IGSL

[simonbaker]

Nice App Jerry.

It shows that, say 20kHz, currents are flowing in the top 0.5mm of wire surface. (That would be both sides')


So easily, in that case, the whole cross section of a 0.5mm wire is carrying ac currents. Full current carrying capacity of the wire - on balance, no skin effect.


But at 2GHz currents are in only the top 1.7 microns of depth.. The reason silver plate is used. Full-on skin effect

Steve

Another handy calculator yes! Would have saved me much head scratching.

Bear in mind that the "proximity effect" applies to bundles of wires, such as our coils -- the diameter there is probably 5 mm or more. However, I don't know of a calculation for it.

Regards,

-SB

[Comp]

"...I am also still searching for a plastic tube for the lower part of my stem, nothing I have found fits anywhere near......"

You are not the only one!
I am searching for such thing also.
Ordinary plastic tube/pipe will not do. Must be strong and robust plastic.
I tried to use some plastic pipes and those are deflecting on each coil swing. Annoying!
So it must be made from pretty robust plastic and with fat walls.
Haven't founded such thing yet...

Hiya!! I am using a paint roller extendable tube from B&Q, internal diameter of the bottom rod is 20mm, so have fitted a length of 20mm plastic electric conduit piping on the bottom, it is fairly thin walled/flexible, but I have epoxied a length of snug fitting Bamboo cane inside,... it is now stiff, and light,....... and seems fine,.......

(not sure what the wife will support the runner beans on next year, though!!!! LOL!)

Cheers, Fred

[SVEN1]

Battery Power

Thinking about running two 9 volt alkaline batteries in series (18 volts) to conserve space.
I know the LM7808 can handle the extra voltage. Would I need to add a heatsink to the Lm7808 to dissipate any excess heat that might be produced?

What kind of operating time might I expect using two 9 volt batteries vs. eight AA batteries or eight AAA batteries?

Or....might be better to use three 9 volt batteries using a serial/parallel connection?

[Amalio]

Thinking about running two 9 volt alkaline batteries in series (18 volts) to conserve space.
I know the LM7808 can handle the extra voltage. Would I need to add a heatsink to the Lm7808 to dissipate any excess heat that might be produced?

What kind of operating time might I expect using two 9 volt batteries vs. eight AA batteries or eight AAA batteries?

Or....might be better to use three 9 volt batteries using a serial/parallel connection?

7808 lm prepared to 35v 1.5a.

I think without problems in three occiones

regards

[kliner]

Sven
I think the average 9 volt battery is rated at about 200mah, the IGSL takes about 70mah so you're not going to get very long (2hours with a little safety margin)
A rechargable NIMH AA is around 2000-2600 mah, an AAA around 800-1000.
I use a 3s Lipo, small light, you just need a special charger and to take a little care, thats what they use in the XP Deus.
I get mine here http://www.giantcod.co.uk/gens-1600m...-p-406711.html

[MAURICE]

IGSL shematic for Diptrace

HI to members of forum.
In my first entry I have now double checked my schematic. The source from pg 37,with the suggested value changes for stability by Ivonic. Schematic was correct but Q8 had incorrect pattern attached.Have now amended.Here is PCB file included.The board is a little large but I have tried to keep it as neat as possible. I work in more classic style using 2mm pads , more suited to beginner to intermediate constructors.
Regards Maurice

[Jerry]

Thinking about running two 9 volt alkaline batteries in series (18 volts) to conserve space.
I know the LM7808 can handle the extra voltage. Would I need to add a heatsink to the Lm7808 to dissipate any excess heat that might be produced?

What kind of operating time might I expect using two 9 volt batteries vs. eight AA batteries or eight AAA batteries?

Or....might be better to use three 9 volt batteries using a serial/parallel connection?

That is what I do on TGSL and it works good and I am happy with the battery life. Cannot comment on the IGSL since I have not built it yet.

Jerry

[golfnut]

Rx coil

I was thinking about the Rx coil. On IGSL

It doesnt make good engineering sense to have the resonatng cap for the Rx coil remotely mounted at the other end of a cable!

There may be some improvement in having the cap co located with the coil.

Then the currents from a return are relatively losslessy contained in the coil cap combination.

The voltage created from theses currents is passed up the wire for amplification.

Anybody try this to see, mine is potted U see.

Steve

[simonbaker]

I was thinking about the Rx coil. On IGSL

It doesnt make good engineering sense to have the resonatng cap for the Rx coil remotely mounted at the other end of a cable!

There may be some improvement in having the cap co located with the coil.

Then the currents from a return are relatively losslessy contained in the coil cap combination.

The voltage created from theses currents is passed up the wire for amplification.

Anybody try this to see, mine is potted U see.

Steve

Let us know what you find out if you try it. My theory has been I want the cap as close to the op amp as possible to short out any voltage spikes or HF noise that the cable may pick up, but I don't know if that's important. It also allows you to use Tesoro coils and be able to tune your circuit for any simple coil. I'm sure there are advantages for putting the cap with the coil too, let's see.

-SB

[bernte_one]

Someone has tested Tesoro search coil 4 pin 10x14 DD?
What are your performance in the field?
Thanks

hello

no but i checked a brand new detech sef 30x38cm 14-18kHz 4 pin for new tesoros last night indoor. not checked in field
null voltage was around 3 volt (if right measured with my multimeter)
when set disc off and sens to max, and threshold to critical it shows a 2euro coin at 50cm in air with sure cracking hard sound but no tone id at this distance
better tone at36cm and lower

i think up to 40cm in air for your tesoro should work

regards

p.s. excelerator 2 coil for minelab does not run on igsl -another phase difference

[bernte_one]

threshold

hello
by the way.. can anynone tell me what the threshold trimmers exactly do and how can i measure a good working point for them
(maybe some testing point for scope or so)

gb trimmer are clear (i have ordered new ferit to set set them)

thx

[der_fisherman]

setting up pots and trimmers on igsl.

hello
by the way.. can anynone tell me what the threshold trimmers exactly do and how can i measure a good working point for them
(maybe some testing point for scope or so)

gb trimmer are clear (i have ordered new ferit to set set them)

thx

I have a feeling that you are in the same position I was in some weeks ago, I asked for setup help, but there was nobody able to supply it......other than saying it was a TGSL x 2 and that should make it simple for me, just read TGSL infos.....which I read all of....
That certainly did not help me as I have never built a TGSL (yet!).......

I have managed to fix a few faults with my own build, 3 chips were faulty and I had wired several pots wrongly, luckily Simon Baker was able to give me a few tips in that area.....thanks Simon.

I have had an idea that I will test in the next couple of days, which is to add DIP switches between the CD4024 outputs and D1 and D2 so that I can swap the connections or even turn one channel off, which should allow me to test and setup the other channel without hearing the first one.....how useful the idea is I am not yet quite sure, we will see.

regards

andy

[bernte_one]

hello fisherman

thx for fast answer
biggest problems are solved
here new video
http://www.youtube.com/watch?v=qhXHHOofZM0

[der_fisherman]

hello fisherman

thx for fast answer
biggest problems are solved
here new video
http://www.youtube.com/watch?v=qhXHHOofZM0

Glad to be of help.
Your machine is stable and very sensitive, just what is needed.
The video sound to picture appears to be delayed and may give some watchers the wrong impression.
Nicely made, thanks for showing it to us all.
Regards
Andy

[anz29]

re

To set ground balance for disc1 and disc2 with two external pot, I need of pumping up and down the coil at same other metal detector??
Sorry for my english, I promise I will become good