GOLDSCAN 5 SCHEMATIC QUESTION

[dbanner]

As far as the pulse width is 100 us. What is the inductance and resistance of the coil. Thanks

Inductance of coil around 620uH.(25 turns, 0.4mm wire, 30cm Diameter)
Look here you will find 1M resistor in schematic http://www.geotech1.com/forums/showt...scan+schematic

[dbanner]

I think I have found the problem you are experiencing. Where is the SOURCE of your MOSFET connected? There is a 2ohm/1W resistor from source leg of MOSFET in series with the supply. Do you have this?
This is omitted from PCB layout as it was intended to be part of power supply board which I can't recall if I posted the layout for it.
I think layout is good, maybe you can put some pics of your board.

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[ATTACH]44817[/ATTACH]
[ATTACH]44818[/ATTACH]

Hello there, well I see you have made PCB using a layout that was designed by me.
This layout has never been tested and proven, so it is unverified.
It was meant as an experimental platform only for verification purposes of circuit.
That being said, I cannot say for sure that it is 100℅ accurate. I think there was a small error on area of tx stage which I later corrected, but can't recall if I posted the corrections.
I will have a look at my files.
In the meantime, have a look at the tracks surrounding the MOSFET and it's accompanying circuitry, comparing to the schematic.
Please post the schematic you are using.

[ispanyol2]

As far as the pulse width is 100 us. What is the inductance and resistance of the coil. Thanks

[dbanner]

The gs5 schematics are good if you know what you are doing. The pulse width is very important to keep in check, otherwise you see the magic smoke. I posted an accurate schematic on this thread and others also. Use a good translator and read through the thread. All answers can be found with good student homework.

[profesor]

3600uH coil error 300uH

[ispanyol2]

Sory.


no same pcb. I read somewhere. I think the pictures on the forum are pcb gs5a. Turkish schemas published here again should be Gs5b because it is seen that there are 3 jfet in the scheme. As shown in the diagram, the transistor is incorrect if the resistance (470) at the transistor end that drives the Irf740 is correct. That way, he can't drive the Irf740. According to the information published on this subject Tx solid faulty 470R resistance that I have previously stated is burning. this scheme is either nobody has done or is not aware of the problem. What is the original mono coil values of Gs5. No one shared it, or a secret. thanks

[Qiaozhi]

Aynı pcb yok. Bir yerlerde okudum. Forumdaki resimlerin pcb gs5a olduğunu düşünüyorum. Burada tekrar yayınlanan Türk şemaları Gs5b olmalıdır, çünkü şemada 3 jfet olduğu görülmüştür. Şemada gösterildiği gibi, Irf740'ı çalıştıran transistörün ucundaki direnç (470) doğruysa, transistör yanlıştır. Bu şekilde, Irf740'ı süremez. Bu konuda yayınlanan bilgilere göre Tx katı arızalı 470R daha önce belirttiğim direncin yandığını gösteriyor. bu şema ya hiç kimse yapmadı ya da sorunun farkında değil. Gs5'in orijinal mono bobin değerleri nedir? Kimse paylaşmadı ya da bir sır. Teşekkürler

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

[Orbit]

profesör you are right Something does not fit on these semantics only if you do it in your own way I've solved differently in the processor.
All of this works or not in the correct way !

[eclipse]

There is no heat problems. 3 watt resistor does get hot but its acceptable.
Also use 3 watt resistor for the 1k preamp input resistor.
Look for errors in your design. Is the mosfet switching at 3khz and tx width is 100us.
If these values are off you might get problems you describe.

[profesor]

The goldscan 5 detector has a frequency of 3.2Khz TX pulse duration of 100uS. According to the output voltage is 14.4V, the IRF passes a fairly high current from the 740 mosfet line. It is about 2.5-3ohm along with a fast coil of 3600uH, and the internal resistance and serial source resistance of 0.065ohm. The current is 600-700mA.
Now let's do some calculation:
14.4V / 3ohm = 4.8
4.8A / 1sn = 4.8A / 1000000 = 0.0000048A Current at 1uS Current at x100uS tx = 0.00048A Impact power at 1uS = 14.4Vx0.00048 = 0.006912W The power at 1sn = 0.006912x3200Hz = 22.1114W is spent.
The voltage and current on the damping resistance are exponentially
Let's make an account below.
Let's accept flayback vodka average 600V.470ohm 2w
damping resistance.600V / 470ohm = 1.27A


1.27Ax3200Hz = 4067A Of course, this is not a real figure.
but in practice, the damping resistance can be very hot.


Now here's my respectable Eric foster how did you fix this heat problem.?

[ispanyol2]

Aynı pcb yok. Bir yerlerde okudum. Forumdaki resimlerin pcb gs5a olduğunu düşünüyorum. Burada tekrar yayınlanan Türk şemaları Gs5b olmalıdır, çünkü şemada 3 jfet olduğu görülmüştür. Şemada gösterildiği gibi, Irf740'ı çalıştıran transistörün ucundaki direnç (470) doğruysa, transistör yanlıştır. Bu şekilde, Irf740'ı süremez. Bu konuda yayınlanan bilgilere göre Tx katı arızalı 470R daha önce belirttiğim direncin yandığını gösteriyor. bu şema ya hiç kimse yapmadı ya da sorunun farkında değil. Gs5'in orijinal mono bobin değerleri nedir? Kimse paylaşmadı ya da bir sır. Teşekkürler

[waltr]

[ATTACH]44817[/ATTACH]
[ATTACH]44818[/ATTACH]

These are NOT the same PCB's. Layout of each is completely different.
What Schematic are you using that Matches the PCB you have??

If you are burning a 470Ohm, 5Watt resistor then check for solder shorts with a good magnifier.

[ispanyol2]

[gaby_sult]

Post the schematic and PCB you have done, otherwise I have no solution for your problem.