TESORO GOLDEN SABRE

[ApBerg]

LF353

Hello Frends.

Made some test, chanced the Send TR 2N2907 and the stab. zenerdiode 4.3V. Replacment TRs were 2N3905 Bc557 zeners from 3.9 - 5V1.
The erretic noise had to do with this al.... !
Look at the results on LF353-1 !? ( Geo save some wisky ....hik ).

So care is needed in the transmitter part ?
I do not have the answers for this, maby Porklver can make simulation ?

[Darko]

re:


Actually, from my TGS couple days earlier come out a magic smoke and I know ,when this magic smoke come out from TGS he had tendency to don’t work anymore. This is really strange thing for me but this is what happens when someone is very impatient, like me. Now I waiting for new IC’s from local suplier.

Anyway, i am glad to see that you finally made coil with detection over 30cm...Bravo! Good job!

[ApBerg]

LF353-1

The Send TR was not 2N2905 but 2N2906 !

See post 1426

[Qiaozhi]

Very good work Max!

Having studied the results of your analysis, I would conclude that the detector is working correctly, as designed. However, with the TGS Lite version, it would probably work better with the GEB and DISC sample circuitry from the Bandido II. I expect this would get rid of the spurious oscillations at pin1.
The main problem I can see is the oscillations at testpoint 12. These are the oscillations I've referred to many times, but everyone has denied this is happening! BUT - it's obviously there after all! This occurs for the simple reason that inputs to these comparators are hovering around the threshold crossing point, and random noise is causing the comparator to switch from one state to another. I would suggest that this is an area in need of improvement. The slight fluctuations at pin 1 are not actually causing any problems in the synchronous demodulators (as confirmed in practice by Ivconic) so IMHO I would ignore this at the moment.

[Max]

Hello Frends.

Made some test, chanced the Send TR 2N2907 and the stab. zenerdiode 4.3V. Replacment TRs were 2N3905 Bc557 zeners from 3.9 - 5V1.
The erretic noise had to do with this al.... !
Look at the results on LF353-1 !? ( Geo save some wisky ....hik ).

So care is needed in the transmitter part ?
I do not have the answers for this, maby Porklver can make simulation ?

Hi,
this is really interesting... so maybe is just overload signal from TX that make LF353 crazy ?

I have to try simulation with 3.9V or 5.1 but I can't find them on LTspice ???

I need some more whisky ! (Actually is "Baileys" not just whisky... and lot of smoke too...real fog now...)

Let me find some zener and I'll post a new simulations in matter of minutes...

Kind regards,
Max

[Max]

Very good work Max!

Having studied the results of your analysis, I would conclude that the detector is working correctly, as designed. However, with the TGS Lite version, it would probably work better with the GEB and DISC sample circuitry from the Bandido II. I expect this would get rid of the spurious oscillations at pin1.
The main problem I can see is the oscillations at testpoint 12. These are the oscillations I've referred to many times, but everyone has denied this is happening! BUT - it's obviously there after all! This occurs for the simple reason that inputs to these comparators are hovering around the threshold crossing point, and random noise is causing the comparator to switch from one state to another. I would suggest that this is an area in need of improvement. The slight fluctuations at pin 1 are not actually causing any problems in the synchronous demodulators (as confirmed in practice by Ivconic) so IMHO I would ignore this at the moment.

Hi,
yes I confirm too that it works perfect even with the strange pin1 ringing... but it's interesting understand why sometimes happens and some other times not... even with same brand LF353N.

Yes at comparators there are fluctuations that are then showed as noise on speaker. On strong bursts (e.g. what I get with fakes 308s) they are so often present that one could see really easy on screen and hear from audio...

So you are 100% right on that thing... it happens cause of chain noise amplification... so would be better using some less noise affected amplifier in the middle to avoid much problems like that.

Best regards,
Max

[ivconic]

Darko and TikTak regards to you both! You asked simillar questions, reported simillar problems...logically i assumed there is one - same person. I still have doubts on that... Never mind! Regards to "both" !
Smoke you said!? There is no smoke without a fire , i said!

Back on subject;

Who pronounced idea that on pin 1. must be sinus??? Who was the first actually to said that?
I am sure there must be "clean" square, as i posted. If you want to be sure that everything is right there; replace 100pF with 220-330pF and after than scope it! Later we can talk...

Take another look on my video and you will see full transition from sinus to square when Disc. pot is turned full scale. If some jitters on the video bug's you, i must explain those are due old and "rusty" oscilloscpoe - it's inner hums... Generally video is good enough to see full transition in full range - covering whole amplitude...
You can test your device by scoping pin 2. of LM393...

[Max]

Hi all,
the simulator just don't care of zener voltage !

I cannot find the model for 3.9V so I've made my own 3.9V zener... "MAX" brand... (but it works!).

Effects of the whisky... don't care... but look at picture!

Kind regards,
Max

[Max]

Darko and TikTak regards to you both! You asked simillar questions, reported simillar problems...logically i assumed there is one - same person. I still have doubts on that... Never mind! Regards to "both" !
Smoke you said!? There is no smoke without a fire , i said!

Back on subject;

Who pronounced idea that on pin 1. must be sinus??? Who was the first actually to said that?
I am sure there must be "clean" square, as i posted. If you want to be sure that everything is right there; replace 100pF with 220-330pF and after than scope it! Later we can talk...

Take another look on my video and you will see full transition from sinus to square when Disc. pot is turned full scale. If some jitters on the video bug's you, i must explain those are due old and "rusty" oscilloscpoe - it's inner hums... Generally video is good enough to see full transition in full range - covering whole amplitude...
You can test your device by scoping pin 2. of LM393...

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

[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

[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

[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]

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.

[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]

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