.

I had already started the Baracuda and have it all together now.

The kit came with the tin pot version of the 2222 so I followed the layout on the PCB for its orientation as it seemed to be correct.

I didnt change the trim pots for full size pots but left the legs long on these on the underside of the PCB so I could add these later.

One of these trimpots is marked as the delay and there is a separate full size 10k pot for the threashold, but the other trimpot doesnt say what it is for could you please advise what this is?

I am assuming it is for tuning the coil to the right frequency.

I saw mention on the GeoTech forums that you could use any voltage between 5v and 12v to power the circuit so I am using a regulated power supply circuit connected to a rechargable 12v battery being regulated down to a constant 9v. I can change this to any voltage lower than the supply.

Unfortunately the baracuda circuit doesnt work for me. The circuit fires up and gives a buzz in the earphones as it powers up but it doesnt detect metal of any kind.

I didnt have a valid coil though. I just used one I had made earlier which only had 7 windings as a quick test.

I also tried it with a commercial mono coil and couldnt get it to work with that.

I then tried a DD coil I had built with 40 windings on each coil also and that didnt work either.

Each time I adjusted the unnamed trimpot until I got a loud buzzing noise in the earphones and then moved it back until it was right at the edge of doing this. But it never detected metal of any kind no matter what I tried.

I guess I was just too keen to try it out having seen some people suggest their quick and dirty coils had worked to test with.

I will go wind a valid coil 452uh as you suggested earlier with 28 windings and then try again.

The circuit is running extremely hot and it is giving off a faint buzzing noise even when not connected to the audio. Had to put a large heatsink on the main transistor and even then it was hot. The rest of the circuit is running cold.

I have a scope and a multimeter but I am not sure what to check for with these.

Any advice on getting this working would be greatly appreciated.

Regards,

Grant

6666 · « **Reply #67 on:** November 24, 2011, 09:58 »

If you got a 2222 in the metal can the tab should match the emitter on the silkscreen

wind a real coil as per specs, there should be no heat coming from the fet.
hopefully you have not damaged it.

the r39 25k trimpot at the top of the board is the offset
put your multimeter between gnd and pin 6 of U2 and adjust to zero volts

you say you are useing headphones use the peizo buzzer to satrt with you wont get much audio
from headphones

6666 · « **Reply #68 on:** November 24, 2011, 13:12 »

I also forgot to mention
when you are testing to completely keep your coil far away from any other metal

gcause · « **Reply #69 on:** November 26, 2011, 17:24 »

Hi 6666,

I wound a new coil but no joy, it still doesnt work.

I have posted pictures on the GeoTech forum, here asking for help:

http://www.geotech1.com/forums/showthread.php?p=140130&posted=1#post140130

I tried the voltage setting and was able to get it to go back to zero volts but no joy either.

Tried various delay settings and no joy.

Would appreciate any further suggestions.

Regards,

Grant

6666 · « **Reply #70 on:** November 27, 2011, 17:39 »

Grant if you cannot get it to go you can send it to me with return postage and I can have a look at it for you

also be care full when people quote parts to you to check
there are a couple of different ccts abouts

sido · « **Reply #71 on:** December 01, 2011, 15:31 »

Great to see another interested member in building their own detector (gcause)

6666, have you tried the VDI project?.... I can see that i might be able to adapt that to my Gsnoop and would make a nice addition with having numbers displayed, instead of relying solely on tones. A back light version of the lcd display will be handy for night tecting

From what i have read, it can be adapted to most VLF's.....

Sido HH

6666 · « **Reply #72 on:** December 02, 2011, 10:19 »

Hi Sido welcome back
no I have not tried the vdi project YET
but its on my list of things to do
I just got a whites V3i so been playing with that in my spare time
there have been some good projects popping up lately
cheers
6666

6666 · « **Reply #73 on:** December 02, 2011, 11:41 »

All
a mistake in the silkscreen of the Silver dog Surf PI ver 1.2 pcb has just been found
R18 and R22 are transposed on the silk screen remove them and re solder
them correctly sensitivity should increase.

6666 · « **Reply #74 on:** December 03, 2011, 10:28 »

The silk screen should look like this for Surf PI.