Classic III

[Leto]

IT WORKS

First I have to say thanx to all helping here..
CLIII is working now both in all metal and disc. modes
Fault was in bad LM324 - I replaced it with new one and it works.
I have also tried MAX448, MAX494, MCP604 all working no great differences.
Ivconic: Jackdetect already corrected 220K-47nf problem on his PCB, that 22k resistor is more tricky to spot.. also all jumpers are OK on protel file.
I made just some minor modifications like RFguard on upper side.

What I have learned from this?
*check ic's twice..
*Replacements for U3 (LF444) are:
LM324
LS404
TL084
MAX448
MAX494
MCP604
and probably lots of others

Now I have to make proper coil - probably one DD like Geo made and later on concentic.

[Geo]

Yes

Congratulation Leto . Now try to modify RP2 as at my schematic (one side at +E and the other at -E, not at gnd). You will get more sensitive .

[sisco]

NEW CLASSIC

http://md.operacija.com/forum/viewtopic.php?t=29

[Leto]

celebrating victory...

Geo:
I tried your modification and this is what I get:
No detection with RP2 form 0k to ~40k
Bad oscilations with RP2 from ~80k to 100k
In between there is a sweet spot with greatly improved sensitivity ,
around 50% (twice the range) better!!
But sensitivity control is now non-usable -> only for sweet-spot searching, also discrimination shifted .
I was thinking not to apply RP2 directly to -4.9V -> but to -2V or -1V using resistor devider.

sisco:
I have seen this modification but have not equipment to program PICs, also wrote email to constructor -> no-reply

Ivconic:
Nista novog - vise cene, iste plate

Me and Ivconic lived in same country about 15 years ago - but now if I want to visit him I must cross two or even three state borders.

[ivconic]

....


"...Nista novog - vise cene, iste plate..."

A kod nas je:

" Nista novog - mnogo vise cene, manje plate..."

Pozdrav!
Drago mi je da ti je proradio CL3. Sto se tice Geo-vog tip-a....i ja sam imao ista iskustva, ali mu nisam hteo reci da to ne radi dobro.....smatram ga prijateljem a nisam ga hteo razocarati...

Klasik je sasvim O.K. detektor ali probaj nabaviti Fisher-ovu sondu....bices zadovoljan...
Pozdrav!

[Geo]

Geo:
I tried your modification and this is what I get:
No detection with RP2 form 0k to ~40k
Bad oscilations with RP2 from ~80k to 100k
In between there is a sweet spot with greatly improved sensitivity ,
around 50% (twice the range) better!!
But sensitivity control is now non-usable -> only for sweet-spot searching, also discrimination shifted .
I was thinking not to apply RP2 directly to -4.9V -> but to -2V or -1V using resistor devider.

Yes, measure the resistance of rp2 when the detector works as you like and connect in series a resistor A to +E..a pot10K.. and a resistor B to -E, total resistance 100k.

[ivconic]

mod


There is a constant problem about coils for hand-mades. Either you have to make
your own(which is a problem), either you have to find proper one....
I was experimenting with various original coils so far....Some of those turns to be
almost good to work with Classic 3, but there is that "almost.." word.
I found out that mostly frequency is problem. Coil designed for 4kHz will not give
good performances with CL3, which working frequency is arround 6.5 kHz (6.35-6.9kHz).

I was asking myself how would it be if i can adjust frequency of CL3 to coil i
already have....for example some old Compass,Fisher,Cscope or any other original coil.
Theory aside, but i always want to check "in vivo" my ideas....so i made fast mod to
check this idea.
About this....it is not perfect,i know,but now i can very fast check CL3 behavior with
different coils....
So, i didnt expected any miracles, but miracle happened !!!!
I connected one scrap coil, which i have for years in my workshop (for testing purposes).
That coil already showed poor performances with original CL3 setup...
But now, with frequency adjusted pretty off original CL3 frequency, that coil showed
"wow" performances, detecting 2cm coin at 50cm's (even more) in the air...!!!!
It is too early to make any conclusions.....This setup has to be tested in real
conditions (in which i doubt is gonna keep same performances)....but i have a hunch
that some positive "drifts" in performances could be gained, this way....
I will see...
Therefore here it is, so if anybody interested, may experiment even further.....
Much better experimenting setup will be some functions generator connected in Classic 3
setup, instead original oscillator. I have XR2206 on my mind, and do plan to draw pcb of
CL3 with it included....but it will take some time, right now i am to busy...maybe in next
months....
One more thing; this setup looks nice! Discrimination remained as it was with original
oscilator, pinpointing too, stabillity is pretty good...??? I didnt expected that good
performances..!?
Any ideas?

[ivconic]

More...


More stuff....
I wouldnt like if somebody think that i am "joker" here....(like some people).
So here are some pics of my works on this subject.
I soldered out original oscillator from CL3 pcb, (all components included)...
Already made smaller pcb and put on main pcb in "piggy-back" manner, connected with
hard wires to proper points...
During testing i used Spectrum analyzer(on my lap-top) to check overtones.
So, miracle again!!!? TLC555 showed very clear output with "tame" overtones, unlike
original oscillator which were rich with strong overtones!?
Relation between main signal and overtones is much better than expected.....maybe
this was main problem at the begining?
I think that CL3 is perfect "console" to experiment further....
Any tips?

[Darko]

[quote=ivconic;51231]


Hi Ivconic. I don’t know so much about MD electronics but making coil for me is a nightmare. I have some Cscope coil and if there is a chance to use it with cl3 this will be wonderful. Please can you post layout of this addon PCB?

[Geo]

Hi ivconiv .
Do you remember the details of your coil (it looks a DD coil)???
Check it because you may have reflected signals from ground...
Other way it is time to try it .
Regards

[ivconic]

....

Sorry Geo, i made this 5-6 years ago and put in scrap in my workshop....Using it just when testing some devices.....I remember only that omitted faraday cage (i forgot it than), at the time, so i scraped it....Yes it is DD coil i made for some old Cscope once...
Never mind coil...any coil....it was just experiment to check some signal preferences, to get more clear picture about things...I do not intend to use this coil ever.....I wanted just to check if TLC555 can do the job or not.

About pcb for addon....it is hand draw, it will take me to scan it....No need for that since it is as simple as it could be. No job at all to draw your own...

I want to return and remind on idea....How about XR2206 oscillator for Classic 3, with all adjustments available? Ha Geo? What do you think?
In that case we can adjust amplitude,shape,phase...with trimmers arround XR... I think it is very interesting....What do you think?

[Geo]

Hi Ivconic .
If you can detect a small coin at 50 cm what other are you looking for ???
You have the perfect coil with the perfect detector !!!!!
Now about XR2206...yes itis a very good IC..I have tried it as sine generator before 23...25 years ???? It is a good way to regulate the power of the detector transnitter. I have one piece so if i will have free time to give it a try
I read again the message to test it and OOHHH my GOD !!!!!!! Before 23...25 years .....I think that it is yesterday ....yes i was a child
Regards

[ivconic]

....

"...(in which i doubt is gonna keep same performances)...."

Yo, Geo! Take it easy! It was on the fly, with pretty crazy adjustments...
Lack of instablillity even in the air...what i can expect on the ground...or highly mineralized ground???
I just wanted to check TLC555....
When adjusted properly to work stabile on the ground i really doubt that it can detect same coin on more than 30-32cm....even that is hell of result!
But i just have to wait few days and see...
regards!

[Geo]

"...(in which i doubt is gonna keep same performances)...."

About performances he..he
Your Classic III have best performance, but me ...i don't think ....what are you say ... we have about the same age

Now if you will detect a 2cm coin at 30 cm in the ground then it is the best detector all over the world.
My Regards

[ivconic]

...


Agree!

I am 40...

regards!