from Zero to Hero - detector-electronic workshop

[Funfinder]

Hi people interested in building own detectors and creating developments or own modifications and improvements,


we need for this forum a thread as reference and as learning-course which documents the electronic metal-detection possibilities
from the early beginning up to the newest hitec circuits.

We have enough profis here that can lead anyone into the right directions, from BFO (beat frequency oscillation), TR (transistor), IB (induction balance),
MAG (magnetometer) and PI (pulse-induction) up to new developments and inventions we wanna achieve.

After about 5-10 pages we should be already real into complex electronical details but it should be not too fast,
so that many persons with some electronical knowlegde or interests can understand how this stuff is working.


I will start with the basics of inductivity, amplification and signal output.


First some hints:
The absolute most simple metal detector is a crystal radio with short antenna.
A metal object nearby "consumes" the AM-energy and distorts its frequency.
it contains: coil, diode and sensitive audio-output.

The next very basic one is the trafo-detector (transformation).
AC energy A gets transformed by trafo coil A over coil B to AC energy B but if there is a metal nearby the result is different.
(principally this is already IB or in other words - ID - induction difference)

extremly simple also is the Volt-Meter detector - moving some piece of iron next to a coil will move the milli- or micro-Volt-Meter
because of the electromagnetical force and interference.

also very basic works the electrical potential detection with high voltage - the flash will hit the metal-roof and not the
plastic party-tent in the garden. This is not only distance but also that in metal the electrons can flow very good so the potential
can get much closer and more powerful to the static charged area.


All those principles so far have get none or very few attention.
Instead the TX-RX reception differences get electronically analyzed and formed to an output signal by sound, light or some kind of display device.

So we must start with some simple LC-oscillators - also called "tank", circuits who keep them on a certain level, followed by output stages.

Here is the begining, if you need any explanation - just ask.

The next step will be the "real" start of metal-detector schematics - I hope some profis here also can provide them and explain how they work.


but lets start with some very basic circuits:

01 LC tank circuit.jpg
02 colpitt oscillator.jpg
03 AC trafo.jpg
04 AC interference.jpg
05 EM field.jpg
06 transistor as AMP.jpg
07 induction amp.jpg

[Qiaozhi]

Hi people interested in building own detectors and creating developments or own modifications and improvements,


we need for this forum a thread as reference and as learning-course which documents the electronic metal-detection possibilities
from the early beginning up to the newest hitec circuits.

Are you trying to create an alternative to "Inside the METAL DETECTOR"?
Inside the METAL DETECTOR - Published September 2012

[Funfinder]

I almost thought that such a message would come.

Great product placement, like the info on top of the forum, and my full respect for this book, because if a person is interested in metal-detector-technology -
and I must admit that I was already interested in electronics and metal-detection when I was 10 years old, then of course it is typical that this person also
likes persons with same interests.


To be honestly, when I wrote this new thread I really have not slighty thought about such a topic could be some kind of "concurrence" to this book.
And maybe not everything is described in the book so we can talk about it here or try to create special new developments and find new ideas.


Just forget it, because if now, after some days still no single person was interested to contribute to this thread, they better buy your and Carls book or
some other books in that direction, or they can read some electronic-crash-courses or google for explanations - I don't care. This was just an offer and
if there is no interest the people here don't deserve it, anyway. As long as they know what is the correct side to hold the soldering-iron I hope they still
will be able to create some DIY-detectors, enjoy it here and understand a little bit how this stuff is working. But of course I will not explain it again and again.


If this forum needs no "introduction" in metal-detector-electronics its not my personal problem. It would have been more complete, like a technical product is
more complete if it comes with a good user-manual, but its not essential important.



Perhaps I should start another thread with the question:

What nowadays really still is fascinating enough in metal-detection-technology???

Because rebuilding and modifying a little bit over and over again some 20 year old circuits for shure is not exciting!

It may be fun for teenagers at the physic-class-room but not for perfectionists or inventors who wanna reach for the stars or ultra wide depths....

[golfnut]

We all know physics hasnt changed recently but some of the boutique detector models are making progress.

The only way to progress hobby machines on here from the early 90s is to learn a a bit of dsp. So we can have decent tight filters etc

Its relatively easy to do a four tone machine for target ID etc


Auto geb is probably done more successfully in SW than having choppers and lord knows what else.

A clear reliable VDI like on a T2 is as we all know another SW task


We are 15 years behind as hobbyists.

S