Start TGSL built

[ripsdevala]

This is much better.
Now you can check the frequency, when you put the RX coil in TX cirquit. In your case, you should have approximately 14,7 kHz.
approximately

That test is do with Rx and Tx connected,
Let me try without Rx

[ripsdevala]

That test is do with Rx and Tx connected,
Let me try without Rx

Sorry miss reading, let me put Rx to Tx

[ripsdevala]

This is much better.
Now you can check the frequency, when you put the RX coil in TX cirquit. In your case, you should have approximately 14,7 kHz.
approximately

Tx 14khz 10us 7.12div
Put Rx to Tx
Rx 13.4khz 10us 7.42div

[blobber]

Yes you are right, I was wrong...sorry. That's correct what you have now.
Well, now you could connect the coil in normal way, and adapt the parallel capacitor C6 in RX tank , to see what's happend, when you change the value in steps of 1 or 2 nf, while watching the RX output. Around 15 nf, you will have probably the highest level of P-P in RX output, later you can do fine tuning here, with iron washer or coin, to get the minimum again.
Also you will see now, the proper relationship in TX and RX. But do it away of any metall. When you has chosen your value for C6, than you should follow the procedure in your pdf file, while checking all measurement points.
Your coil is already fixed with epoxy?

[ripsdevala]

adapt the parallel capacitor C6 in RX tank , to see what's happend, when you change the value in steps of 1 or 2 nf, while watching the RX output.

What is the best output should i get when i change in steps of 1 or 2nf?
I already put epoxy on it, i have non epoxy coil to, should i change it?

[ripsdevala]

I get this on step 4 dons pdf
J1-1 Tx (top) 20us 5v/div
Pin 7 LF353 (bottom) 20us 5v/div if i go bellow 0.2mv the signal is expand and gone.
Is this normal

[blobber]

I mean, when you adapt the RX capacitor in small steps in sum of 10-20 nF, you will get somewhere a maximum in RX output. The value depends of your nulled coil, I do not remember which I had there. I was only looking for the max. amplitude.
Use your fixed coil for this step, you make later fine tunning and watch always TX and RX at the same time.

[blobber]

I get this on step 4 dons pdf
J1-1 Tx (top) 20us 5v/div
Pin 7 LF353 (bottom) 20us 5v/div if i go bellow 0.2mv the signal is expand and gone.
Is this normal
[ATTACH]37053[/ATTACH]

What you have for RX output in mV now?
Sorry I write on my mobile phone, so I could not see your last post.

[ripsdevala]

Forget my last post, im put wrong cable.

[blobber]

Okay.

When you also change two resistors in TX circuit (yellow marked), you will also have 20 V p-p.

[ripsdevala]

I got only 13.3 khz for Tx, using original thread v.3 coil
How to increase it?
With smaller diameter i have 14khz.
And still make double beep from coin surface, not from thin side. Already try to swap Rx cable.

[ripsdevala]

J1-1 Tx (5v) vs LF353 pin 7 (50mv) 20us

[ripsdevala]

What output voltage you get from Tx and Rx or its vary on the coil? Le me take a bath first....

[ripsdevala]

This is my setup
Coil

Board

Tx vs Rx at 5v 20us 10nf Rx


Full video
https://youtu.be/CHnUz5yHpyg

[ripsdevala]

Okay im done, the best is 30cm with pft...pft sound
Btw uaing NE5532 get better result on some trasy coin detecting.
Change Tx caps to get 14.5khz, before i just gwt 13.3khz
It cant be nulled to 4mv the best is 17-30mv, the pin 7 u101 have sinewave, so it canot be zeroed, maybe i dont know how.
Waiting LM8833 as blobber sugested, for now lets use the what i get.
Poor me.... Good day all

Rips