Another version of TGSL

[ZdenekHQ]

Hi friends, I am not sure, if it is right section.

Here is my last "mutation" of TGSL with one-layer PCB.

Some futures :

- easy single power 2x Li accu 3.7V/2200mAh (about 15-20 hours of work), or some accu around 6-9V without any unstability.
- all internal switching powers is synchronized with TX for interference suppresion.
- advanced "star grounding" (known from power audio amps), decrease ground feedbacks and unstability.
- designed for DD coils, frequency around 10kHz with phase shift around 90°.
- increased TX power (TX signal is around 40V point-2-point, can be more).
- very narrow, but easy RX filter for better noise imunnity
- better stability of GB and DISC setting without mutual influencing (not used unstable LM393 comparators for phase shifting etc.)
- atypic full wave synchro-detectors for better noise imunnity.
- single tone or two tone target indicator.
- signal strength can be evaluate with AM or VCO tone.
- accu capacity can be measure with VCO or METER, "low-accu" protect with auto-off.
- individual setting of basic tone frequency (independent of TX frequency)
- one layer PCB for homemade production, but no problem to make profi gerber data and drill for one or two layer PCB.
- there is not need to use all functions, can be easy hard-switched on board with jumpers.
- tested and known construction without atypical parts (atypic choke for switching power is easy-to-made)

Schematic diagram is here : http://www.hq-elektronic.eu/data/sab2_sch.pdf

Other materials you can download from my pages here : http://www.hq-elektronic.eu/menu_sab2_vp.html

If you have troubless with Czech language, I can translate it to English or re-upload here.

Good luck !

ZdenekHQ

[scs]

I've done a similar detector. Problem is the slow filter amplifiers.

[satdaveuk]

Hi thanks
Reloaded here in english would be nice, and thank you very much

Regards

Dave

[ivconic]

Hi friends, I am not sure, if it is right section.

Here is my last "mutation" of TGSL with one-layer PCB.

Some futures :

- easy single power 2x Li accu 3.7V/2200mAh (about 15-20 hours of work), or some accu around 6-9V without any unstability.
- all internal switching powers is synchronized with TX for interference suppresion.
- advanced "star grounding" (known from power audio amps), decrease ground feedbacks and unstability.
- designed for DD coils, frequency around 10kHz with phase shift around 90°.
- increased TX power (TX signal is around 40V point-2-point, can be more).
- very narrow, but easy RX filter for better noise imunnity
- better stability of GB and DISC setting without mutual influencing (not used unstable LM393 comparators for phase shifting etc.)
- atypic full wave synchro-detectors for better noise imunnity.
- single tone or two tone target indicator.
- signal strength can be evaluate with AM or VCO tone.
- accu capacity can be measure with VCO or METER, "low-accu" protect with auto-off.
- individual setting of basic tone frequency (independent of TX frequency)
- one layer PCB for homemade production, but no problem to make profi gerber data and drill for one or two layer PCB.
- there is not need to use all functions, can be easy hard-switched on board with jumpers.
- tested and known construction without atypical parts (atypic choke for switching power is easy-to-made)

Schematic diagram is here : http://www.hq-elektronic.eu/data/sab2_sch.pdf

Other materials you can download from my pages here : http://www.hq-elektronic.eu/menu_sab2_vp.html

If you have troubless with Czech language, I can translate it to English or re-upload here.

Good luck !

ZdenekHQ

Good job Zdenek!
There are nice parts in your schematic.
Is there any video demonstration on the net, to see it in action?
Cheers!

[WM6]

Excellent work Zdenek.

http://www.microsofttranslator.com/b....eu/index.html

[ivconic]

MODUL HDM looks pretty interesting to me, according to description available.
Zdenek can you give us here more details?

[ZdenekHQ]

Hi, I dont have any video, it is classic and average detector with some enhancements. I spent long time with "timing" of channels, but it need DD coil with holes for better target locating. It is all about coil. In air test with my DD 26cm I can detect coin 1Kčs (dia 23mm) for about 25-30cm and 80mm target for about 65cm, but in terrain it is a half of this "depth", I was check it.

I dont know, if my friend Zdenek Jarchovsky sent here your patent for new concentric coil, it is much more better than classic construction. In czech language is here, look at the end of patent : http://www.hq-elektronic.eu/data/patent_z_jarch.pdf

HDM is for PI detectors, especialy for JABEL, it can discriminate between good and bad conductivity materials, but for example non-pure gold have same conductivity as ferrous, there is better use the above mentioned patent for ferrous/non-ferrous materials, is it useful for it.

[ivconic]

I see.
Quite interesting coil design!

[ZdenekHQ]

It will need grounded graphite film shielding, but I believe it will be easy to made. You dont need to make complicated small-loop-RX coil, you can make simple TX, RX and six small compensation coils with reversed wiring and connected it with RX coil.

[ivconic]

I will try to translate .pdf in English and than, suppose, i will find answers on few questions there, but
until than; what interests me are differences and advantages of such feedback (bucking, nulling) coil over conventional one?
Is there any special reason why such feedback coil is chosen instead conventional one?

[scs]

Very high factor Q of the TR coil is . How detector works when search at ground?

[Davor]

Maybe too much copper at hand?

Against my better judgement I'll give a few thoughts upon my first impressions.

A PSU will surely create lots of problems to the uninitiated. Unless it is done just perfect it will scream.
An input opamp at ~20nV/sqrt(Hz) on one side, paired with a strong Tx on the other side, reminds me on the general direction of PI development. I'd pick the opposite direction, but this is not my build and I'll not complain.
Using op amps as comparators at audio frequencies is probably not the best way to extract phases. Frankly, there is nothing wrong with the comparators, especially not at that levels.
A choice of full wave switchers is a bit uncommon for metal detectors, jet it crops here and there occasionally. I first saw it long ago in a cave radio solution, but at considerably larger signal levels. There is a problem with offset in this circuit which just may work out because of the motion compensation, and using FET input opamps.
Slowing down GEB channel ... just doesn't compute.
Nice pick for the audio solution. Combining VCO and AM is a very nice contribution.

[golfnut]

Nice and clear - like the naming of each circuit section. Lots of thought up front on this one. Good effort.


Is this really Full wave Demod?



S

[ZdenekHQ]

Hi, I made some changes, please see updated data : http://www.hq-elektronic.eu/menu_sab2_vp.html

Full wave detector can eliminate all stochastic-random noise. You can testing detector and watch CRT TV, there is no interferences. With half-wave it is impossible.

Next picture - there is a RX signal (200mV pp), "detected" signal and "driving" signal from comparator to 4066. TX signal is 40V pp, gain of preamp is 100, so rest signal on RX coil is about 2mV from 40V. There is no problem with TX to RX breakthrough, but better is use external RX pre-amp.

Yes, there is some noise over RX signal, but this is HF noise and static, so can be easy filtered. You can try different OP amps, I was made some tests of it without any distinct change of depth. My most important thing is good stability and easy production.

TP8 is measured with uncompensated probe.



P.S. : This version of VBulletin is terrible....

[WM6]

There is no problem with TX to RX breakthrough, but better is use external RX pre-amp.

Very interesting improvement Zdenek. What mean "external RX pre-amp". Preamp build in coil?