TESORO GOLDEN SABRE

[ivconic]

OK - the top two traces are the inputs to the synchronous demodulators. These look ok to me. In trace one you can see that GEB is sampling at the positive-going zero-crossing point. In trace two you can see the DISC sampling should be at the peak of the waveform for ferrous discrimination, so I guess the DISC pot is turned fully anti-clockwise here.

The waveform at the LF353 pin1 looks wrong. It's being driven into saturation and there's some instability there. I've used this configuration in the past, and it's clearly not right. Have you looked at what happens to the waveform when you turn the DISC pot? There's definitely a problem here. Are you sure you measured the correct point in the circuit? I have to ask ...
Receive and transmit look good.

Can you also probe the outputs of U106A and U106B? In particular, look at the waveform when you wave a coin at some distance from the coil so that the audio signal is weak.

Actually it is not fully anti-clcokwise...Damn! It is a bit over half in clockwise direstion!???
Yes i suspected signal from pin 1. of LF 535 at once...!I?
I'll scope outputs of U106A and -II- b and see what happens...

I was absent a while.... Now have to go again. Be back soon...

[ApBerg]

LF353-1

Hello Frends.

Qiaozhi, in the past I had some problems with wire wound pots, when replaced by a 'normal' pot the problems were gone, can it be that there is an L function ?

Well made some screenshots, transmit sinus is 2 v p/p also the 353-1 is 2 v p/p for the r25 and r26 signals it is 0.2 v p/p ( I hope..... can be wrong )

First is LF353-1 then two from r25-q7 then two r26 q6

Ap

[Qiaozhi]

Hi,
yes his lF353 goes into saturation at top of curve... and that's no good... but I think there is a problem on the sampling at DISC (fet #2).

Seems a double pulse of sampling.

Kind regards,
Max

Yes - there is a problem with the sampling in the DISC channel (fet #2), but at least it's sampling in the correct place. I think the double pulse is happening because the sample pulse has that strange instability.

The signal at 353-1 is wrong......!?, think you both use wirewound disc pot?
Think it must be a nice sinus !
Wil make some pictures, mail them.

Why do you think a wirewound DISC pot would cause any problems?

[ApBerg]

Lf353-1

The signal at 353-1 is wrong......!?, think you both use wirewound disc pot?
Think it must be a nice sinus !
Wil make some pictures, mail them.

Ap

[Max]

OK - the top two traces are the inputs to the synchronous demodulators. These look ok to me. In trace one you can see that GEB is sampling at the positive-going zero-crossing point. In trace two you can see the DISC sampling should be at the peak of the waveform for ferrous discrimination, so I guess the DISC pot is turned fully anti-clockwise here.
The waveform at the LF353 pin1 looks wrong. It's being driven into saturation and there's some instability there. I've used this configuration in the past, and it's clearly not right. Have you looked at what happens to the waveform when you turn the DISC pot? There's definitely a problem here. Are you sure you measured the correct point in the circuit? I have to ask ...
Receive and transmit look good.

Can you also probe the outputs of U106A and U106B? In particular, look at the waveform when you wave a coin at some distance from the coil so that the audio signal is weak.

Hi,
yes his lF353 goes into saturation at top of curve... and that's no good... but I think there is a problem on the sampling at DISC (fet #2).

Seems a double pulse of sampling.

Kind regards,
Max

[Qiaozhi]

So i listened Quiaozhi's suggestions...i played arround KOP's hysterezis....not even close! Same behavior...!

I decided to take shots from some oscilograms....Yes i know; my osci. is obsolete and funny...yet here are some shots...
Only thing is not clear to me is osci at 1.pin of LF353?????

OK - the top two traces are the inputs to the synchronous demodulators. These look ok to me. In trace one you can see that GEB is sampling at the positive-going zero-crossing point. In trace two you can see the DISC sampling should be at the peak of the waveform for ferrous discrimination, so I guess the DISC pot is turned fully anti-clockwise here.
The waveform at the LF353 pin1 looks wrong. It's being driven into saturation and there's some instability there. I've used this configuration in the past, and it's clearly not right. Have you looked at what happens to the waveform when you turn the DISC pot? There's definitely a problem here. Are you sure you measured the correct point in the circuit? I have to ask ...
Receive and transmit look good.

Can you also probe the outputs of U106A and U106B? In particular, look at the waveform when you wave a coin at some distance from the coil so that the audio signal is weak.

[Max]

No problem of course!
I'll be awake until 4 o'clock this evening (morning)....sa any other night...
If you achive to do that today, fine. If not, than tomorrow is just fine also..
Thanks in advance!
Regards!

P.S.
Now you have rough picture of my oscillogramms....You can do some rough comparsions, also, with results you gain measuring your device...If you notice major differences, let me know..
Also you can suggest me what other spots i can measure and get oscillogramms for further comparsions....Actually you can suggest me now, so i'll prepare those for tonight..

Hi,
sorry for bad quality ... I need a tripod or something to do better cause of latency required inside by camera to shoot pictures.

Actually I haven't around so used hands... and pictures are about "moved"...anyway you could see my signal is different:

-on top you see the signal at osc, collector of 2n2907
-under is the pin1 of lf353 and it's parabolic like... with some spurious sinusoidal noise

Channels amplitude is 5V/square (but can you see squares ?)

This time I can't do better...

Hope you see the difference!

Kind regards,
Max

[ivconic]

No problem of course!
I'll be awake until 4 o'clock this evening (morning)....sa any other night...
If you achive to do that today, fine. If not, than tomorrow is just fine also..
Thanks in advance!
Regards!

P.S.
Now you have rough picture of my oscillogramms....You can do some rough comparsions, also, with results you gain measuring your device...If you notice major differences, let me know..
Also you can suggest me what other spots i can measure and get oscillogramms for further comparsions....Actually you can suggest me now, so i'll prepare those for tonight..

[Max]

Max can you scope your LF353 pin 1. and post it here?

Something is "misty" here???

Hi,
yes, of course, but I need a few time (maybe I can for this evening or tomorrow in worse case).

Best regards,
Max

[ivconic]

Max can you scope your LF353 pin 1. and post it here?

Something is "misty" here???

[ivconic]

So i listened Quiaozhi's suggestions...i played arround KOP's hysterezis....not even close! Same behavior...!

I decided to take shots from some oscilograms....Yes i know; my osci. is obsolete and funny...yet here are some shots...
Only thing is not clear to me is osci at 1.pin of LF353?????

[ivconic]

TikTak i dont need notch, that's why i omited it...
Why the hell nobody reads all the posts from this sad forum?????
How many times simillar questions...???

[ivconic]

Quiaozhi while mentioned Monte Carlo analysis...? Its better to use Daytona analysis instead...!!! Shheeeeshhh!!! Or Le Mans analysis even better...!?

BS

[Max]

I have made the first PCB with NOTCH.
Why you remoove NOTCH section Ivconic?

Hi,
can I answer ?

Cause he don't need notch, cause notch section waste 40% of energy if you don't need it, cause you have to buy and mount components and make larger board, you need a larger case, you carry more weight, you need another pot and 2 switches more...and much of luck with comparators... and if you don't need why complicate life ?

Another issue is that notch could also introduce more noise there YES!

I've the original board with it... and I'm start thinking that maybe I need build goldy or the Vladimir's one cause of the reasons of above... but I'm happy with original board... cause I've found some workarounds like the TLC2262 to solve some big problems... and occasionally I've used notch to cancel foil in one infested site...and works cool for this...well you will miss also some gold... but who cares of gold ?

Best regards,
Max

[Max]

Hi Max,
I am using DT9205A multimeter, it have 200 mV range in AC.And like you say 1M resistor and 15N capacitator paralel and conected to RX.And look for .000!
So If my problem is nulling then............

I have a few more questions for You and Ivconic:

1.Have you reach 35 cm for 1 denar in air with 1M modification of not?

2.When you wind coils you start winding from bottom and you moove up without turning back or you make few layers?

3.I can find KA and TEA 2262 can I use this for TLC2262 or they are different things?

Thanks

Hi tiktak,
you have to use 1K resistor not 1M... and of course the 15nF cap.

You can null using multimeter (I can too, I've tested and works cool) but be sure you gain exactly 0.0 mV not 0.1mV or something more or e.g. -0.1 ...cause otherwise you have maybe 20mVpp or more on coil and that's not so good.

1. without 1M mod for audio I get signal too but sound is weaker than with it... so I get e.g. 1eur coin at 34cm about loud without 1M resistor, with it I get with loud sound from 35-36cm too, that's about top of the range for it. That's more important with smaller stuff like small 1eur-cent coins , with 1M I get loud sound where I just cannot hear sound on speaker without cause is very weak. VERY WEAK BUT THERE IS ALWAYS... I mean if I use headphones I hear easy all small sounds I have without the 1M resistor.

2. I wound totally coil from start to finish from bottom (wood plane), and don't use separate layers... if you watch at my posted picture you will see that thing.

3. NO. KA and TEA2262 are ic for SMPS used in TVs and the like... they aren't op. amps. you have to find TLC2262 or you can try with TS27M2 for instance.

Best regards,
Max