Goldscan 4 error list....

[Chris]

Hi

After Eric mention that in the main circuit of the Goldscan 4 are a couple of errors I took the challenge to find them....here is what I found (summary):

1) the SENS poti (tap) suppose to be in series to the 1 k Ohm resistor. (mention erlier in the forum)

2) the two diodes (1N414 at the UA709 input suppose to be antiparallel and not parallel connected.

3) mixup in the labeling of source & drain at some of the J-FET's.

and the next point makes not really sense to me. But you can correct me if I'm wrong.

In the reset circuit: What is the reason to switch a second capacitor (100nF) via a N-FET
parallel to a 470nF capacitor? Is there maybe an additional GND or power connection to a reference missing?


Regards
Chris

[alex]

Re: Goldscan 4 error list....

Hello Chris and the Forum:
1) Error in transcribe in schematic ...it's Ok and very easy to see!!!!!!; please sorry everybody.
2) Look and see Chris, I put a note : * Original board design.....BECAUSE in the original board the two diodes have this configuration original .....first make this configuration of this front end , take your oscillo and look the signal, invert one diode ,and see the difference you will understand...why !!!
3) For me , Drain is Drain in concordance in Original board and the physical J113........and I can not make a mistake because of the two identicals channels designs...in the board.
4) because in normal operation the 100N work via drain source of the J113 not to Gnd ,and the 470 N work with the IC2 pin 8 to maintain a charge to slow down the autoreset when a negative voltage of more 10 -15 mV happen....it is my explanation ,and it is the configuration in the original board ,and like i say before : experiment with your protoboard and you will see it WORK perfectly.....
It is good Chris to observing some details , but it is better to make the circuit and see how it work in REALTIME and ask IF the circuit do not work.....because sometimes you want to Help and you prejudice more the people who want to realize the project..........and it is , you call it in Internet jargon misinformations.
Please let this forum continue the big labor and nice work of Carl .....a technical and progressive encounter with sharing of ideas.
And don't worry gentlemen ......it is hard and difficult to realize a good PI detector ??????
Have a nice and productive day with peace in your mind.
Alexis.

[alex]

Re: Goldscan 4 error list....

Hello Chris and the Forum:
1) Error in transcribe in schematic ...it's Ok and very easy to see; please sorry everybody.
2) Look and see Chris, I put a note : * Original board design.....BECAUSE in the original board the two diodes have this configuration original .....first make this configuration of this front end , take your oscillo and look the signal, invert one diode ,and see the difference you will understand...why !
3) For me , Drain is Drain in concordance in Original board and the physical J113........and I can not make a mistake because of the two identicals channels designs...in the board.
4) because in normal operation the 100N work via drain source of the J113 not to Gnd ,and the 470 N work with the IC2 pin 8 to maintain a charge to slow down the autoreset when a negative voltage of more 10 -15 mV happen....it is my explanation ,and it is the configuration in the original board ,and like i say before : experiment with your protoboard and you will see it WORK perfectly.....sometimes in your life you must trust people and if I allready made unit who match exactly with the original ....the schematic it is good 100%.No magic in electronic,the things works o don't work with a small error...
It is good Chris to observing some details , but it is better to make the circuit and see how it work in REALTIME and ask IF the circuit do not work.....because sometimes you want to help and you prejudice more the people who want to realize the project..........and it is , you call it in Internet jargon : misinformations.
Please let this forum continue the big labor and nice work of Carl .....a technical and progressive encounter with sharing of ideas and good peoples.
And don't worry gentlemen ......it is hard and difficult to realize a good commercial PI detector ??????
Have a nice and productive day,ask me if you have some doubt .
Alexis.

[Eric Foster]

Re: Goldscan 4 error list....

Hi Chris,

You are right on all counts. Only on point two was there an error on the silk screen which resulted in one diode being the wrong way round. Fortunately they conducted on the high voltage spike.

Suggest checking the board again Alex on the other points.

Eric.

[FJ]

Re: Goldscan 4 error list....

When I first saw this schematic posted I wondered what you thought about your work being plastered on the internet. You sure are a better sport about it than I would.
FJ

[Eric Foster]

Re: Goldscan 4 error list....

Hi FJ,

It didn't worry me too much. The Goldscan circuitry is a bit dated now and having the schematic is one thing, but it is quite another to know the correct setting up procedure. Some settings are obvious, but others have to be done in a certain way for best performance. Another important factor is the search coil. Any coil will work to some degree, but again, there are a lot of hidden factors.

Being on the Internet, you have to accept that it is a very public place and things sometimes appear that you would rather not. However, the other side of the coin is that I have received a wealth of information and feedback, from users and other engineers, which enhances my development effort and keeps my interest going.

Eric.

[Michel]

Re: Goldscan 4 error list....

Hello,

I was drawing your Goldscan IV schematic in a CAD software when I have read the Eric message.
The two parallel channels and discrimination circuit drawn my attention and seems to be a serious improvment from other non professional designs.
Please Eric do you think that this design is obsolete now ?
You said also that some missing error could affect the performance.
Could you help us about that, please ?
I'm ready to put on this forum my files (sch & pcb) to complete the huge and nice Alex work, but it could be interresting to have technical point of view of the author before we go further.

Best Regards for all,

Michel

[Anatoliy]

Goldscan 4

please need corect shematic & pcb for goldscan 4 please post more information for construcion of this detector sorry for my bad english