Let's made a PC-base metal detector with usb interface !!!

[Aziz]

Hi Aziz,

I finally found some more time to play with your simulations today. Looks really interesting

Concerning class-E, there is a method to calculate the caps in one of the CPT links I posted a few days ago. This works well as long as the load impedance is very accurate and the switch resistance is almost zero. After I replaced the MOSFET with a 2 mOhm type, the calculation results were within 100nF of the values needed for the simulation to work. You have probably noticed that the circuit is very sensitive to small variations of the cap values, and even worse, also to variations of the load impedance. Just a few tens of mOhms more or less and it completely stops working. So probably not useful for us.

Your TEM 2.0 is far less sensitive to variations of cap values and coil resistance. I got the same simulation results as you posted in the Wideband thread:
http://www.geotech1.com/forums/showthread.php?20163-WIDEBAND-%28BROADBAND%29-TECHNOLOGY&p=167464#post167464

Very impressive Thanks for sharing this - I will definitely take a closer look within the next days.

Thomas

Yep, the class-E TEM is critical. Leave the optional capacitor as it requires the ZVS-rule (shorting the optional capacitor via the mosfet - no good, when the capacitor has stored energy).
The TEM 2.0 is way way easy and not critical.

Your are welcome. Happy using and sharing.

Cheers,
Aziz

[Aziz]

Magic Multi-frequency OSC Variation

Hi all,

I want to show you what happens, if you connect a second resonant capacitor (CTx2) to Tp2 (or Tp1) and V- connection. See the coil current wave form below. Do you see a basic similarity to the TEM 2.0/Class-E TEM coil current? Ok, it hasn't enough radiant sine waves but a 0.5 sine radiant at low frequency and 0.5 sine radiant wave at high frequency.

If you look at the FFT spectrum of the received signal (Rx), you get a nice multi-frequency response (not equialized however). You can do a two or three frequency demodulation with ease. And this is really enough to make a really good ground balance.



Add this capacitor and you have a multi-frequency oscillator (a mini TEM2.0 *LOL*). The power consumption rises however. That was the magic missing link.

Cheers,
Aziz

[Aziz]

Minor Changes to the Latest VLF OSC Detector Controller.

Hi all,

I have built the latest VLF OSC Detector Controller (I am referring to the schematics in post #1627).
(Link: http://www.geotech1.com/forums/showt...202#post165202 )
It works fine with NE5532. When I am using the lower noise NJM2068, the TX reference voltage attenuator circuit is oscillating at higher frequencies (due to switching transitions of the fets and fast NJM2068 ). To tame this behaviour, add a capacitor to the feedback of the TX reference voltage attenuator (capacitor parallel to R11). Start with 47 pF and increase it, until the high oscillation gets damped (low-pass filtered). But no more than 220pF (enough).

I even have reduced the resistors value R11, R13 from 10k to 4.7k to use the magic modification (multi-frequency option) so the TX reference voltage gets attenuated more.

BTW, the magic option works very fine.

Cheers,
Aziz

[jheissjr]

I have built the latest VLF OSC Detector Controller (I am referring to the schematics in post #1627).

Aziz, Do you have any pictures?

Jeff

[Aziz]

Aziz, Do you have any pictures?

Jeff

Hi Jeff,

unfortunately, I have screwed my good old digital camera some time ago .
Fortunately, I had the cam of my girlfriend handy to make a picture of the latest VLF OSC Detector Controller board this morning (the 3rd prototype).
But haven't put it into a case yet.



Cheers,
Aziz

[jheissjr]

Looks nice! What are you planning next?

Jeff

[Aziz]

Looks nice! What are you planning next?

Jeff

Inventing to prevent others inventing.

(Just kidding)

Software coding. Releasing the beast. Causing the "total metal detector thermo nuclear meltdown".

(Just kidding)

I have some interesting ideas in my pipeline. As soon as there is more time, I'll be working on them.
Cheers,
Aziz

[cossak33]

http://www.md4u.ru/viewtopic.php?f=11&t=3772&start=175

[Aziz]

http://www.md4u.ru/viewtopic.php?f=11&t=3772&start=175

Hey cossak33, thanks!

I have found an interesting application there:
http://www.fmf.uni-lj.si/~ponikvar/P...asurements.pdf

Well, I can measure the phase angle much more accurate: +/- 0.001 degree.

Anyway, interesting paper.
Cheers,
Aziz

[cossak33]

Hey cossak33, thanks!

I have found an interesting application there:
http://www.fmf.uni-lj.si/~ponikvar/P...asurements.pdf

Well, I can measure the phase angle much more accurate: +/- 0.001 degree.

Anyway, interesting paper.
Cheers,
Aziz

всем привет там уже выложили Vi правда работоспособность я не проверял пока нет времени

[Qiaozhi]

всем привет там уже выложили Vi правда работоспособность я не проверял пока нет времени

Please read the forum rules -> Basic Rules of the Forums
and make your posts in English.

[cossak33]

Please read the forum rules -> Basic Rules of the Forums
and make your posts in English.

Hello there already posted Vi true performance I did not check there is no time

[Aziz]

Another Sound Card Application

3D-printer: The Peachy Printer
http://www.youtube.com/watch?v=80HsW...layer_embedded

There are more majik guys out there.


Aziz

PS: more vid
http://www.youtube.com/watch?v=aCbNua94Zfc

[Qiaozhi]

3D-printer: The Peachy Printer
http://www.youtube.com/watch?v=80HsW...layer_embedded

There are more majik guys out there.


Aziz

PS: more vid
http://www.youtube.com/watch?v=aCbNua94Zfc

Apparently there's 27 days to go ... and then you can buy one!
http://www.dvice.com/2013-9-23/3d-pr...peachy-printer

[joop]

To bad delivery is about one year from now. Nice project though!