Goldscan lV PCB

[Lake]

Bottomside photo?

Could someone who has working unit send a photo of bottomside so I can check the SMD-resistor placement.

[erolunall]

Hello

I saw russian forum about errors on gs4 please look
http://md4u.ru/forum/viewtopic.php?t=982

Regards
Erol

[barry]

I have been playing with parts of this circuit in LTspice to understand how it all works. I have noticed U8 and U9 do not trigger there outputs (Q). Is the circuit correct for U8 and U9 ?

Note: U7 and U5 are functions as expected in LTspice.

[porkluvr]

You are probably looking a schematic from Alexismex? Those ICs are correctly wired. It is easy to make a mistake editing (or wiring) the 4538s. If the other 4538s seem to work make sure the attributes of the two "bad" ones are edited in the same fashion. (Deleting, then cut-paste from known good is sometimes quickest.)

Make sure the RC "R" goes high (R19, R20 to ground). "C" qoes low (C19 to -12V) and RST\ (3,13) go high .

There are more than one version of GSIV schematic so let us know which one you are looking at if you still have a problem.

It runs like a top if it is wired correctly, but as you have probably found out, things can be slooow with 4538s in the picture.

[Alexismex]

Ello Lake,
-sure it is a inductor of 47mH
The 4538's wiring in my schematic is OK 100%
Have a good day
Alexis

[porkluvr]

retraction

Here's where I get to admit that I gave some messed up advice at some time in the past (right at the top of this page). I took a look at the GS4 charge pump (+5V generator) and did not think it would work because there is no obvious bias path for the switch transistors. And then, I "tested" it.

Well, as I was "testing" the circuit (in my virtual laboratorium) I think I had the 1k and 39k oscillator resistors (at LM555-7) reversed. Doing that, the 555 duty-cycle ran at about 4% and the voltage output was not very impressive.

However, swapping those two resistors - in accordance with the existing GS4 schematics, makes the charge-pump work very well. In fact it seems to work more efficiently than other similar circuits with "obvious" bias paths.
What can I say? It looks funny, but works OK. I've been wrong before and I'll probably be wrong again, but that was wrong!

[Eugene52]

Goldscan IV PCB

Hello Porkluvr and Happy New Year !!! I thought this GS-4 was a perfect working and Final Tested Machine ????But , maybe you are Right !!! The 1 k is drawing to much current , making "TS-555" un-stable or is that LM-555 ?? Are they an identical substitute . Are you talking about the 80 khz switching power supply you pictured above ??? Your new simulation software might be correct for LM555 , not TS-555 . The pdf schematic from page 1 on this thread just says 555 . So , It looks like you will make this better . No offense to Eric of course...Please let us know what you find !!............Regards.....Eugene

[porkluvr]

Hello Porkluvr and Happy New Year !!! So , It looks like you will make this better . No offense to Eric of course...Please let us know what you find !!............Regards.....Eugene

You misunderstood what I was trying to say. The original +5 generator is perfect. But, when I was trying to "test" it I wired it incorrectly!

Just remember not to switch the 1k and 39k resistors by mistake. Don't do like I did!

[Eugene52]

You misunderstood what I was trying to say. The original +5 generator is perfect. But, when I was trying to "test" it I wired it incorrectly!

Just remember not to switch the 1k and 39k resistors by mistake. Don't do like I did!

Cool , I understand now. It seems like you are thoroughly Testing your software . For me to do that I have to upgrade my computer , I tried a simulation software a few months ago and it froze up on me . I will try it again later , when I have more time.....I was just interested about your post here today , because schematic errors on Geotech are not un-common ...False alarm...........Regards....Eugene

[barry]

In the circuit I am modifying I have changed the voltage pump to a 7660 to reduce component count. I am going to replace the main timing 555 and all the 4593's with a micro. Also looking into changing the front end op amp to something more modern with less noise.

[ronmann]

has anyone made a sm pcb

[kadir6141]

gs IV

Can to send for me.

[Dean Sarelius]

Greylaurie recommended I take a look at the new Goldscan in his own words "Posts by Max, Reg and Jose' give lots of tips on constructing what is in effect, the predecessor to the TDI."
I have seen the video clip on youtube below and I am very impressed with the performance so am keen to build what appears to be a PI which can provide some discrimination and ground rejection..!
Does anyone know how I can get my hands on a PCB of the Goldscan IV as I would really like to build for testing..?
http://www.youtube.com/watch?v=GEd9_...ature=youtu.be
Cheers
Dean

[sinclairuser]

unless one of the lads had some boards made(and will let you have one), you will have to make your own i'm afraid.

[Orbit]

goldskan 4 u sprint lajut 5.zip