IGSL

[Hyena]

IRSL

Hi, I want to share some mods I did in autumn to IGSL.

1) Disc channel can also work in All metal mode.
2) Pinpointer with VCO

Ad1) in All metal mode - Disc is in all metal mode With standard Acceptance simulatenousely I can pick up more stuff from greater depth and I still have some Discrimination, because if target is clearly ferrous, I will get mixed tone. If it is precious or small/deep ferous, only high tone is present and I dig it...

Ad2) It is Pinpoint channel taken over from Tesoro Royal Sabre. It has non motion pinpointer/Auto retune switch and fast retune button. So I would call it IRSL. I also added VCO from LM373 datasheet.

I tried channel from bandido II but it worked only for coils with phase shift 200° and residual voltage after first Rx op amp higher then 500mV. Maybe some mistake, I do not know... Anyway I left Threshold from bandido also on board...
Switching between modes is provided by 4 Pole / 3 Positions rotary switch like this one: https://ae01.alicdn.com/kf/HTB17ZwUQ...Xq6xXFXXXr.jpg

So I have:
1) Disc/Accept as usual
2) Pinpointer
3) All metal Disc/standard Acceptance

A attached schematics. There are pin swap mods for Acceptance channel and GEB channel against original design - as is mentioned in this thread on several places. I also changed LF351 for LM833 to have both channels the same. PCB for pinpoint does not exist, I did it on prototype board as you can see on pics. There is add on board for this channel and another one for VDI. Now it consumes about 100mA which is quite a lot. I would to draw SMD board for pinpointer and VDI at once with TL064 and I will change LF347 in Acceptance channel to TL064. One half of LM393 is used for GEB of Pinpointer and other half for VCO. Capacitor drives frequencies. 22nF is for 200-400hZ (15nF is 240 - 500Hz and so on...), which I found as most pleasant. There is spare op amp on LF357 and I did not grounded inputs as is often mentioned in datasheets for op amps. This and few more things I want to correct on SMD board. Case has a lot of buttons, some of them can be reduced by CD4053 maybe... Do you have any other recommendations which I should implement?

Off course, you can add this also on any TGSL...

I will shoot some video in next few days. I never had MD with Pinpointer so I do not know if it work as it should

Anyone interested?






IRSL_v1.02.zip

[Davor]

I'll try a common "all metal reference" for discrimination. So far the slower motion and symmetrical compression served me well in lieu of a proper pinpoint mode, but I'll be interested in a VCO mod.
Although TL064 draw a little current, their 1/f noise is bad, so try them and compare them with a more silent parts. Preamp should fix the noise in motion mode, but I'm not sure about non-motion.
I'm also sorry for not being here until recently - I had a bigger fish to fry.

BTW, a zip file won't open.

[Hyena]

Hmm, noise can generate problems since I have stereo potentiometer for sense.

Strange, that zip is really broken. Try again: IRSL_v1.02.zip

[Davor]

It works now, thanks.
Your PP solution looks simple and straightforward. Just have in mind that a servo is only as good as its 1/f performance.

There is a big step forward in IGSL performance with symmetrical compression. A single diode per amplifier was perhaps OK in 741 era, but not today. I removed the diodes in the first stages of channel amplifiers, and placed them in anti-parallel with the diodes in the second stages, where I removed 22n diodes. So in fact you have a place to put those diodes from the first stages. The result is a crisp response with superb recovery speed, and almost a pinpoint response near the target.

There are a few more mods. The big step forward is a proportional volume mod. It steel needs a small improvement in form of a threshold control, which is in Whites' detectors usually called a "tune". I expect considerably more depth with "tune" in function, as small signals may fail to produce any response now. I'm looking forward to implement these few small improvements soon, and when I test them I'll put an updated schematic.

[Hyena]

OK, I have one spare unit only with pin swap mods. I will try symetrical compression and looking forward to your proportional volume

[Basti1983]

Which files are the newest that working for sure?

[BKY1337]

This here is the Version from Silverdog.: igsl TGSL coils.rar

You need Sprint-Layout from Abacom to open it. Or Sprint - Layout viewer (free).
Its for Tesoro Coils.

There is also another Version for Minelab coils.

[Basti1983]

And that is the version that have the different sound for iron and non iron?

[Basti1983]

Has somebbody a board and maye a pick list from reichelt.de

[BKY1337]

Yes. Everything in One Layout. You could also make the normal tgsl and add the 2tone Board, but this Version is better.
You can use the build document from the tgsl edu for the Coils.

I don't have a Board from the igsl.

[Basti1983]

Hello guys i am building the pcb from Silverdog with the Musketeer coil and i have some question about the used parts. Do i need the LM833 N or LM833 P? And which 4066 i need because it gives the MOS 4066 and 74HC 4066 and the CD4066.

[Basti1983]

Ok i found it by myself. Is it possible to use a 250ohm pot for the 220ohm pot

[kt315]

And which 4066 i need

just for fun )))) https://images.gr-assets.com/books/1...l/29547404.jpg

[dbanner]

That's insulting. Why not send us your copy for free. Just for fun.

[Basti1983]

Yeah really helpful not everybody knows everything.