LOOKING FOR GOLDSCAN 4 Schematic.

[Unregistered]

Goldscan4

Hello, I understand your frustation , first for me I have this doubt also , i check the original board many times to see if the pin 1 and 15 of "D" does connect to the pin 1 and 15 of "C" but it do not physically 100% shure of that...
I say ok , but i will remember this bug when i check my board specialty the timing circuit with my scope ...when i finish my first printing board i doble check it and with some minor adjustment all the circuit did work like the original ,same range detection etc...
I also connect and disconnect the "BUG" nothing happen in the scope , like I say????????????????,same timing sequence etc...
For me it will be easy because i can check all the originals signals from the original GS4 because I have it and i compare with my signals of my board also , i make the same coil with very near the same inductance and resistance ...It is for that reason that i tell you that , yes i pass many many hours to reverse , because of the doble board etc..and also without destroy the original (it still working...) Sometimes you don't understand something in electronic design but it work ....Like i said before, to convince you, it is better to take a proto board and make only the timing seccion and you will see the four beauty signals(15uS) at pin 6 and 10 of "D" and at pin 6 and 10 of "C" and their sequence; I note them with TEST.
You will need 555, and four 4538
Resistors( for 555): 10R ; 6K8 ; 47K ; pot frequency 10K
condensator(for 555): 47N ; 22uF
NOT to much with this you have a pulse from 450-550PPS...
NEXT for the 4538'S :
resistors: 10R;5K6;27K;39K;120K;120K;8K2;1K2; trim:10K;Pot delay:50K
Condensator:22uF;1500pF (X5); Diodes:1N914(X4)

IN TOTAl ONLY 11 resistances, 8 condensators; Two pots, one Trimmer and 4 diodes ;one protoboard and one hour of work...Remenber the GND of the GS$4 it's connect to the POSITIVE of your alim (see schematic)...
I do not ask you to much time and money to check this , OK....
And if you continue your effort you put a IRF 740 ;a 2N3906 and a Op 709 o another, a coil, and you have your front end set up.........

The only error you will have in the schematic it is : put the drain of the two J113 to GND (1/4 IC2 ) like they say in the forum and open the connection of POT SENS in IC3..... the second error is not too much and easy to see but the first error was too bad and the detector do not work ...my apology for that ....all the schematic is the same like original....
Have a good night,
Alexis.

[Cadophobic]

Made a mess

Alexis (and Everybody):
I have decided that the that the 4538 spice "model" that I used is definately inaccurate. I took issue with the Goldscan IV circuit showing two instances of where an OR gate's (+) inputs would be held high, and wondered about how the associated outputs could ever change in that configuration. And, while I still wonder about that, I can see that the so called "fix" that I offered has, apparently, no less than seven (7) counts of the exact same offense. I had doctored the CD4538's diagram without fixing any problem with the actual model or even attempting to understand its sublties.
Do not trust my timing diagram. The IC model was probably derived for a 74123, although the circuit diagram does not match. I need more time to sort this out.
Whhooee, what a mess.
Back to the drawing board for me! I may come back if and when I ever sort this discrepancy, but meanwhile you can color me red! I will attempt to correlate my theory against real-life, in the meantime. (Eerch).


Sorry about any confusion I have caused.

[Cadophobic]

retraction

Let me pour some more gasoline on my argument about why Alexis' reverse engineered drawing won't work.

I believe the CD4098 device is -essentially- the same as a CD4538. A datasheet available from
http://www.st.com/stonline/products/...re/ds/2071.pdf describes a non-retriggerable mode for the device, where, (Q) and (+in) should be connected together if negative edge triggering.

This would account for the configuration of TC4538-C and D.

(Looks like I get a full plate of crow today.)
However, National suggests grounding pins 1 and 15 to pin 8 (big deal).
Cadophobic

[kt315]

hi All. again and again, people worry that the topic may be get out! and get out at the bottom! GOLDSCAN-IV!... I attach new one here I got from camraden. I VERY hope you are ready to help us to verify and to fix it up.

all the Best.

[Alexismex]

verif

hello 315,
I check quickly the schematic , my two errors are corriged :
- pot SENS is now ok and q9 and q10 go to the ground ...

The big FORGET it is the tank condensator 3300uF connected between r11+r12+source of q4 ...to the ground ...OK, please make the change in schematic.
it is very important to have this condensator .
For the 5534 (work very well also), but i have another configuration WITHOUT the cond.of 10pf ...
Now i do not much time but i promess to publish the photos of my copy of the original boards exactly like i see them.
Have a good day
Alexis.

[1843]

Gold Scan IV

Hi Alexismex,
Why do you miss your time by drawing the schematic? It is not important...
Please design a one side PCB for it, It is very very neseccary!

Best regards

[Chris2]

Gold Scan IV

Hi 1843,

be patient....drawing a proper schematic in a CAD program is the first step in making PCB's. Chris

[1843]

Hi 1843,

be patient....drawing a proper schematic in a CAD program is the first step in making PCB's. Chris

Hi chris,
one side pcb is good!

[Reg]

There is another error on the schematic and that is located at the input to the preamp which is now a NE5534 (was a LM709 on the earlier schematics). The two diodes connected to pin 2 are shown as a parallel set. One of the diodes needs to be reversed. In other words, the input pin of the op amp will connect to the cathode of one diode and the anode of the other. This will allow the diodes to limit both positive and negative voltages.

Reg

[Unregistered]

[QUOTE=Chris2;49218]Hi 1843,

be patient....drawing a proper schematic in a CAD program is the first step in making PCB's. Chris [/QU
I NEED PCB FOR GOLD SCAN 4

[sisco]

Hi all

have somebody GOLDSCAN4 PCB layout with standard parts (not use SMD

parts like GS-4 pdf file)

[Geo]

Hi Sisco.
I never saw a pcb with standard components for the GS4 on this or to another forum. I think that Max make it with standard components so he can tell us about the pcb.....

[Max]

Hi Sisco.
I never saw a pcb with standard components for the GS4 on this or to another forum. I think that Max make it with standard components so he can tell us about the pcb.....

Hi,
well, I've used standard components but haven't any PCB design, just used protoboards and make a huge mess with separate (shielded) modules.

But after lot of problems I get it work!

I was starting design one PCB, single sided, at the end of testing to make things close and get smaller dimensions (circuit is complicated and bigger than other PIs), very hard work... too just knowing there'll be no sure results cause you know there are geometry problems in this kind of circuits that could cause self-osc etc but then discovered the bad addiction of GS4 with ceramics and gave up on this.

After that I switched my attention to bandidoII, then had no time or will for making GS4 clone further improvements...

Now I've just a big black-box and it works... but at the end I've realized was lot of efforts for nothing: can't use in the sites where I need much! Just on the beach... and I don't go so often for beach hunting.

What to say... it's a good PI, but not worth the efforts if you plan to search in places like mine (with bricks, ceramics etc). Think that real use is on the beach or e.g. in uniform desertic goldfields without hotrocks.

Best regards,
Max

[Max]

Hello forum, I am who make the reverse schematic of the Goldscan many years ago , don' t waste your time to tell us it's not working because the complete seccion of timing is 100% OKKKK, for you it is much better to take your solder pen with fumes of flux (better that playing with spice) and realize the complete Goldscan4 and you would see for yourself it work perfectly....please do not spread doubt for the people who want to construct the GS4, it is a very, very good pulse detector with a beautiful engineering design (thanks a gran part to Eric)...I have realize at this time many version of GS with different variation design (audio, autotrack,etc...) but the main seccion for exemple the timing are still not changed ....Very soon I will have a web site with all the infos about and the printed circuit in semi-kit ...
have a good time and goods constructives researchs all guys of the forum.
I do not write many time in the forum because in this moment i am very busy in working.
Alexis.

Hi Alexis,
I know everything you said about schematic is true. I've it working !
There were just little mistakes on fets etc now everything solved.
In an older post there is corrected schematic and also PCB layouts (double side smd).

Thanks again for the posted stuff I really appreciate.

FOR THE OTHERS HERE: timing circuit is OK.
If someone have dubts just play with a 555 and some 4538, you'll see all the right timings of GS on your scope. Thoughts about pins connections of 4538 are just academic ...and circuit work absolutely the same connecting "that" pin or not.

Best regards,
Max

[1843]

Hi Max,

I saw a person that claimed he has maked GS4 that can detect large objects at 5m with 1m x 1m coil!!!

I doubt if GS4 can detect so....!?
Your opinion..?!

Best regards