Reg Mods Update

[Cascade Steven]

As an  outsider, I am reading this thread with interest.  A question out of curiosity:  is it possible to provide a simple schematic diagram showing the parts and values used and the attachment points on the circuit board?  I know it would help me understand.   Thanks.

[Jim in Idaho]

11 hours ago, CaliGold said:

Thanks Jim

Completely lost as to what that means tangibly. I know you guys are trying to educate me, but I think I need direct orders. soooo, Solder a 1k resistor in-line somewhere along one of the two wires going to the toggle switch between the two test points? I'm basically gonna solder one wire to Test Point 2 and another wire to Test Point 31 and  neatly route and connect those two wires to the two different tabs on the bottom of this switch in photo below. I'm clueless as to where to put a resistor in this scheme. I ordered these 0805 resistors and sounds like they are the wrong kind. I'll have more time tomorrow to take crack at it. I just put that resistor on top of the cap in photo to show scale. Why God Why.

 

Thanks

Pat

resistor can go on either side of the switch, Pat. Solder one resistor lead to switch, and the other to one of the wires. The resistor is in series with the switch. So TP2, resistor, switch, TP31. OR, TP31, resistor, switch, TP2.   Doesn't matter.

Jim

[Geotech]

Here is a diagram for clarity. I've labeled components both for the SL and the [TDI/TDIpro]. Note that only the SL has test points.

I have never tried this mod so I don't know what the results will be. The purpose of C42/R75/U7d is to eliminate DC offsets and reduce bounce-back noise but maybe it's overkill. If all you want to do is short C42 then I recommend lifting pin 10 of U7 [or removing Q16] or cutting the trace.

 

[Cascade Steven]

Geotech: 

Thankyou very much for the schematic  and also your thoughts on the mod.  Much appreciated.

[CaliGold]

3 hours ago, Geotech said:

Here is a diagram for clarity. I've labeled components both for the SL and the [TDI/TDIpro]. Note that only the SL has test points.

I have never tried this mod so I don't know what the results will be. The purpose of C42/R75/U7d is to eliminate DC offsets and reduce bounce-back noise but maybe it's overkill. If all you want to do is short C42 then I recommend lifting pin 10 of U7 [or removing Q16] or cutting the trace.

 

Thanks Karl! and @Jim in Idaho The metal detector Gods have spoken...

 

pat

[Melano87]

15 hours ago, CaliGold said:

You did not use a resistor? This mod is stumping me. I've been told all sorts of tech stuff I don't understand. "across" "covers" "opamp abuse". Thanks

Sorry for the response time.

No, I had exchanged with several people, and I had not installed a 1k resistor in series.

And I use it like that.

Is this a mistake?

On air tests with modified battery (4x18650) fully charged, I get with the activated switch an additional difference of 5 to 10 cm depending on the type of target.

I did not make the modifications on the capacitors (C20/C21) because Carl had confirmed on a post that if we changed them, we gained in sensitivity but we lost a little in depth.

[CaliGold]

1 minute ago, Melano87 said:

Sorry for the response time.

No, I had exchanged with several people, and I had not installed a 1k resistor in series.

And I use it like that.

Is this a mistake?

No worries. I'm sure we all have lives outside looking for treasure...

 

Do you notice and depth increasing on signals with this mod? Sensitivity to smaller targets? Please share your thoughts  on the performance you've notice if possible.

 

Geotech recommends a 1k resistor in series with the switch to the test points. Learning as I go..

many thanks

Patrick

[Melano87]

33 minutes ago, CaliGold said:

No worries. I'm sure we all have lives outside looking for treasure...

 

Do you notice and depth increasing on signals with this mod? Sensitivity to smaller targets? Please share your thoughts  on the performance you've notice if possible.

 

Geotech recommends a 1k resistor in series with the switch to the test points. Learning as I go..

many thanks

Patrick

As I wrote on the post before, the gain in depth is undeniable and even surprising. For small targets I can't say because I don't hunt gold nuggets, I use it on the beach and on the ground for coins, jewelry etc.

On my TDI SL the mods performed are:

- C56/D20/D21

- C42 switch (without the 1k resistance)

- Potentiometer for the volume

- Battery 4x18650

The one not performed is the one on C20/C21 because I do not want to lose depth.

Carl is the best placed and most competent to talk about the TDI SL.

So I will add this 1k resistance.

Being in France on low mineralized lands compared to other countries, the results may be different.

[Jim in Idaho]

6 hours ago, CaliGold said:

Thanks Karl! and @Jim in Idaho The metal detector Gods have spoken...

 

pat

Thanks, Pat, but don't confuse my tiny bit of knowledge with Karl's far great ability. Compared to him, I'm a hack with a small bit of experience with one particular detector. We're very fortunate to have him to explain all this to us, and I, for one, am grateful.

Jim

[Jim in Idaho]

9 hours ago, Geotech said:

Here is a diagram for clarity. I've labeled components both for the SL and the [TDI/TDIpro]. Note that only the SL has test points.

I have never tried this mod so I don't know what the results will be. The purpose of C42/R75/U7d is to eliminate DC offsets and reduce bounce-back noise but maybe it's overkill. If all you want to do is short C42 then I recommend lifting pin 10 of U7 [or removing Q16] or cutting the trace.

 

Karl, I'm curious about what controls U7d? Thanks.

Jim