Another version of TGSL

[ZdenekHQ]

No, I have pre-amp in distance about 40cm from coil, because I had troubles with cable. Cable between coil and pre-amp is hard fixed and dont make false signal. If you have electronic fixed to coil holder, it is not needed, but i am testing my detectors with electronic in separated case, moving of cable make troubless.

[ivconic]

Interesting!
I have few observations/questions;

- C36 is noted as 1000uF? Is it 1000uF or 100uF? Maybe mistake?
- Why 40Vpp at TX? Is it necessary?
Any benefit from it? Does this affects RX, saturate it? All the time i am wondering about how it would perform with original coil?
If there is no special benefit from it; than whole MC34063 stage can be replaced with something simpler and less noisy and TX supply can go down to 12V.
- L1 ferrite transformer? What kind? Hand made or ...?
- 79L05 or 79L08 ? Have you compared to see differences?

[WM6]

If you have electronic fixed to coil holder, it is not needed, but i am testing my detectors with electronic in separated case, moving of cable make troubless.

Good to know. I prefer belt-mount detector box too. Thanks.

What of different info can you get from this:

"signal strength can be evaluate with AM or VCO tone."

Is it usable in some sort of target identification?

[Davor]

Sure, especially if you are deaf as a post
Honestly, it seem as a very good idea.You can chose whatever pleases you or both.

[ZdenekHQ]

Interesting!
I have few observations/questions;

- C36 is noted as 1000uF? Is it 1000uF or 100uF? Maybe mistake?
- Why 40Vpp at TX? Is it necessary?
Any benefit from it? Does this affects RX, saturate it? All the time i am wondering about how it would perform with original coil?
If there is no special benefit from it; than whole MC34063 stage can be replaced with something simpler and less noisy and TX supply can go down to 12V.
- L1 ferrite transformer? What kind? Hand made or ...?
- 79L05 or 79L08 ? Have you compared to see differences?

Bigger TX = bigger depth with good coil or same depth with worse coil. For example I have detector with TX amplitude around 200Vpp, it is classic serial LC resonance with rectangle driving.

C36 is 100u, but no problem with 1000u, it is only about space.

L1 - it is ferrite choke with 130 turns of 0.2mm wire : http://www.tme.eu/html/CZ/tlumivky-s..._CZ_pelny.html or http://www.tme.eu/html/gfx/ramka_998.jpg

79L05 or 79L08 - it is all about power consumption, there is no difference for sensitivity.

With VCO or AM you can only estimate a target shape or depth. I dont use it, I like one tone with meter, it is enought for me. Good target make long pure tone, worse target make a "strike", ferrous dont make any tone.

[ivconic]

Bigger TX = bigger depth with good coil or same depth with worse coil. For example I have detector with TX amplitude around 200Vpp, it is classic serial LC resonance with rectangle driving.

C36 is 100u, but no problem with 1000u, it is only about space.

L1 - it is ferrite choke with 130 turns of 0.2mm wire : http://www.tme.eu/html/CZ/tlumivky-s..._CZ_pelny.html or http://www.tme.eu/html/gfx/ramka_998.jpg

79L05 or 79L08 - it is all about power consumption, there is no difference for sensitivity.

With VCO or AM you can only estimate a target shape or depth. I dont use it, I like one tone with meter, it is enought for me. Good target make long pure tone, worse target make a "strike", ferrous dont make any tone.

I still don't understand about choke? Do you use 2 of those or just one?
On schematic i see two coils sharing same core. On photo i see single choke.
So; are those 2 chokes or one with 4 leads?

[ivconic]

There are pretty interesting parts in your schematic, as i said before.
Yet, your schematic is pretty uncomfortable for me to watch and analyze, so "i did it my way..."

[ZdenekHQ]

I still don't understand about choke?

Coil A is "original" choke and coil B (L2 on picture) is wind over it and fixed with glue. See next picture. Its easy.

[ivconic]

Coil A is "original" choke and coil B (L2 on picture) is wind over it and fixed with glue. See next picture. Its easy.

I see! Now i understand! Thanks!

[ZdenekHQ]

Yet, your schematic is pretty uncomfortable for me to watch and analyze, so "i did it my way..."

Good job.

For the first look I am missing R68 in modulator and your C11 (my C12) is too big. It is not universal value, it change phase parameters of your coil and sometimes can kill your discrimination. Because every coil is original, you must test good value, many time is between 1N-10N or not used. I made "coil anaylzer" for it, it is only "hobby" version now, but working good: http://www.hq-elektronic.eu/coil_an.html

[WM6]

I made "coil anaylzer" for it, it is only "hobby" version now, but working good: http://www.hq-elektronic.eu/coil_an.html

Hi Zdenek, thanks for "coil analyser" project. It is not clear to me to which o-scope input we need to connect analyser outputs RX, TX and FAZE. Do we need a multi-channel scope?

Further: how to use four (4) RX inputs of analiser? Aha, on bigger resolution version of scheme it is more explained.

I translate something but is stil unclear:
http://www.microsofttranslator.com/b...u/coil_an.html

[ivconic]

Yes there might be few misses and mistakes that i made. I did it only to easier can see "global picture" of your work, not to use for any further works.
If i decide to make it; i will use your pcb design, because it is proven and more secure choice for me.
About values, yes i had few doubts about values, couldn't decipher is it "nano" or "micro", "K" or "R" for example...
I printed your schematic and than looked in to it while drawing. Was lazy to open your file, magnify it on screen and check those few values.
So, i did it only to clearly see blocks and paths, no other reason.
Cheers!

[ivconic]

Yes, C11 (C12) is not universal value, i agree. Must be chosen carefully in process of testing detector and coil.

[ZdenekHQ]

About coil analyser - you dont need a scope. Only connect TX coil (with detector oscillator running) and RX coil WITHOUT PARALEL CAPACITOR connect to coil analyser. Switch PR1 to NASTAVENI (setting) and with RP1 set max level on meter MP1 (it is about 7.5V, set full deviation). Full deviation of MP1 is 180°. Then you switch P1 to MERENI (measure) and then you can read phase shift between TX and RX. With non-ferous material near the coil must deviation INCREASED, or you need to swap RX wires.