GOLDSCAN 5 SCHEMATIC QUESTION

[peyman 74]

hello , if we increase the tx pulse with , is it possible to use a larger coil ?

[daverave]

you dont need to increase the tx pulse...you will drain your batteries a lot quicker....i made a 12" & 14" coil and my 14" coil has already gained a few inches in depth without touching the tx pulse.

[peyman 74]

have you a idea to increase the deep in device to work very well with large coil?

[peyman 74]

pcb that abanner(v13) put here someone made it ? is it correct ?

[6666]

you dont need to increase the tx pulse...you will drain your batteries a lot quicker....i made a 12" & 14" coil and my 14" coil has already gained a few inches in depth without touching the tx pulse.

Hi Dave, I have a 2003 pound coin, what sort of distance would you get that coin with your 14 inch coil ? thanks.

[DonCaffeDelaSkobalj]

Hi all

gScan_5 isn't definitely nugget hunting machine. Repetion rate is to low, Tx forward phase to long. Togetheer with non properly designed Tx stage AND non corectly choosen MOSFET is a main source of overheating damping resistor and great ammount of integrated noise in post-processing stages. Also a current consumptionis is to high for this class of PI machine.

As it was initially Eric design, i suggest newest Eric's TIME CODE 12-4-4-4-4 for the real NUGGET HUNTERS. It isn't an easy task.
Also GB timing must be tweaked on the highly mineralised ground. This all worth for mono pulse design. Further design for example gScan 6 should be bipolar nugget PI machine.

Regards
Don

[Ferric Toes]

Hi all

gScan_5 isn't definitely nugget hunting machine. Repetion rate is to low, Tx forward phase to long. Togetheer with non properly designed Tx stage AND non corectly choosen MOSFET is a main source of overheating damping resistor and great ammount of integrated noise in post-processing stages. Also a current consumptionis is to high for this class of PI machine.

As it was initially Eric design, i suggest newest Eric's TIME CODE 12-4-4-4-4 for the real NUGGET HUNTERS. It isn't an easy task.
Also GB timing must be tweaked on the highly mineralised ground. This all worth for mono pulse design. Further design for example gScan 6 should be bipolar nugget PI machine.

Regards
Don

Hi Don,
Goldscan5 was developed for nugget hunting as well as for beach hunting. Previous Goldscans had effective ground cancellation based on a development of mine in 1983 after a visit to Australia and which resulted in Goldscan 1. However, there are certain goldfield areas in Victoria, Australia, where the ground effect is particularly strong. Modifications were made along the line which culminated in Goldscan 5, A B, and C. with improved ground cancellation. The design was sold to Whites and continued with further upgrades to the TDi Pro and SL. and finally the TDi BeachHunter. I continued with Goldscan 6, which was a much more powerful detector designed for larger nuggets more deeply buried. Tests in the Victoria Goldfields were made and it proved to have a advantage over the competition in this respect. Introducing detectors in Australia that compete with home grown ones is an uphill struggle fraught with legal challenges, so the project was discontinued, although the methods I have used in cancelling viscous remanent magnetism (VRM) in the soil or rock predate any patents subsequently lodged for PI detectors.

As to the detector I have that runs on the 12-4-4-4-4us ,timing, even if GB were added, would only be of use for fly spec nuggets. The range on the larger bits would be poor, as the Tx pulse is much too short and too small in amplitude. VRM has a different decay law to conductive targets and increases dramatically at short delays, and that could be a big problem. This proportional timing is useful though and has been used in a prototype nugget hunter where we have,say, a useful Tx of 50uS and upwards; and succeeding proportional delays and samples all under the control of a variable clock generator.

I agree that bi-polar pulse technology would be the way to go for future designs. It would also eliminate the small hysteresis effect that has been observed in some VRM studies.

Eric.

[DonCaffeDelaSkobalj]

Hi Don,
Goldscan5 was developed for nugget hunting as well as for beach hunting. Previous Goldscans had effective ground cancellation based on a development of mine in 1983 after a visit to Australia and which resulted in Goldscan 1. However, there are certain goldfield areas in Victoria, Australia, where the ground effect is particularly strong. Modifications were made along the line which culminated in Goldscan 5, A B, and C. with improved ground cancellation. The design was sold to Whites and continued with further upgrades to the TDi Pro and SL. and finally the TDi BeachHunter. I continued with Goldscan 6, which was a much more powerful detector designed for larger nuggets more deeply buried. Tests in the Victoria Goldfields were made and it proved to have a advantage over the competition in this respect. Introducing detectors in Australia that compete with home grown ones is an uphill struggle fraught with legal challenges, so the project was discontinued, although the methods I have used in cancelling viscous remanent magnetism (VRM) in the soil or rock predate any patents subsequently lodged for PI detecelopeoftors.

As to the detector I have that runs on the 12-4-4-4-4us ,timing, even if GB were added, would only be of use for fly spec nuggets. The range on the larger bits would be poor, as the Tx pulse is much too short and too small in amplitude. VRM has a different decay law to conductive targets and increases dramatically at short delays, and that could be a big problem. This proportional timing is useful though and has been used in a prototype nugget hunter where we have,say, a useful Tx of 50uS and upwards; and succeeding proportional delays and samples all under the control of a variable clock generator.

I agree that bi-polar pulse technology would be the way to go for future designs. It would also eliminate the small hysteresis effect that has been observed in some VRM studies.

Eric.

Thank you Eric.

There exist methods for improving amplitude of very short Tx pulse as is in 12-4-4-4 timing, for hunting larger bits of gold in Oz's soil. Not to complex modifications of Tx frontend will boost amplitude till 100 КWt in peak pulse power, ordinary at 50 ohms load or lower. Methods were widely used in particle accelerators.

Do you have envelope for VRM dacay law for golden areas in Victoria, Australia ? Variabile Tx pulse train inside main Tx pulse while keeping your inicial 12-4-4-4 timing code with super fast ns pulses integrated in main Tx pulse with properly set duty cycle. I think envelope of complex Tx excitastion curve, should follow inverse law of VRM decay curve, or maybe pseudo inverse. The best would be tests on a real Oz soil. Also amplitude boost should be controlled up or down to keep oversaturation of very small nuggets end eliminating soil hysteresis.

Regards
Don

[DonCaffeDelaSkobalj]

Hello Eric

You can contact me via e-mail if you want. We can talk about new input frontend with your time-code 12-4-4-4. All your designs are very good. We could improve input stage and rx stage, while keep your original design. About Rx at nano seconds time frame,OP slew rate and settling time are two opposite stuffs. I would point out for improving settling time, because we have deal with nanosecond pulses with very sharp front and back eadges and very fast transients.

Regards
Don

[Orbit]

:лол:

[Ferric Toes]

Hello Eric

You can contact me via e-mail if you want. We can talk about new input frontend with your time-code 12-4-4-4. All your designs are very good. We could improve input stage and rx stage, while keep your original design. About Rx at nano seconds time frame,OP slew rate and settling time are two opposite stuffs. I would point out for improving settling time, because we have deal with nanosecond pulses with very sharp front and back eadges and very fast transients.

Regards
Don

Hi Don,
Thanks for your offer of private discussions. Yes, improvements can be made in many aspects of PI detectors and instrumentation. For my part, I am already working on some of them; one being my Mk2 version of the Magnetic Viscosity Meter, MVM2, which has proportional timing all the way up tp 1mS Tx pulses. With the MVM I am able to plot magnetic decay curves with great accuracy, which will be useful when improving PI detector designs for nugget hunting. I have rocks and soil from many different countries, including Australia, which incidentally, exceeds anything else I have for VRM. This and two other projects are running behind schedule for various reasons, so I must concentrate on them and hold fire on doing any additional design work. I help out where I can on forum discussions but that has to be my limit at present and for the foreseeable future.

Eric.

[DonCaffeDelaSkobalj]

Tanks you Eric.

I hope you will be lucky with Australian rocks.

Regards
Don

[Orbit]

Another version of the TDI -PRO with a new controller !

[daverave]

did you design this TDI..Orbit ???

[Orbit]

Of course,and now I'm drawing a TDI -SL original, I intend to draw several versions, one will be with bipolar transmission similar to fisher impulses!
otherwise on the drawing is TDI -PRO except I use my controller and little modification in the power supply and I don't use an integrated circuit for sound as with pro already from the TDA family- ....I can set different times with my controller and a frequency of 800hz to 3.3khz..I have drafts of several versions from the original to my modifications which mainly relate to noise reduction!