IGSL

[ivconic]

Dfbowers, i noticed some benefit from it.
At very first setup from the first page of this topic; i had TX amplitude only 9vpp!? Maybe it is not proper reading because my oscilloscope is very old and "noisy" (Telequipment D54...almost older than me!)
So i tried to rise up amplitude by changing R1. I lowered it's value in few steps and got higher and higher amplitude.
Now R1 is 560 ohms and amplitude is 13vpp - taking that my D54 is accurate (which i seriously doubt now).
But TX sinus was a bit distorted with noticeable "notch" on the top. Also i couldn't get more significant air depths with such risen amplitude!? So i decided to remove FET parts (again) from the pcb and experimented with resistances there. Initially 47k was there; so i used 100k trimer and adjusted it while observing scope behavior. At some point "notch" disappeared and pretty clean sinus appeared on the scope. Depths improved and overall behavior looks kind a better then before. But now frequency is not 14kHz as it was - now is 14.6kHz.
Now this reminds me to say again that R1 is not 2k2 anymore - now is 560ohms.

[satdaveuk]

Please correct me if I'm wrong, but I thought you were building the original TGSL (Tesoro Golden Sabre Light) and not the IGSL (Ivconic Golden Sabre Light). If so, you are posting in the wrong thread.

Yes your right im loosing it i think lol

[dfbowers]

Selim you don't need another pcb, that one is just fine. Just omit fet part from TX stage and somehow include that trimmer. It improves overall performances - now with that trimmer you can adjust perfectly nice sinus at TX output. I also added 2 capacitors at RX input, because my RX coil is exactly 6.5mH and i found out that 14.7nF (10nF+4.7nF in parallel) gives me PERFECT resonance relation, which resulted with 2cm gain at coin in air depths.

Also i rise up gain at first opamps in channels (1M5 instead 470K). No harm (no false signals and no instabilities later) but also another improvement in sensitivity. And at the end i added treshold control, because now with those trimmer you can shape up a bit more audio to get nice and very pleasant output.
And also, finally i choose different 4024 outputs and finally that is it! Best possible audio combinations.
I can not explain correctly, but i noticed that some frequencies from 4024 are not most suitable to be used for audio stage. With this, latest, updates at 4024, i have feeling that everything goes on it's place, audio now is acting pretty smooth, much better than before.
Updates gave me better results now; same coin now at 28cm in air, Cu plate 5x5cm at 60cm and more. Better GEB and Disc behavior and stability is just PERFECT.
So...
I will rearrange pcb now...

Ivconic,

Can you elaborate on the advantages of adding a trimmer to the TX oscillator and adjusting the shape of the sine wave? (I have to try it.. I would like to see if my results are the same).

Also, I have always been a fan of a detector with a threshold. Unfortunately, I have not built the IGSL yet and the TGSL does not have regulated power source for the LM358 (U107) like the IGSL does. I suppose I could cut the trace and jumper it to the regulated +8v source.

While experimenting, I can improve the audio response of the TGSL by decreasing R44 (2k2) but I am unable to actually find a threashold. Maybe this is because the power sources are unequal e.g. -5 and +12v?

Don

[Jerry]

Very Nice Looking Board Selim.

[pigeon]

hi Ivonic and Selim

thank you very much

[selim]

[ivconic]

Тhanks PaullyG, i will try it!

[PaullyG]

I had to compress .avi file because it was over 150Mb!! Seems Dr.DivX degraded audio much and added those "harmonic" at record! I adjusted Dr.DivX to compress in high resolution and with 128kbs for audio... yet it distorted audio much!

You'll likely have better luck with Handbrake for transcoding your videos. Plenty of documentation on the site if you get stuck but it's a pretty straight forward app once you know your way round.

[Qiaozhi]

Hi
Quick update on my faulty IGSL ...

Please correct me if I'm wrong, but I thought you were building the original TGSL (Tesoro Golden Sabre Light) and not the IGSL (Ivconic Golden Sabre Light). If so, you are posting in the wrong thread.

[ivconic]

"...but i checked supplies again the -5V varys between -3/-8v, is this normal?.."

No it is not. It should stay -6v all the time. Looks like you have something wrong or faulty put on your pcb? Say... have you reversed D3?

[satdaveuk]

I want to get sorted soon because i have a dead line for the 6th august to give it a pro field test along with other machines its beach, pasture, plough all here in England so the it really will show what this kit is made of , could go either way but im thinking positive but its paramount i geta few days out in the fields with it before hand.

Warm regards
Dave

[satdaveuk]

Hi
Quick update on my faulty IGSL, only had a hour on it last night and now i need work, but i checked supplies again the -5V varys between -3/-8v, is this normal? double checked circuit to component placments, all seem correct.
Strange fault but ill nail it, nice tone comes up on switch on but stays there, i can stop it by nulling which again seems ok, but it wont detect anything , and i mean nothing at all, none of the controls do anything and again i mean nothing so when i get time i will scope the RX amlifier stages and go from there.
As i said its a strange fault because when switching on you think its going to work nice sound know distortion, RX/TX stages far as frequencys seem to be to spec.
All i need is 2-3 hours in the workshop with those handy test points thats been kindly donated im sure i will crack the problem.
But in the meantime if someone here has had this problem and solved it please let me know, i would be so greatful.
O by the way while i remember aonics you did a mod on this project to bump the gain up and help match the inputs to the LM08s, can you please put it on here for me so when its up and running i can do the mod.
Many thanks in advance
Dave

[ivconic]

Aha, one more thing! To void confusion; my present coil is not 28cm like it was before - it is 24.5cm now. I used scraped Minelab TS1000 coil enclosure and made suitable coil for IGSL, with: 6mH for TX and 6.5mH for RX. So 28cm for same coin in air tests is not such bad result after all. Todays results are more that satisfactory: no masking at all (actually, masking is not possible with such design, that's why i make it!), no false signals at all, GEB is PERFECT, response even on smallest metal items is momentarily - no delays at all! Various adjusting combinations of those 2 "Disc" potentiometers gives me variety of mixing between two "ranges" (wanted and unwanted targets-alloys)! So... i think "this would be beginning of beautiful friendship"!

[ivconic]

Selim you don't need another pcb, that one is just fine. Just omit fet part from TX stage and somehow include that trimmer. It improves overall performances - now with that trimmer you can adjust perfectly nice sinus at TX output. I also added 2 capacitors at RX input, because my RX coil is exactly 6.5mH and i found out that 14.7nF (10nF+4.7nF in parallel) gives me PERFECT resonance relation, which resulted with 2cm gain at coin in air depths.

Also i rise up gain at first opamps in channels (1M5 instead 470K). No harm (no false signals and no instabilities later) but also another improvement in sensitivity. And at the end i added treshold control, because now with those trimmer you can shape up a bit more audio to get nice and very pleasant output.
And also, finally i choose different 4024 outputs and finally that is it! Best possible audio combinations.
I can not explain correctly, but i noticed that some frequencies from 4024 are not most suitable to be used for audio stage. With this, latest, updates at 4024, i have feeling that everything goes on it's place, audio now is acting pretty smooth, much better than before.
Updates gave me better results now; same coin now at 28cm in air, Cu plate 5x5cm at 60cm and more. Better GEB and Disc behavior and stability is just PERFECT.
So...
I will rearrange pcb now...

[ivconic]

I must confess, now Novak is superior, has shown several times.
but I am Spanish and there is still hope.
next year, will be interesting.
IGSL'm sure not repent, all your projects are winners.

Against everybody else (except against Novak) i do take Rafa as "my side" and my favorite No.1. Rafa is most likable and favorable foreign tennis player here in Serbia. Only in situations when he playing against Novak - he is not our favorite here. So.. that's life and that's sport. God bless both; Novak and Rafa!

Selim that's very NICE WORK! Before you continue - take a look on my latest updates here: