TESORO GOLDEN SABRE

[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!

[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!

[Qiaozhi]

Hi Porkluvr,

I'm afraid you may be correct.

[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

[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.

[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]

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!

[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

[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,
no need to use scope...

Look:

1st picture is simulation with disc pot wiper=0.5 , up signal is out of comparator and down in green is the pin1 of 353

2nd picture is same stuff with wiper=1 (100%)

All the same... you turn pot and nothing will happen... disc is always at min.

Check yourself.

Kind regards,
Max

[Max]

No Max, i dont think it is mistake. Yes i think there should be 100pF, not 220-330pF. I only suggested it due experimental purposes. Adding it an scoping again you will see quite new situation related to pin 1. of LF353, also right transition in Disc range.

Only God knows what are really differences between our handmades and original TGS?? If we talk about manufacturing quality, components used etc.
About rings....I dont think these are problems. It is easy to isolate inputs for testing. I did that - no changes...
You need rings only at ultra high impendanced inputs....here is not that situation...
On your scope i can see simillar saturation at LF353 as was in mine. Thats why i suggested to put 330pf and see; saturation disapeared...
OK. I might be wrong in may things here....but fact is that my TGSL works absolute correct in all modes at all presets...? Also depth is great...
I finished this thing....no matter some simulator results and oscillogramms doesnt suits to "some" theories here.

PorkLuvr compared me to a horse! OK...but i still refuse to take this simulator 100% accurate. Practice proved oposite...Not only mine practice...


Quiaozhi it is not big deal at all to learn to use some software. I being practicing simillar from 1982. (when where you born?)
Question is are these softwarez really accurate and applicable in all situations to all cases? I dont think so....especially if those are freeware...

If i were you, i would better learn to use Mathlab.
Regards!

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

[Max]

No Max, i dont think it is mistake. Yes i think there should be 100pF, not 220-330pF. I only suggested it due experimental purposes. Adding it an scoping again you will see quite new situation related to pin 1. of LF353, also right transition in Disc range.

Only God knows what are really differences between our handmades and original TGS?? If we talk about manufacturing quality, components used etc.
About rings....I dont think these are problems. It is easy to isolate inputs for testing. I did that - no changes...
You need rings only at ultra high impendanced inputs....here is not that situation...
On your scope i can see simillar saturation at LF353 as was in mine. Thats why i suggested to put 330pf and see; saturation disapeared...
OK. I might be wrong in may things here....but fact is that my TGSL works absolute correct in all modes at all presets...? Also depth is great...
I finished this thing....no matter some simulator results and oscillogramms doesnt suits to "some" theories here.

PorkLuvr compared me to a horse! OK...but i still refuse to take this simulator 100% accurate. Practice proved oposite...Not only mine practice...


Quiaozhi it is not big deal at all to learn to use some software. I being practicing simillar from 1982. (when where you born?)
Question is are these softwarez really accurate and applicable in all situations to all cases? I dont think so....especially if those are freeware...

If i were you, i would better learn to use Mathlab.
Regards!

Hi Ivconic,
so you say that the 220-330pf alternative make things really good on TGS. Nice , I will try that too.

I suggest also Geo try this too... seems to me that Ap wrote about the fact he tested already and results are like yours.

I just don't understand they at Tesoro then... maybe was their mistake putting a 100pF on input of 353 ?

What make me crazy is that sometimes the wave is distorted and other times is clean sinusoidal...

BTW I think that simulator is ok ...but in simulations something were wrong I mean we have to simulate also intercapacitance due to socket etc... for having a more realistic simulation of problem at pin1...otherwise is like simulating the aerodynamic of a car in vacuum ... have not much meaning.

Anyway, I'll test with values from 220 to 330pF there to see the effect in next days... then I'll report here.

Best regards,
Max

PS: I've played too with computers from childhood ... but that was in the 80's... at that time used first stuff with something 32Kbytes RAM (made in england product by Grundy B. Systems) all in basic CP/M.

[ivconic]

Hi Ivconic,
why do you think that 220-330pF is the right value ?

In schematic it's 100pF. Of course... you will say that it works better with 220-330pF, and that you have square signal now... but then schematic has a mistake there ?

Do you think it's a mistake on schematic or that 220-330pF is a good workaround!?

Kind regards,
Max

No Max, i dont think it is mistake. Yes i think there should be 100pF, not 220-330pF. I only suggested it due experimental purposes. Adding it an scoping again you will see quite new situation related to pin 1. of LF353, also right transition in Disc range.

Only God knows what are really differences between our handmades and original TGS?? If we talk about manufacturing quality, components used etc.
About rings....I dont think these are problems. It is easy to isolate inputs for testing. I did that - no changes...
You need rings only at ultra high impendanced inputs....here is not that situation...
On your scope i can see simillar saturation at LF353 as was in mine. Thats why i suggested to put 330pf and see; saturation disapeared...
OK. I might be wrong in may things here....but fact is that my TGSL works absolute correct in all modes at all presets...? Also depth is great...
I finished this thing....no matter some simulator results and oscillogramms doesnt suits to "some" theories here.

PorkLuvr compared me to a horse! OK...but i still refuse to take this simulator 100% accurate. Practice proved oposite...Not only mine practice...


Quiaozhi it is not big deal at all to learn to use some software. I being practicing simillar from 1982. (when where you born?)
Question is are these softwarez really accurate and applicable in all situations to all cases? I dont think so....especially if those are freeware...

If i were you, i would better learn to use Mathlab.
Regards!

[Max]

Hi all,
I got another bright idea

Isn't LF353 a jfet input op amp ?

Where are guard rings ???

I mean we have input pins 2 and 3 with socket... and then no guard rings near them ! Could be a self oscillation due to capacitive coupling at differential inputs !?

We need to sing a mantra now... WE NEED GUARD RINGS ! WE NEED GUARD RINGS ! (maybe works)

about zener ... here is the pearl:

.model MAX3v9 D(Is=1.5n Rs=.5 Cjo=185p nbv=3 bv=3.9 Ibv=1m Vpk=3.9 mfg=MAX type=zener)

Best regards,
Max

[Max]

That's why I think 100pF is right value on TGS there...

look at Toltec100 part (schematic by Merc revision #3 of few days ago)

It's 100pF with LF353 too... cannot be a case ...also other disc stuff is similar.

What do you think ?

Best regards,
Max