VLF MD (by Sascho - Varna)

[erolunall]

Hello

http://yakimov.homeftp.net/banditko/METAL%20DETECTORS/IB/

some schematics including Varna VLF

Best Wishes
Erol

[erolunall]

hello

http://www.savefile.com/files/1483952

disc test


from emekli amca Turkey


Erol

[tiktak]

Hi,

Leto,
Where are you?Havent post lately?
I have finished new coil for this detector but cant make it work!!!!
Now the wire is 0,25mm bare wire or 0,27 with varnish.Former size 18,5cm TX 50 25 25 and RX 100!But why this cant work?When I put back the old coil it work.But its slapy and with hugh d.
Sasho can you also give opinion here PLEASE,
And one more thing I cant measure TX or RX frequency with this new coil!??!
THANKS

[lonelyWOLF]

hello everybody
ı am a build this detector at ones. ı`m only work in two days and ok..after, fine-tunnig and test results on air, well..
best regards...

[tiktak]

Hi

Hi,
Sasho how are you?
I fowoled your advices and now I have better results,but I still wanna ask you a couple of questions.
You say that this coil is OO 19cm.This mean that the outer d of finished coil is 19cm?So,I have to use former with d=18,5cm and wind coils on this?Right?
And when winding RX coil first I wind 50 turns then 25 and 25?
And one more thing did I wind TX and RX in same direction or oposite?
Thanks

[Ultimate_Haze]

Zdr.

Zdr Ultimate_Haze!
Az su6to pravq tazi ma6ina.Samo 4e naposleduk nqmam mnogo
svobodno vreme.Na kra4e 1 na 5532 sledi6 nai malka stoinost
na promenlivoto naporejenie no su6to sledi6 i 4ustvitelnostta
ima edno polojenie pri koeto amplitudata e nai malka i detektora e nai 4ustvitelen(Ccomp e razka4en).Mislq 4e se pravi i nastroika na fazata ama tova e pri DD bobinite.Tuk Sasho da kaje da li se pravi.Bobinite trqbwa da sa ekranirani!Posle zaliva6
i s Ccomp. 100p(podbira6 go) pravih nulirane na bobinata.
Drugite dva kondnenzatora sa za nastroika na fazata na zemniq balans i diskriminaciqta.Tazi nastroika se pravi nakraq sled kato bobinata e zalqta.
Imai na predvid 4e kato opravi6 fazata na zemniq balans 4ustvitelnostta pada
i se pravqt nastoiki na praga i tn.Az do sega sum nanikude no skoro smqtam
da otdelq pove4e vreme za neq.Predpolagam 4e dvamata i sus sashovata pomo6t 6te se spravim.

Ami to i az sum na nikude za sega.Ama sum stra6no naduhan da probvam tazi ma6inka!
Ti ot kude si?I kak si tolkova zapoznat s tozi ured?

[tiktak]

Hi tiktak,
good news..
Discrimination will work only if coils are nulled properly!!
Whats the frequency of your Tx stage?
Also the Tx coil construction is critical in this design.
Try nulling directly from Rx coil terminals and look for smallest reading.

Hello,
Leto.
How are you?
Have you tested this PCB on real field?
I havent time lately but now I can measure my frequency!Please tell me from which points should I measure mt Tx stage frequency?
Thanks

gordıanus

golegi napravih tasi masinka mnoko hubavo ba4ka rx100 tx 50.25.25.030tel hubavo ba4ka dali imate razmeri za oşte po hubava antena golegi pomognete .saso pomogni 4akam pomos.blagodarya predvaritelno suray [email protected]

[Leto]

Hi,
Leto.
Yes same like on this nice pfoto!
I now that it will be hard without scope,but I think that there is aweys other way to achive the GOAL!
Thanks.
For C28 it should be 150n according Sasho!
What are your results?Have you make some progress?

C28 depends on Rx coil; try to find highest amplitude (ac voltage - measuring across Rx coil) changing C28 from 1n to 22n.

I will try!Buts lets make it clear I have to conect multimeter across RX coil and buy changing C28 from 1n to 22n to look for highest reading?But shell I disconect Rx from device in this moment?And then when I find the right cap.I have to search for lowest reading/null coil/?This 100pf c.comp is it conected?

Hi tiktak,
On your parts-placement drawing C27 is 150n and C28 is to fine adjust.
When adjusting/nulling coils keep everything connected!
Step 1: adjust overlap of Tx - Rx coils for lowest reading.. my multimeter (APPA107) reads then 2-10 mV(ac)
Step 2: try to find best capacitator for R28 to get the coils into tighter resonance - you will notice that sensitivity will increase with right capcitator value as will also induced voltage across Rx coil.
Due lack of time I did not test detector on ground yet

[tiktak]

Hi

Hi,
Leto.
Yes same like on this nice pfoto!
I now that it will be hard without scope,but I think that there is aweys other way to achive the GOAL!
Thanks.
For C28 it should be 150n according Sasho!
What are your results?Have you make some progress?

C28 depends on Rx coil; try to find highest amplitude (ac voltage - measuring across Rx coil) changing C28 from 1n to 22n.

I will try!Buts lets make it clear I have to conect multimeter across RX coil and buy changing C28 from 1n to 22n to look for highest reading?But shell I disconect Rx from device in this moment?And then when I find the right cap.I have to search for lowest reading/null coil/?This 100pf c.comp is it conected?

[Leto]

Hi,
Wellcome back Leto.
Where have you been?
Thanks for tip.I will try!I cant measure frequency because I dont have such tool!I will buy some multimeter with frequency tomorow!
What have you used for C28?!And one more question Where did you conect this extra 10n cap?On point 1 and 2 for TX?Did you put and across RX 10n cap too?
Thanks
p.s.this D2 on pictures is placed wrong?Right?Because I saw on your pictures that you have mounted oposite,not like on pictures?
Have you made good coil?What are your results?

Hi tiktak,
I'm available only on sundays these days..
You need pretty good multimeter to null coils with it.. frequency meter is also mandatory.
Extra 10n capacitator across points 1 and 2. (But this will depend on Tx frequency)
C28 depends on Rx coil; try to find highest amplitude (ac voltage - measuring across Rx coil) changing C28 from 1n to 22n.
Diodes as on photo in post# 49 - check shematic!

[tiktak]

Hi,

Hi,
Wellcome back Leto.
Where have you been?
Thanks for tip.I will try!I cant measure frequency because I dont have such tool!I will buy some multimeter with frequency tomorow!
What have you used for C28?!And one more question Where did you conect this extra 10n cap?On point 1 and 2 for TX?Did you put and across RX 10n cap too?
Thanks
p.s.this D2 on pictures is placed wrong?Right?Because I saw on your pictures that you have mounted oposite,not like on pictures?
Have you made good coil?What are your results?

[Leto]

Hi,
Leto.
Where have you been?Are you back here again?
I make this work,but still need help!
Its look like this is one hell of the detector!Very sensitive!
I still dont now for disc but the respond is fast and sharp!
I see that Sasho havent answer lately.

Hi tiktak,
good news..
Discrimination will work only if coils are nulled properly!!
Whats the frequency of your Tx stage?
Also the Tx coil construction is critical in this design.
Try nulling directly from Rx coil terminals and look for smallest reading.

had

t1 t2 2n2907 c12 47pf c28 150n tx coıl 10n antena 0.35 tel 50.25.25.rx100 w saso ispolzvah tezi elementi masinkata raboti stabilno no malko e slaba 10cm 1lv v vizduha da li da polvam t1 t2 bc 177 kıde imam greski mola pomogni cakam s netırpeniye da izleza na poleto moje li da mi dades razmerite na antenata blagodara predvaritelno

[tiktak]

Hi

Hi,
Sasho!
Why you dont answer?May be you haven't visit this forum soon?
I made yesterday a new coil!And the results are much,much better!I have used 1,1 mm wire because this is a test purpuses coil.I wound RX and when finished TX I had to add some turns with different wire,but I think that this wont boder me much.I made this on 18cm former to acive 19cm coil?
Then I start playing but I have noticed diferance at once!
Greate sensitivity!I dont mean depth,I meand feeling the objects!
I add for c12 18pf for C 28 10n and paralel to RX and on pin 1 and 2 for TX /looking from up to down/ I have add for each 10 n capacitators.
Havent nulled right,I am shore have atached multimeter in 200mV AC range to pin 1 on 5532 and have looked but get some strange readings?For what shell I whach?Lowest or highest reading?
And when I turn the disc knob I cant notise that it work!No change at all?
Why?
Anyway Again Great Work!
If you help me I will test it soon.Have a nice feeling about this detector.
Thanks