How this circuit like?

[Qiaozhi]

Maikl, note that KT315 and I know Russian.
Search WEB for his both names "Анатолий Кутовой" and for my both names "Михаил Волков" to see how many people in Russia have such names.
In Serbia, Russia and Bulgaria used the same alphabet and our languages are so close that if everyone spoke in his native language, we'll get along without an interpreter. We will always feel not only as cousins but as brothers in Christian religion. Despite I'm not religious at all and not go to church, I cling to one important value of the Christian religion that says: LOVE THY NEIGHBOR!
So I feel hatred towards people that although Europeans and Christians, violate that God's commandment. Nazis and fascists are most violated that God's commandment during WWII. Most of these criminals must have been religious, and must have gone to church before and after making a crime to humanity.
European values are required to treat with love and respect for all, regardless of which country they were born, regardless of what knowledge they have, regardless of which party they are forced to join.

Although I agree with your post, please can we terminate this discussion and return to the main topic of this thread. Remember that you are in the Schematics Forum.

Political and religious discussions have a bad habit of rapidly becoming heated, and Geotech is not the place for this.

Thanks for your understanding.

[mikebg]

Maikl, note that KT315 and I know Russian.
Search WEB for his both names "Анатолий Кутовой" and for my both names "Михаил Волков" to see how many people in Russia have such names.
In Serbia, Russia and Bulgaria used the same alphabet and our languages are so close that if everyone spoke in his native language, we'll get along without an interpreter. We will always feel not only as cousins but as brothers in Christian religion. Despite I'm not religious at all and not go to church, I cling to one important value of the Christian religion that says: LOVE THY NEIGHBOR!
So I feel hatred towards people that although Europeans and Christians, violate that God's commandment. Nazis and fascists are most violated that God's commandment during WWII. Most of these criminals must have been religious, and must have gone to church before and after making a crime to humanity.
European values are required to treat with love and respect for all, regardless of which country they were born, regardless of what knowledge they have, regardless of which party they are forced to join.

[maikl]

kt315 like your avatar "general Ratko Mladic" you're my brother, a Serb. Lithuanians were never fascists and aggressors. Unlike some other people who were always on the side of the fascists and the occupier (in the first and second world war...). mikebg wrong one hundred kidding kt315. kt315 contributed greatly to Geotech (sometimes in their own strange way). kt315 give the direct answers and schematic not entangled graphs and philosophical answers unlike some. Best regards and to get serious not to be children.

[mikebg]

your General and his unterfeldwebel Alex are ready to trip in Bulgaria at SUNNY BEACHES! tu-tuuuu!!

Анатолий, если говорить серьезно, в Болгарии, в сентябре погода, как правило, хорошая, теплая и устойчивая, а цены на гостиницы значительно сокращены. Прогноз является то, что погода будет хорошей до понедельника. Более отдаленные прогнозы метеорологов не дают. Мы вернулись с моря потому что с вчера дети на школе.

[kt315]

your General and his unterfeldwebel Alex are ready to trip in Bulgaria at SUNNY BEACHES! tu-tuuuu!!

[mikebg]

Sieg Heil, Herr General!

[kt315]

[mikebg]

Below attached is the page with translation in English.

[mikebg]

fascists, you mean hazi here probably, gave people the work places, got up the economic, developed the industry. now I have not the work! I have been retired without my wish! so think what you write about.

Dear KT315,
Accept my apologies, that I judged you as fascist and Nazi, but I was misled by a website that everyone can see:

http://www.reibert.info/forum/showthread.php?t=83723

The information for you is in Russian:
Место жительства: Литва
Интересы: антропология. социальная инженерия и философия. поиск рационального зерна, во всем.
Профессия: технарь
Дата рождения: 8 Янв. 1962
Регистрация: 10.04.2005
Всего сообщений: 593

Translated in English:
Location: Lithuania
Interests: anthropology. social engineering and philosophy. Search of truth in all.
Occupation: geek
Date of birth: 8 January 1962
Registration: 10.04.2005
Total Posts: 593

I do not read everything carefully, although I know well Russian. In reality the site offered for sale items from World War II. In that forum you are only a seller of such targets.

The reason for my confusion was that each participant in the forum had any fascist military rank, that's why I composed the following portrait for you:

[mikebg]

Homefire, please read my posting #7 to understand why the circuits in your links are primitive. Posting #7 contains information for design of modern BFO type metal detectors, but it is only a part of design principle. The problem is how to design amplifier used in search oscillator.

The following description of improved principle for search oscillator is not to **** KT315 and Maikl that BFO metal detector has future, but is just continuation of analysis started with posting # 13. Those who believe that the principle of metal detecting with search oscillator (BFO) has no future, should be interested what principle has a future. Let we analyse the best operating principle for a future MD without search oscillator. I described three main things of this principle in posting #13.

Let continue with question "How to classify a BFO metal detector in frequency domain if there are only two types? Whether BFO is narrow band or wide band?"

The TX coil of search oscillator creates magnetic field with "noise induction". In oscope (in time domain), noise induction seems different from sine induction and pulse induction, but how seems frequency spectrum of noise? As you know the noises are different in "color". Wide band means "white" noise.

We can design a metal detector using white noise generator to drive TX end stage. The TX will operate without oscillation. The BFO MD is specific case of this design because instead noise generator we use an amplifier having very high gain. The gain can not be achieved using in amplifier only one transistor. Our amplifier should amplify internal thermal noise until output starts to saturate.

Let we use in search oscillator an amplifier with adjustable bandwidth and gain. Imagine a MODE switch having two positions: NARROW BAND and WIDE BAND. How seems output of such amplifier at different modes when feedback is disconnected. It can not oscillate.

The left figure of attached image shows output when MODE switch is in position WIDE BAND. The gain is increased until output starts to saturate. The noise seems as a band thick no more than 1/8 to 1/6 of distance between saturation thresholds.

The right figure shows output signal at NARROW BAND position. We should increase the gain to obtain operation near to saturation. This is most important effect of narrow band operation because increased gain means increased sensitivity. The visual effect is as if there is a chaotic modulated oscillation, but in reality is amplified noise at a narrow band.

After we designed a search oscillator operating as narrow band or as wide band metal detector, remains to write in the operator's manual when BFO MD should operate with MODE switch in position NARROW BAND and when in position WIDE BAND. Since this question is as quiz relating not only to BFO but to all kinds metal detectors, I will put discussion also in section "General Electronics". The title of this thread will be something like "Block diagram of RX for ultimate metal detectors" or something more short.

[homefire]

Someone over in china must be smart as hell!

They have the Jobs and we here in the USA don't have squat!

My first detector was a BFO, and had to adjust it every 20 seconds or so.

I found a silver quarter with it at 8" 20 minutes after taking it out of the box.

That one was based on LC tank circuits ran at 360KHz.

Using Quasi Digital circuits and Crystal controlled Ref Osc you have another Ball game.

Too Simple but cool.

http://www.extremecircuits.net/2010/...ocator_13.html

http://www.hobby-hour.com/electronic..._detectors.php

[maikl]

mikebg I also agree with the kt315 : "BFO has no future" (regardless of the frequency). Can improve sensitivity and a bit of stability for small objects on the surface. In my opinion, these projects have a futurethe as shown (the demands of the average hunter). I am interested in your opinion. Not because it comes to your countryman, but seems really interesting in every respect.

[kt315]

Mike, you waste your time on BFOs. maybe this guy tomorrow will reached Tinkerer level and WILL GIVE YOU absoliutely fresh info from Chinese hight tech electronincs... I very hope it will be... IMO you do NOT up his level - you are only getting DOWN your level to his one. this guy is similar to - Chinese adage, by the way - "to try find out Black Kitty in the dark room" - and you absoliutely despairingly try to help to find this black cat.
I have gave all info on Chinese metal detector MD-5008 as much as I only can able. from PCB layout, tracing, the schematic, the coil inside etc. this detector is best for all metal types. has full static mode. CHINESE detector.
I am not Confucious... but believe me now - there are much knowledgeable people in the China...

sincerely Yours

[mikebg]

Maikl, let KT315 and Admin try to understand the problem since I and you can not express in good English.

As you know, I'm only a hobbist designer, but I know how should operate the future most sensitive metal detector because I'm familiar with design process. My hobby is to design transceivers for QRP amateur radio. The design process starts with analysis of ideal operating principle in frequency domain and composition of best operating block diagram. I know three main things for block diagram:

- The gain of RFA in front end of RX should be limited by noise, not by EMI AIR and GND signals.

- The real GND signal should be used for referece voltage at synchronous demodulation.

- After demodulator we need a band pass filter for damned low frequencies (below 1Hz).

The block diagram can not be designed with experiments and SPICE. Only knowledge and thinking in frequency domain can help to improve sensitivity of metal detectors. I can not see discussion on block diagram in the metal detecting forums.

Note that your above posting is a step in this process. You start to analyse different operating principles and to show their drawbacks. However your step and its direction are made in darkness because you are not thinking in frequency domain.

In frequency domain exist only two types metal detectors: narrow band and wide band. Attached figure illustrates TX current at both cases. For symbolic explanation I use sinc pulse as nonsine induction, because it generates flat frequecy spectrum in operating band.

I know that you wont agree with me, but wide band metal detectors (as conventional PI) are more "discriminative" (a bad term) because deliver more information for spectral characteristic of target. However the term "wide band" means for a designer minimal stray capacitances and increased energy dissipation because he need damping resistors to discharge stray capacitances.

Narrow band metal detectors are energy efficient because they use tuned circuit in TX. Stray capacitances are not important. A single frequency metal detector delivers information for only a point of target's spectral characteristic. That means it is less informative (discriminative) because TX operates with sine induction.

CONCLUSION: A properly designed PI metal detector should discriminate much better than a VLF MD. Since I hate the bad terminology used in this conclusion, I will expain it with other words:

If we need more information for targets, the TX coil should excite environment with nonsinusoidal current.
The radiated magnetic field should contain frequency band in which spectral characteristics of targets are different. In ideal case the TX current is as sinc function.

However since metal detectors are only narrow band and wide band types, how to classify a metal detector with search oscillator (BFO or frequency shift MD)? I know how search oscillator excites targets.

[maikl]

After long time in production with flat legs (as shown below), transistor KT315 is now produced in case TO92:
http://www.transistor.by/i/pdf/kt315.pdf

In the past century, 2N3904 was the most widely used cheap transistor for general purpose in the United States.
The same can be said of the transistor KT315, widely used in the ex country Sovjet Union or USSR. Lithuania, Belarus and Russia participated in this "union" (Bulgaria was a secret participant :-). Now there is no the country Sovjet Union, but in Belarus remains production of KT315.

What means nickname "KT315"? Is it nostalgia that feels Anatolij Kutovoj for communism (when there was no unemployment in the Lithuania) or nostalgia for nonexisting powerful Soviet Army (where Anatolij had to fulfill his military service about 30 years ago)л

Not! The alias KT is simply a school nickname comming from Kutovoj.
Dear KT315, the letter "T" is not from of yours first name because it is in the middle of "AnaTolij". Ask your ex classmates to tell you that KT comes from your last name, but this is absolutely not important. Important is what participants in this world forum feel for a gentlemen known here as KT315.

I have feeling that Anatolij is an excellent expert in this hobby, sharing his knowledge almost with all.

But why "almost"?

Because there are several participants who do not feel the same as me.
If I was drunk and I had written (in such a condition) something similar to posting #2, once sober I'd be ashamed. I'd apologize to Yhl and ask the Administrator to delete that posting.

As Anatolij not guilty, that was born in the communist country Sovjet Union, upposed to serve in the Red Army, and Yhl not guilty, that is born Chinese.

However, everyone (even drunk) is to blame for his behavior to others.

Does not have to ask the administrator to delete the message. Whoever wrote the message can I change it whenever wishes (for example, can delete all and put "?"). Let us return to the topic mikebg.Tell our friend yhl that the classical BFO will not reach that far(It is obsolescent type detector).Since he is searching for ordinary iron and there was not substantial discrimination against those he recommended a PI detector.Me PI detectors are not particularly interested in (because of poor discrimination, and high power consumption).You are better experts than me and he therefore recommended a PI detector that is easy to manufacture and handling.