VLF MD (by Sascho - Varna)

[salih]

Hi Salih
Sascho VLF detector is not easy project , you need for calibration to oscilloscope.
Best regards.

can you tell me , What I did wrong On the attached picture. If you answer to this question you are realy help me.
By the way Results 2.2 coin in Air 22cm, Rejection Hot rock and Iron.
When I'm rmove C28, coin 2.2mm in air 30cm Rejection Iron and read hot rock.
Best regards

[salih]

No one can help

[Max]

No one can help

Hi,
as I said before I did not made this MD, just experiments with oscillator and coils, it's all about that, be patient and try to tune coils properly

resonant designs are all about that: if properly tuned you have great sens and good disc and geb BUT a little mistake and you'll get lot of troubles and no good operations

btw you need oscilloscope to properly tune phase shift, though this is not mandatory for nulling (can use other strategies for just nulling)

my advice is to review VERY carefully your PCB for mistakes (the pcb is small, few stuff, requires just few time), then wirings and last if all OK concentrate on coils, there's at 99% the problem and if you fix that almost sure you'll got extra depth and good disc and geb

belive me, Sascho design seems very nice just looking at schematic, the only problem in replicate it is at coil tuning; not to say once you have properly tuned MUST fix everything very hard with epoxy, otherwise wil untune easy at first movements: coils must be rigid as iron in these VLFs, absolutely mandatory, and do not forget proper shield otherwise once you go on real soil you'll get erratic from charge coupling of coils with plane of soil

regards,
Max

[salih]

Hi,
as I said before I did not made this MD, just experiments with oscillator and coils, it's all about that, be patient and try to tune coils properly

resonant designs are all about that: if properly tuned you have great sens and good disc and geb BUT a little mistake and you'll get lot of troubles and no good operations

btw you need oscilloscope to properly tune phase shift, though this is not mandatory for nulling (can use other strategies for just nulling)

my advice is to review VERY carefully your PCB for mistakes (the pcb is small, few stuff, requires just few time), then wirings and last if all OK concentrate on coils, there's at 99% the problem and if you fix that almost sure you'll got extra depth and good disc and geb

belive me, Sascho design seems very nice just looking at schematic, the only problem in replicate it is at coil tuning; not to say once you have properly tuned MUST fix everything very hard with epoxy, otherwise wil untune easy at first movements: coils must be rigid as iron in these VLFs, absolutely mandatory, and do not forget proper shield otherwise once you go on real soil you'll get erratic from charge coupling of coils with plane of soil

regards,
Max

Thank Max very much
All you said is true
Now I get in the air 35 cm and 27 cm in the soil (((Diameter coin 2.2cm)))
and i think this Detector very good from Tgsl
Thank Max very much for tip

[salih]

Problem

hello 2 all
I tested sascho vlf Detector in Sand and I have good GB But I have a problem with some rocks and bricks.
if any 1 can help I Am wait help how i can get good GB what i do

[sinko1]

hello 2 all
I tested sascho vlf Detector in Sand and I have good GB But I have a problem with some rocks and bricks.
if any 1 can help I Am wait help how i can get good GB what i do

Hi salih,please upload you video with sasho vlf.Thanks

[Pompey]

This kind of detectors can`t reject hot rocks and bricks.You will have to adjust ground balance pot at each soil type.Therefore if you adjust GEB to reject bricks ,it will reject only bricks,for hot rocks is the same.This type of metaldetectors are very deep for normal soils,and useless for active ground,hotrocks... If you want to reject bricks,hotrocks and active ground in the same time you`ll have to made another type of detector - Sasho`s S1 for instance.

[syed ayub basha]

Hai, tell me what depths this detector will work. can we use large size coils?

[Pompey]

If you mean the detector,made by Salih ,you can use large coils 21/21cm OO for instance.With such a coil it should detect 1euro at 50cm.But it will be hard to make a big coil with high quality-the coil must be absolutely stable.If you mean S1 ,it detects 1 euro at about 30cm with DD27.

[salih]

Experience

hello 2 all
For any one wants to build VLF MD (by Sascho - Varna)
Do not use in T1 T2 2n2907 is bad Option .
I dont have big Experience in Electronic but I tried BC177 its so good my md became more Sensitivity
Greetings

[6666]

BC177 - BC177 PNP Small Signal Transistor


Features

• Collector-Emitter Volt (Vceo): 45V
• Collector-Base Volt (Vcbo): 50V
• Collector Current (Ic): 0.2A
• hfe: 125-500 @ 2mA
• Power Dissipation (Ptot): 300mW
• Current-Gain-Bandwidth (ftotal): 100MHz
• Type: PNP

2n2907

• BIPOLAR TRANSISTOR, PNP, -60V TO-18
• Transistor Polarity: PNP
• Collector Emitter Voltage V(br)ceo: -60V
• Transition Frequency Typ ft: 200MHz
• Power Dissipation Pd: 400mW
• DC Collector Current: 600mA
• DC Current Gain hFE: 100
• No. of Pins: 3

[salih]

my video

http://youtu.be/Gay6ooa1GzA

[xycy]

Здравей Наско,
Искам да направя една Грозданка: 2х160н. на ТX и RX. Можеш ли да ми кажеш коя схема е по-добра: на Сашо с 2хCD4007 или на тая Грозданка.
Благодаря

[Qiaozhi]

Здравей Наско,
Искам да направя една Грозданка: 2х160н. на ТX и RX. Можеш ли да ми кажеш коя схема е по-добра: на Сашо с 2хCD4007 или на тая Грозданка.
Благодаря

Please read the Basic Rules of the Forum and make your posts in English ->
http://www.geotech1.com/forums/showt...-of-the-Forums

[maikl]

Здравей Наско,
Искам да направя една Грозданка: 2х160н. на ТX и RX. Можеш ли да ми кажеш коя схема е по-добра: на Сашо с 2хCD4007 или на тая Грозданка.
Благодаря

Здравей xycy.
Поставете схема Грозданка, за да се види и ще получите отговор.
Е същото, тъй като това?
Hi xycy.
Set Grozdanka scheme to be seen, and you'll get a response.
Is the same as this?