GOLDSCAN 5 SCHEMATIC QUESTION

[daverave]

Re the audio section, i've posted my method a few time on the forum. Here it is again.....

Hi/Lo tone and audio level rise from threshold.

Hi Mickstv....many thanks for your schematic...will this give the same sound as the gs 5/tdi ???? also could a hi/low switch be used if this circuit were used in a gs 5 ????

[mickstv]

Yes that is the schematic I was referring to, thanks mickstv

Aussie Slang..... No worries eclipse

Hi Mickstv....many thanks for your schematic...will this give the same sound as the gs 5/tdi ???? also could a hi/low switch be used if this circuit were used in a gs 5 ????

The circuit will give the same sound as the GS5/TDI. I decided the hi/lo switch was a waste of time, so was never added it. The circuit above was used in my ground balancing PI, for nugget hunting.


EDIT to add a hi/lo switch would require major mods to my existing circuit.

[Orbit]

He will not give the same tone TDI ...No low tone you get a double tone e.g on iron scheme of mickstv but a good design !
Although it will be better Mickstv to explain !

[ionut_mtb]

The discrimination on the GS5 is definitely not ferrous/non-ferrous. It's the same as the TDI, which purloins the ground balance function to give a different audio tone for targets either above or below a particular setting.
http://www.detectorprospector.com/go...n-settings.htm

Verry good article, it makes sense, thank you. The only thing that i don't understand is this:

"Now run a coin or larger steel item within 1 inch of the coil. You will get an overload signal, a strong baaaaawo, baaaaawo. This is the shallow item overload signal. If you are trying a steel or iron item, increase the distance from the coil. Note that at a certain distance it abruptly cuts off. Now try a coin and slowly increase the distance from the coil. It will gradually turn intorc that sweet coin tone. The way you tell shallow coins from shallow junk is to slowly raise the coil. If the target just cuts off – junk. If it slowly mellows out – dig!"


big iron at depth will not have same signal as shallow gold ring? How is making the difference? And also how the signal of iron cut's out completly? Even at depth.

Thanks again

[daverave]

ok thanks mickstv

[mickstv]

Whether it be the GS5/TDI or my PI the circuits are all basically the same, they use delay adjustments to achieve a ground balance point. When ground balance is met, small targets with short TC will generate a higher pitch tone whereas big targets with long TC will generate a lower pitch tone.

Iron reject never works correctly in PI detectors because the TC of any Iron object can change due to things like orientation, size and depth.

The hi/lo switch isn't needed because you cant distinguish a small short TC target in the same location as a long TC target.


Wish I could explain better, but not sure how to put it into words

[daverave]

Hi mickstv...i know nothing about the ground balance on the gs 5/tdi and its something i would like to learn about it...all i know is that it uses another sample...if the switch is not needed then i will maybe forget that...im happy if i can get a high and low tone i looked on the internet for the opa 1642 and i could only see surface mount type which i guess would need an adaptor...your diagram has really en courged me to try and make this gs 5....i appreciate your help very much

[eclipse]

Op amps are not that important there

[daverave]

Op amps are not that important there

Hi eclipse...can any dual op amp be used ???

[mickstv]

Hi mickstv...i know nothing about the ground balance on the gs 5/tdi and its something i would like to learn about it...all i know is that it uses another sample...if the switch is not needed then i will maybe forget that...im happy if i can get a high and low tone i looked on the internet for the opa 1642 and i could only see surface mount type which i guess would need an adaptor...your diagram has really en courged me to try and make this gs 5....i appreciate your help very much

Hi daverave, as eclipse posted any other opamp could be used, like the good old TL072. Don't go wasting your money on any opa1642's until your happy with the design.

[daverave]

Is it best to give the audio circuit a separate power supply and maybe put the audio section into another box separate from main circuit maybe to help reduce any noise ?????

[eclipse]

Dave the power supply doesn't emit any noise in the air, why would you want to put it separate? You will gain absolutely nothing. I've tested the PSU from Minipulse - when using the synchro input there's virtually no noise, and when it's not synchronized the noise is terrible. My point is: use Minipulse PSU
My ugly *** board for GS4 just arrived

[daverave]

Dave the power supply doesn't emit any noise in the air, why would you want to put it separate? You will gain absolutely nothing. I've tested the PSU from Minipulse - when using the synchro input there's virtually no noise, and when it's not synchronized the noise is terrible. My point is: use Minipulse PSU
My ugly *** board for GS4 just arrived

Hi Eclipse....in some of Eric's designs i think the audio section was mounted in the rear box with the batteries so thought maybe it stops interference from tx section affecting the audio stability...thats great you got a gs 4 pcb..where can you buy them and what's the cost ????

[Orbit]

The biggest problem is that the profit is pretty small when switched on channel 2 .

[eclipse]

Orbit that's needed only if mineralisation is too high and you can't get it to work properly.
Normally you wouldn't want to use channel 2 (GB) cos it will result in less depth for sure.
It's better to have it and not need than to not have it and need it

The board is 2Layer + TH plating, silk screen,without solder mask cos it's too damn expensive (I will make it my self - I have UV paint),
150x100 - and it came to my door at the 4th day for 20$ total. It's a local company that doesn't work on the foreign market.
I just didn't want to make 2 layer board that needed to have TH plating, and don't have time to wait from China.

5 boards like these with good quality with DHL will come to 100$ for 10 days.. but this is just a proto board, I already found a mistake in my drawings