IGSL

[Davor]

Probably I will.
There is a reason why "Iron sens" seem to work fine: GEB channel. Conditions for a FE channel for small target signal are set by Fe GEB channel only, since the Fe Disc channel comparator is constantly on. It will make more sense when it starts behaving in accordance to the Iron sens setting, you'll see.

[der_fisherman]

I've found one mistake in "Ferrous channel" and it will not be too easy to fix on the existing board. It is related to the inverting/noninverting inputs of comparators U7d and U4c. They both need to be reversed for correct operation, and it will not be trivial

Let me explain. Comparators contained in U4 clock the 4066 switches by phases set by the preceding circuitry. Resulting signal is amplified in respective channels and fed to U7 comparators that form analog AND circuitry. For non-ferrous detection GB AND non-ferrous disc signal make for non-ferrous detection. To make them less hectic there is a "sens" potentiometer control that actually provides a threshold below which there is no detection and it works fine for non-ferrous channel ... but not for the ferrous discrimination channel.

It becomes active when there is a positive signal on ferrous GEB channel, but also for 0V on ferrous disc channel - which makes no sense. It is supposed to be active only for negative signal in ferrous disc. channel.

It can be kinda corrected by "Nonferrous accepting level" potentiometer, but it is level dependent and gives oddly overlapping results at low target response levels. I guess lots of chatter too.

I'd propose a solution with exchanging pins 8 and 9 of U4c and pins 10 and 11 of U7d. It would make "Iron sens" control behave as expected and overall behaviour more predictable. It would reverse phase of the ferrous disc. channel, and it will make discrimination comparators work for positive signals, and it will make "Nonferrous accepting level" potentiometer actually do its job.

In my builds I'll have to make it "ikebana" style by first extracting the existing sockets, doing some nasty acrobatics with wires and it should work correct then. Too bad I did not notice it before the sockets got welded Maybe I'll better cut the lines on PCB and rewire everything there - seem like a bit less trouble.

here is a picture of the proposed changes:

If you are right, fantastic work!!! I will be following this very carefully and will probably eventually make the changes as my IGSL is still erratic (though I really don't have the needed knowledge on the electronics of such MDs).

May I suggest that instead of removing the soldered in socket, that you simply take out the chip, bend out the two legs in question on the chip, press it into a new socket to mount in the old socket. After first adding two short wires from each bent out pin to the correct socket pin, on the extra socket.....

I hope that I have written it clearly enough, but if you have any questions, please just ask.

I have used this to fix problems on digital circuits more than a few times, and I have stabilised the extra socket with hot glue once the functionality has been proved.

That way, no changes are made to the PCB, TILL it has been proved that the changes are good and valid. then we should make sure that Silverdog gets the changes made and the rev. level updated.

Of course mechanically adding an extra socket, is probably not good in the longterm as any small shocks could loosen either the chip or the extra socket. High quality sockets will of course reduce this danger.....

Again, many thanks for your work, and do please update us with regard to your test results etc... we are ALL here very, very interested......

As I believe Ivconic himself said at some point, this detector, although mainly thought about and made/set up by him, is a work in progress with many inputting ideas and changes......

Regards

Andy

[ivconic]

...
As I believe Ivconic himself said at some point, this detector, although mainly thought about and made/set up by him, is a work in progress with many inputting ideas and changes......

Correct, that's why i shared it here. One man band is not good thing.
Several people are always much smarter and more capable than single one.
Davor is having interesting ideas and i think he can make few steps forward with IGSL.
Cheers!

[der_fisherman]

Correct, that's why i shared it here. One man band is not good thing.
Several people are always much smarter and more capable than single one.
Davor is having interesting ideas and i think he can make few steps forward with IGSL.
Cheers!

Exactly right!
Also, I am sure that with such great people as yourself, this will eventually be a great detector for the many who will build it.
I am happy to wait and learn.
Many thanks to everyone doing the hard work here.

Regards

Andy

[der_fisherman]

If you are right, fantastic work!!! I will be following this very carefully and will probably eventually make the changes as my IGSL is still erratic (though I really don't have the needed knowledge on the electronics of such MDs).

May I suggest that instead of removing the soldered in socket, that you simply take out the chip, bend out the two legs in question on the chip, press it into a new socket to mount in the old socket. After first adding two short wires from each bent out pin to the correct socket pin, on the extra socket.....

I hope that I have written it clearly enough, but if you have any questions, please just ask.

I have used this to fix problems on digital circuits more than a few times, and I have stabilised the extra socket with hot glue once the functionality has been proved.

That way, no changes are made to the PCB, TILL it has been proved that the changes are good and valid. then we should make sure that Silverdog gets the changes made and the rev. level updated.

Of course mechanically adding an extra socket, is probably not good in the longterm as any small shocks could loosen either the chip or the extra socket. High quality sockets will of course reduce this danger.....

Again, many thanks for your work, and do please update us with regard to your test results etc... we are ALL here very, very interested......

As I believe Ivconic himself said at some point, this detector, although mainly thought about and made/set up by him, is a work in progress with many inputting ideas and changes......

Regards

Andy

what I forgot to mention, if you feel the need to remove the original socket, is to buy "wirewrap" sockets, they have very long legs, and insulate both the legs to be crossed over and then carefully bend them to their new position, solder in the socket so it sits about 1 cm above the pcb. This is mechanically almost as good as the original socket on the board once all legs are soldered in. Solder both sides, that is top and bottom, for extra strength and rigidity.

here is a picture of one type or such a socket, they belong in every workshop....

Regards

Andy

[Davor]

Yeah, this could work. Trouble is that the changes affect two comparator chips so it is a double trouble. Sockets are very close with price to the chip itself, and it is only for the sake of convenience that I used them in the first place. I'll see what changes it will require on a PCB to make this work. Maybe I'll just do some knitting with the chips' pins and force them into sockets - these are adjacent pins in both cases.
I also bought a stereo pot for this "Sens" actually threshold control. I figured that, although a useful setup to have, it is not needed to be separated. There is much bigger difference in signal strength viz. depth, thrash, etc. than it is meaningful in setting channels differently. I'll also use a stereo pot for "Tresh." actually sound level control.
I thought of common GEB control, but so far I have no idea whether I need it set outside or not. As I intend to use it also on beaches, most probably I'll figure something out. There is an odd effect that rotates phase response when Rx input is loaded, and I'll try some trial and error with that

[der_fisherman]

You are forgetting the cost if something goes wrong when removing, a PCB track gets ripped or something. Sockets are so cheap nowadays....

[Davor]

Nope, just about the same here. But they ARE convenient.
BTW, I got a batch of sockets that are incredibly difficult to solder - they are not wetting at all. It happens only about 4 or 5 seconds after I apply heat. No other component ever behaved like that on me. OK, maybe aluminum wire but that is expected.

[ivconic]

Nope, just about the same here. But they ARE convenient.
BTW, I got a batch of sockets that are incredibly difficult to solder - they are not wetting at all. It happens only about 4 or 5 seconds after I apply heat. No other component ever behaved like that on me. OK, maybe aluminum wire but that is expected.

I know what are you talking about!
Those are worst quality, made in China.
I am having same problems from time to time.
My Weller is ~40W and i am struggling sometimes to solder such bad alloys.
You can try sharp knife and carefully scrape oxidation with it.
That can help a bit.

[der_fisherman]

Nope, just about the same here. But they ARE convenient.
BTW, I got a batch of sockets that are incredibly difficult to solder - they are not wetting at all. It happens only about 4 or 5 seconds after I apply heat. No other component ever behaved like that on me. OK, maybe aluminum wire but that is expected.

Try cleaning the pins with alcohol, or even with very fine wet and dry.....tin before usage.
If that doesn't help, simply throw them in the rubbish, the last thing you want is a dry joint later.....

[Davor]

I have 50W Weller magnastat and it works purrrfect. Ticks like a clock. But these sockets are a bit different.

I scratch them a bit and heat them for ~5 seconds so they usually give in. Then I inspect them and redo if suspicious. If anything goes wrong it will be for these $%#/&$% sockets

Their pins are shiny, sharp, and not pliable at all. Horror. It was late Saturday when I bought them. Should have waited till Monday.

[Jerry]

Nope, just about the same here. But they ARE convenient.
BTW, I got a batch of sockets that are incredibly difficult to solder - they are not wetting at all. It happens only about 4 or 5 seconds after I apply heat. No other component ever behaved like that on me. OK, maybe aluminum wire but that is expected.

I ran into something similar a few years ago. It seemed like the solder wanted to just roll off of everything and you almost needed a blow torch to get things hot enough to make the solder flow.

As it turned out, it was the solder I was using! I had bought a one pound roll at a swap fest really cheap. That is exactly what it was...... Really Cheap Junk!

Using a better quality solder solved my problem. Don't know what you are using but it may be something to look at.

Jerry

[Davor]

I could try another roll that I have, fluitin or something, but point is that everything else wets instantly with this one, flux is not burnt, smells as it should... anyway, this is off topic stuff, so lets drop it. Low quality of nowadays parts may require a topic of its own.

[Davor]

Back to the topic...

I made a LTspice simulation of a whole disc + GEB + comparators + audio stage
It may require some tweaking in LTspice control panel because of the comparators that are famous for sloooooow convergence, but here you go, I made some changes to the original setup, but they are in circles, so have fun.

I think I've found the main source of chatter, and I wonder if someone else will get to the same conclusion. If someone wishes to know what is what here, just ask

[Davor]

I am still populating my IGSL and due to some family obligations I'll have to stop for the weekend

Anyway, I think I found the main source of chatter and odd and shortened responses. It is the combination of LPF and compression that in effect shift phases between GEB and Disc channels. Otherwise they are in phase or in counterphase, but these shifts make things more interesting. I'd say signal is overfilterred, and I may come up to some bullet proofgain stage that behaves.

Keep tuned...