TGSL Tuning & troubleshooting

[golfnut]

Oh, ok I had thought they were modes of operation !

So simple tone selection for acoustic preference then.

Steve

[silverdog]

All getting on with IGSL kit. PCB complete - 4.7uF bipolars arrived off the bay and are in.

orderd a case and bits to complete.

One thing i did not consider from schematic is D1 D2 and the 3 pins of U2 called 'choice'


what do we do here a multiway switch? anyone got a sketch i can follow

steve

These are your choice of tones for the 2 channels, you can use any 2 depending on your preferance for a high or low tone
I think I had D1 - pin9 and D2 - pin 5

[golfnut]

IGLS modes

All getting on with IGSL kit. PCB complete - 4.7uF bipolars arrived off the bay and are in.

orderd a case and bits to complete.

One thing i did not consider from schematic is D1 D2 and the 3 pins of U2 called 'choice'


what do we do here a multiway switch? anyone got a sketch i can follow

steve

[Mullihaka]

How critical is the GEB adjustment?

In other words: does the GEB adjustment need to be a 10-turn pot?

I saw dfbowers to mention in the "Volksturm" thread, that he uses 10k pot for the GEB modification he made.

How about in TGSL?

[ivconic]

Its all very interesting stuff - seems to get you hooked pretty quick.

I really would like to see if there are those amongst you who think the IGSL is a good tool in the field.

Approx is a 12" Air test an approx 6" soil test?

Steve

IGSL earned me 110e already!
List back IGSL topic and find photo of silver coin i discovered the other day (50e)...
Also, already earned me another 60e for ancient roman trader weight i also discovered the other day. I didn't shot the photo of it....
It is just good as any other descent DIY detector.
Advantage could be two tones feature which tells you more infos about the target.
Less digging....or more digging, because IGSL will not shut up in situations where iron is placed near the coin.
And there are more examples, but i named them already on IGSL topic.

[golfnut]

Its all very interesting stuff - seems to get you hooked pretty quick.

I really would like to see if there are those amongst you who think the IGSL is a good tool in the field.

Approx is a 12" Air test an approx 6" soil test?

Steve

[simonbaker]

Cheers for that, another piece of the puzzle cleared for me.

I dont understand how it all works - I would like to.

There are lots of diodes as feedback on the op amps what is that config - A limiter or some such?

Steve

I believe you are right. You can sometimes see the effect on the LM308 output I think. Earlier stages hardly take effect I think. Maybe makes faster recovery.

-SB

[simonbaker]

Hi Simon

Which is ironic because it's actually the E field that moves the current...

This is true on the Tx side - the drive volts into coil gives rise to the current flow in the coil. The alternating current creates an alternating magnetic and voltage fields - We sheild the E portion, leave the mag H part. The H - mag portion too would dissappear if the screen was closed.

The reverse is true for the Rx.

If you didnt null, the Tx field would magnetically couple in phase, (like a transformer)this alternating magnetic field coupled int the Rx coil passes thru the Rx coil windings inducing a voltage on the rx coil output terminals - In line with what you mention simon.
Steve

I think we're talking about two different electric fields, which is OK, my point was trivial anyway.

I think you are referring to the voltage across the TX coil and possible capacitive coupling to the RX coil, which is interesting because I hadn't really thought much about that coupling and the use of the shields for that. Most people talk about shields purpose regarding wet grass static, etc.

With a USB cable we have similar coupling possibilities I think (which der_fisherman likes to reduce with a double-shielded cable).

I will think more about such voltage coupling and the effect of the shields. My experience has been that I usually get a smaller null without shields, which made me think such voltage coupling is not an issue to begin with. But worth thinking about.

Regards,

-SB

[golfnut]

Cheers for that, another piece of the puzzle cleared for me.

I dont understand how it all works - I would like to.

There are lots of diodes as feedback on the op amps what is that config - A limiter or some such?

Steve

[ivconic]

IGSL.

The Tx cct is a colpitts oscillator an runs a frequency 14.6khz (from schematic)

The Rx coil with tuning caps on scehmatic runs at 16.28khz

For best sens should these Tx and Rx be on the same frequency


Confused

Steve

No. It is off resonance setup.
Relation you noticed is exactly the proper one.

[golfnut]

Gettig the Rx coil to frequency

IGSL.

The Tx cct is a colpitts oscillator an runs a frequency 14.6khz (from schematic)

The Rx coil with tuning caps on scehmatic runs at 16.28khz

For best sens should these Tx and Rx be on the same frequency


Confused

Steve

[golfnut]

Hi Simon

Which is ironic because it's actually the E field that moves the current...

This is true on the Tx side - the drive volts into coil gives rise to the current flow in the coil. The alternating current creates an alternating magnetic and voltage fields - We sheild the E portion, leave the mag H part. The H - mag portion too would dissappear if the screen was closed.

The reverse is true for the Rx.

If you didnt null, the Tx field would magnetically couple in phase, (like a transformer)this alternating magnetic field coupled int the Rx coil passes thru the Rx coil windings inducing a voltage on the rx coil output terminals - In line with what you mention simon.
Steve

[golfnut]

2 questions ..

1) has anyone got a link to a youtube vid of someone using an IGSL - not bench testing -but using it in the field. Is an air test approx Double what you get in soil?


2) where do you put your scope/meter during nulling?

Thanks Jerry - didnt see that first time around.

Any feedback for these as a practical detecor - or are they just an ineresting project perhaps? Playing devils advocate

Steve

[golfnut]

4u7 non polarised

I got some of these ordered

http://www.ebay.co.uk/itm/4-7UF-35V-NON-POLARISED-ELECTROLYTIC-CAPACITOR-10-PACK-/120551075888?pt=UK_ConsumerElectronics_SpecialistRadioEquipment_SM&hash=item1c11677030

[ApBerg]

Hey folks.....I know this may be a bit out of bounds but if you guysthink so I'll delete this post.
In the states the 4.7 NP cap is difficult to find cheaply. Not so in Britain for some reason.
At least thats been my experience.
I stumbbled on some in the fee bay site a few months ago that were 20 for $5 with free shipping. I thought I had nothing to loose so I just ordered them. I was pleasantly surprised to find them in y mailbox with in a week even though the seller was from China!
I have posted here over enough years for you guys to know that I am in no way associated with the seller. But I am providing a link to the guys ebay store in the hopes someone else has the same good luck I had with this seller.
I opted to pay 3-4 dollars for the guys expedited shipping instead of his free shipping that he offered.
Only you can decide but here is the link.
If I am out of line let me know and I'll remove the post.
http://www.ebay.com/itm/20pcs-Panaso...item3366ff3418

Thanks ! nice cap's !

Best regards.

Ap