TESORO GOLDEN SABRE

[Max]

Hi Ivconic,
I think I've found where was your problem with first cap...

simulating it with 150pF gave me that thing... means that the reactance of capacitor at osc frequency let pass so much signal that 353 goes into saturation in that strange way ... I mean with all that bouncing.

So maybe your wrong cap had a tollerance of more than 50%... very bad one.

Problem is that at out freq and with 100pF signal is perfectly sinusoidal... so, if simulator is right, Ap and me have something parassitistic capacitance of 35-45pF there... cause maybe socket is involved for real... but I think that a socket could not introduce such deviations...

A test we can made is lowering the cap to 50-80pF and see the effects.

Best regards,
Max

[Max]

Hi,
now I think that it's all about reactance of cap + parassistic effects due to board, sockets, wires and also operating frequency that is a bit higher than bought TGS (about 400Hz more from my informations using Ivconic design for coil).

Look below: at 140pF total there you have oscillations like you can see on my traces...

Solution could be reducing the cap value from 100 to 50-60pF to compensate the above things and higher freq.... or much better reducing the feedback resistance to something e.g. 50Kohm instead of 100K.

Now I hope that some proud TGS homwbrewer test that things... one way or another... cause, other things apart, I have to spend my penny now.

Goodnight.

Best regards,
Max

[ivconic]

I have 330 pf installed on TGSL. No, Disc. is not affected at all. Still i can discriminate metals in wide range. For example at "6" Al foils are discriminated completely etc...But i didnt put 10K parallel to disc pot. Actually i put it and see no benefits from it, no matter what other claimed here (with full respect to them - my friends)..
So i gone further experimenting and founded somethin else;
The hell! Why using 100K pot and 10K resistor parallely to pot???? Heck!
Much better and "softer" behavior is when only 10K pot (instead 100k) is used...Try and you will see. Think again; 100K resistance and 10K resistance giving what?? 100*10/100+10 = 9.0xx Koms...So ..??
This is not only theoretical, i done it and for real it is acting much "softer"...
Try it.
Also i put 10pF between 1. and 2. pin on LF353...Not noticeable benefits but also no harm done, so i kept it there.

I am thinking more on this pin 1....well, might be that my osciloscope is to old and unaccurate and showing square instead sinus???
Anyway Disc is working just fine....How come..? Dont have a clue..
Regards!

[ivconic]

Hi Ivconic,
I've tested on the fly... crazy job again... but interesting results.

You are right : at 220pF I got perfect square wave on pin1, with 330pF wave is a bit distorted

About depth: noticed an increase for all metal kinds, both all metal mode and disc, in detecting of copper an aluminium seems also more, less for silver.

The increase for aluminium is from 5-10% , 10% for large items like a beer can...detection is like on some PI with that mod...above 75cm with the 255x137mm coil... on smaller things it's less easy to notice but there is too.

I got good results with 220pf and with 330pf detection is the same but noticed a bit more erratic from time to time... but you have to consider that at now there are some electric interferences around here...so I think it's ok both way... but I will use 220pF.

About disc : is it affected ? I still can reject iron but disc seems affected for good metals though seems small thing to me.

Now my doubt: if signal is square how the disc comparator moves the sampling interval now ? I haven't tested this cause it's late today to make other stuff after all that whisky stuff... but I think that we will lose much of the disc pot effects ...or well... all disc ! The pot have a meaning if the signal is a continuos increasing/decreasing wave ...not two levels only...so, for me, the circuit will go always as with disc pot at min with that mod!

Am I wrong ? Please test that if you can... or Ap, or Geo if you have time for this try.

Kind regards,
Max

At 1. pin of LM393 i get perfect sinus...

[ivconic]

"...Problem is that at out freq and with 100pF signal is perfectly sinusoidal... so, if simulator is right, Ap and me have something parassitistic capacitance of 35-45pF there... cause maybe socket is involved for real... but I think that a socket could not introduce such deviations... "

I am using sort of "test" pcb for this experimenting purposes. It is fully assembled TGSL without housing. Wires from coil are directly soldered to pcb...no sockets here.

[Geo]

Hi. Finally how must be the signal at pin1 of LF353???? square or sinus ???
I have a very good sinus signal that vary about 80 degrees but it don't discriminate. Maybe tommorow to check the capacitor. I think that it must be the last check and then i let it. I have better projects to do than to play with one capacitor if it is 100 or 140 or 220pF.
Regards

[Qiaozhi]

Hi Porkluvr,

I'm afraid you may be correct.

[ivconic]

Wise and funny guys here!?
Quiaozhi i respected you so far. Right now i am reconsidering that.
So many suggestions and tips from you but so less benefits from those.
It is easy to stand aside, ocassionally "drop" some "wide" suggestion and tip...When things oposite your attitude than you showing some pictures and simillar... I understood this place as place when i can talk seriously with people with which i have common interest.If sometimes we dont agree, than i expect to explore problem in details and find spots of disagreement...
If you are tired of taking seriouslu part in here, or dont want to waste your precious time with us here, fine. But please dont act like a wise guy.Sooner or later you'll make mistake...
PorkLuvr's remark about "horse..." wasnt offended me at all. I understood it as a joke. Your post is offending me and i can not take it as a joke.
Anyway like i said, so less benefits from your posts here.Plain academic rethoric. Any "greenhorn" can google arround the .net and find "deep" scientific explanations...blah..blah...and simillar.
But i still havent saw any of your handmades (this doesnt mean that i want to see those here)...
Except few rare members here i can only take seriously Max,Geo and my Dutch friends cose i saw their work in practice,efforts,problematics...
That is what i do respect for real. Plain academic rethorics not!
Further i can take jokes and critics only from them, but not from person with which i do not correlate at all....
Pleas stay away of peaking me further.
Regards!

[ivconic]

Hi. Finally how must be the signal at pin1 of LF353???? square or sinus ???
I have a very good sinus signal that vary about 80 degrees but it don't discriminate. Maybe tommorow to check the capacitor. I think that it must be the last check and then i let it. I have better projects to do than to play with one capacitor if it is 100 or 140 or 220pF.
Regards

If this does matter than i really dont know!? But i straighten up previous signal with 220-330pF and gained clear square. Is there any benefit from that, again i dont know. I do know my TGSL works like a hell, and that is only matter. Thats why i posted all those in details, so others can check and maybe gain same results as mine or even better. Further others can notice some mistakes and let me know. Mutual benefits. Common experience is much better than single one. If i was smartest man here i would never come and ask for second opinion...
Geo just try it and see. If no benefit, at least you will know for sure.
Best regards!

[Qiaozhi]

Wise and funny guys here!?
Quiaozhi i respected you so far. Right now i am reconsidering that.
So many suggestions and tips from you but so less benefits from those.
It is easy to stand aside, ocassionally "drop" some "wide" suggestion and tip...When things oposite your attitude than you showing some pictures and simillar... I understood this place as place when i can talk seriously with people with which i have common interest.If sometimes we dont agree, than i expect to explore problem in details and find spots of disagreement...
If you are tired of taking seriouslu part in here, or dont want to waste your precious time with us here, fine. But please dont act like a wise guy.Sooner or later you'll make mistake...
PorkLuvr's remark about "horse..." wasnt offended me at all. I understood it as a joke. Your post is offending me and i can not take it as a joke.
Anyway like i said, so less benefits from your posts here.Plain academic rethoric. Any "greenhorn" can google arround the .net and find "deep" scientific explanations...blah..blah...and simillar.
But i still havent saw any of your handmades (this doesnt mean that i want to see those here)...
Except few rare members here i can only take seriously Max,Geo and my Dutch friends cose i saw their work in practice,efforts,problematics...
That is what i do respect for real. Plain academic rethorics not!
Further i can take jokes and critics only from them, but not from person with which i do not correlate at all....
Pleas stay away of peaking me further.
Regards!

Ivconic - you have totally misunderstood my "joke", and the previous one by Porkluvr. "You can lead a horse to water, but cannot make it drink" is a common reference that is used when you are trying to help someone, but they are not listening. Porkluvr and I are using simulation (and also Max) to assist you with this problem. However, you do not seem to believe the simulation results. That's all it means. There is no disrespect meant by anyone here.

Yes - it is true - I do not intend to build the TGSL, but I fully understand how it works. It is a classic double-differentiating design. There's no mystery here.

I am very busy at the moment with some other projects - not known about here - and can only pop in from time to time.

[ivconic]

"...when you are trying to help someone, but they are not listening. Porkluvr and I are using simulation (and also Max) to assist you with this problem. However, you do not seem to believe the simulation results. That's all it means. There is no disrespect meant by anyone here.
Yes - it is true - I do not intend to build the TGSL, but I fully understand how it works. It is a classic double-differentiating design. There's no mystery here.
I am very busy at the moment with some other projects - not known about here - and can only pop in from time to time...."

No, i understood it very well. PorkLuvr suggested simulator and i accepted. I am still using it. I do not trust it - yes, it is true. Why? Cose it showed one result and practicing primer showed another....many times, not only once.
Disrespect.....or respect....really doesnt matter, but showing it in public it is matter much!
You fully understand how it works....i belevie yes! On principle bases yes! In details....i dont think so! There is no mistery here....yes i agree - no mistery...but details,details,details...you are not awared of every detail here....neither than me, to tell you the truth. But you are relying your attitude on principles you are knowing (it seems) very well, and further you are risking to adopt prejudices, generally speaking.
Each of Tesoro designs is story of its own, no matter if those are pretty simillar....If you dont trust this, than you are not informed well. Until try and build it yourself....i really dont know how to close this up, more to you. Never mind. I have my reasons not to relly on simulator here. And my attitude on this should not be subject to joke about..
PorkLuvr has right to compare me to a horse from that story, you dont!
Anyway...it is stupid to continue with this any more....I'll stop. What has been posted here .....is posted...no more from me....I'll stick strictly to subject here from now on. Subject is TGS...

[Geo]

If this does matter than i really dont know!? But i straighten up previous signal with 220-330pF and gained clear square. Is there any benefit from that, again i dont know. I do know my TGSL works like a hell, and that is only matter. Thats why i posted all those in details, so others can check and maybe gain same results as mine or even better. Further others can notice some mistakes and let me know. Mutual benefits. Common experience is much better than single one. If i was smartest man here i would never come and ask for second opinion...
Geo just try it and see. If no benefit, at least you will know for sure.
Best regards!

Hi Ivica.
Most basic for me is to understand how and why it work. I want to trace the signal and to see if it is Ok or not. If it is wrong i am looking to solve the problem. But here we are 4....5 persons with TGS where all detectors works but with different signal. What to see???? Is the sinus right, or the square??. For me this is the worst. I don't like a detector that work very good.... perfect but "from mistake". Today when i will finish my work i will give it a try again. Who knows......... Maybe Max find the right signal.... sinus or square
My regards

[Geo]

I atach again the form of signal that yesterday i took from TGS. The upper signal is from pin1 of LF353 (8V p-p) and the other at the out of RX Ampl (LF353 pin7????? i dont remember, 150mv p-p). Scope was synchronised with channel2. I attach one file more with the coins that always i use for tests

[Qiaozhi]

Hi Ivica.
Most basic for me is to understand how and why it work. I want to trace the signal and to see if it is Ok or not. If it is wrong i am looking to solve the problem. But here we are 4....5 persons with TGS where all detectors works but with different signal. What to see???? Is the sinus right, or the square??. For me this is the worst. I don't like a detector that work very good.... perfect but "from mistake". Today when i will finish my work i will give it a try again. Who knows......... Maybe Max find the right signal.... sinus or square
My regards

Thanks Geo. This is exactly my point. There is a deliberately "stubborn" attitude here in trying to really understand the problem. Yes, it does appear to be working "from mistake" (as you say) but the worrying thing is the inconsistency.
Good luck, and I hope you solve the mystery soon.

[Max]

Hi,
c'mon guys... be quiet...

I think that we have to avoid jokes for now and focus to the problem only... and the problem is:

is the signal at pin1 of 353 required to be sinus shaped ?

I think so... but that's my personal opinion... from my understanding of the disc syncro system of TGS (like other detectors too by Tesoro expecially BandidoII) it's required having an increasing signal at that point cause that way you can move further or backward the disc sample pulse.

That's what I get in BandidoII for real, measuring with scope I mean.

The simulator can solve all our problems with TGS !? Of course, NOT.

It's impossible simulate all conditions that could happen in the "real" circuit on PCB... sockets and all the number of things that have to do with real assembly of board is not just like using the plain schematic.

I've just made some simulations to show why the LF353 goes into saturation so easy with higher cap value: reactance

But there are more things... for example yesterday I've simulated the 50Kohm influence as feedback resistor... and simulator showed a good shaped near-to-sinus wave with 100pF... but early in this morning I've made the real test and yes... there is a similar to sinus wave... but also some small ringing on one part of wave that there isn't in simulation. That explain everything... no simulation is perfect, no simulation parameter list is "complete" -> there's always a gap between simulated things and real signals from pcb.

About the 220pF (or 330pf) it works about sens like Ivconic stated... I've not tested disc effects using that mod on the real circuit... so I cannot say if it still works on the PCB... I've made that simulation that say the disc sample will happen always at same time (phase shift) even moving the pot: on this I think simulation is right... cause I was thinking the same before made that on LTspice... just using my understanding of circuit.

I'll check this too on real board to say if it still works... and if so to understand why: we have also consider that a comparator needs few uV differences at inputs to work... so even a few angles edge of "square" wave could be enough to move forward of few degrees... so acting still as disc.

Infact... if you look at simulation you see vertical edges (without zoom )... and all we know here that's impossible having that on "real circuits"...so all depends on how much is that inclination of the edge.

We have just to test and see on PCB... if data from simulation match or not our measures.

Best regards,
Max