My Raptor project

[ozzy123]

Hi, i'm start to build a Raptor MD project with my
NEL Hunter Coil for Tesoro Cortes. (5 pin.)

I just finished pcb and I have some questions:

1. What should be the frequency of generator operation ?
2. What should be the resonant frequency of L1 C1 circuit ?

[Qiaozhi]

Hi, i'm start to build a Raptor MD project with my
NEL Hunter Coil for Tesoro Cortes. (5 pin.)

I just finished pcb and I have some questions:

1. What should be the frequency of generator operation ?
2. What should be the resonant frequency of L1 C1 circuit ?

The TX frequency is 10kHz.
Since you are building the Raptor project, I assume you have a copy of the book.
All the information you need is provided in Chapter 9 of -> Inside the METAL DETECTOR - Second Edition - Published 2015

[ozzy123]

I have a original book - not a copy.

Indeed, in Chapter 9 on page 85, it is stated that the frequency Tx is 10 kHz.
However, from the theoretical calculations for the Tesoro coil used in the book, it follows that:

Tx 5.9 mH + C1 43 nF gives a frequency 10.85 kHz
Rx 6.5 mH + C2 33nF gives resonant frequency 11.31 kHz

I was a little lost.

Information about these frequencies is needed to select the right frequency Tx and Rx for my Nel Hunter coil.

I measured the inductance with a RLC bridge and they are in my coil respectively:

Tx 5.59 mH
Rx 5.98 mH

In conclusion: for the frequency Tx 10.00 kHz what should be the property resonance frequency of Rx?

[Qiaozhi]

I have a original book - not a copy.

When someone says that they have a "copy" of a book, it simply means that they have the book. If it's a physical book, then you would call it a "printed copy". If it's an e-book, then it's an "electronic copy". Only the authors have the "original" book. If you buy ITMD from Amazon, then it's a copy. They are all copies. Perhaps it's just an English thing, as I've seen other people get confused by the term.

Indeed, in Chapter 9 on page 85, it is stated that the frequency Tx is 10 kHz.

The design aim was to achieve 10kHz, or close to that frequency. The exact frequency doesn't really matter that much.

However, from the theoretical calculations for the Tesoro coil used in the book, it follows that:

Tx 5.9 mH + C1 43 nF gives a frequency 10.85 kHz
Rx 6.5 mH + C2 33nF gives resonant frequency 11.31 kHz

The resonant frequency calculations are:


and

I was a little lost.

Information about these frequencies is needed to select the right frequency Tx and Rx for my Nel Hunter coil.

I measured the inductance with a RLC bridge and they are in my coil respectively:

Tx 5.59 mH
Rx 5.98 mH

In conclusion: for the frequency Tx 10.00 kHz what should be the property resonance frequency of Rx?

You can calculate the value of capacitance required using this equation:



where

For the NEF coil: and
In that case I would probably chose 47nF and 33nF. Although you can parallel different values to obtain a more accurate result, you don't have to be that pedantic about the accuracy of the capacitance values.

[ozzy123]

Thank you Qiaozhi for help. Actually I made the mistake of calculating frequencies.
My fault. I will report progress on the construction of the Raptor.
Below are photographs showing the progress of the work and the NEL Hunter coil used.







Nicodemus (Nico) also helps in the construction of the detector:

[Nandor]

Hello ozzy nice work you done, i have a cat too
What king of MD is the Raptor? It's deep or good discriminator?

[ozzy123]

Some information You find in this thread :

http://www.geotech1.com/forums/showthread.php?19890-Raptor-schematic&highlight=raptor

[ozzy123]

Next step.

I soldered the next items according to the instructions in the book.

Tx frequency is 10,04 kHz
Rx resonant frequency is 10,98 kHz


Tx amplitude is 17 Vpp


Rx amplitude is 450 mVpp


Both oscilograms.


Are the signal amplitudes correct?
Are the phase shift correct?

I'm particularly worried about the amplitude Rx = 450 mV.
According to the book should be in the range of 120-250 mV

[Qiaozhi]

From the scope image it looks like the difference between the negative-going edge of the TX signal and the positive-going edge of the RX signal is around 10 degrees. On a standard Tesoro coil this offset is 20 degrees. Try adjusting the TX/RX overlap and see if the offset voltage drops.

Also, when you say the "RX resonant frequency is 10.98 kHz", is this as measured on the scope when the TX is operating? Note that even if the RX inductance and parallel capacitance resonant at [for example] 11kHz, the frequency measured at the receiver will still be the same as the TX.

[ozzy123]

"Try adjusting the TX/RX overlap and see if the offset voltage drops."

I can not correct the position of the coils Tx-Rx with respect to each other - as I wrote before don't use homemade coil -
I use the factory ready NEL Hunter coil for Tesoro Cortes.

RX resonant frequency is 10.98 kHz - I have chosen this frequency for the LC circuit using a tuned signal generator and oscilloscope.

I know that the frequency measured at the receiver is the same as the transmitter frequency.

[Qiaozhi]

"Try adjusting the TX/RX overlap and see if the offset voltage drops."

I can not correct the position of the coils Tx-Rx with respect to each other - as I wrote before don't use homemade coil -
I use the factory ready NEL Hunter coil for Tesoro Cortes.

Sorry - I forgot.

RX resonant frequency is 10.98 kHz - I have chosen this frequency for the LC circuit using a tuned signal generator and oscilloscope.

I know that the frequency measured at the receiver is the same as the transmitter frequency.

In that case, try moving the RX resonant frequency further away from the TX so that you have an offset of 20 degrees instead of 10.

[ozzy123]

Several new components have been found on the PCB.



And I did the tasks of points 11 and 12 - these are the results of regulation:



Disc offset



Geb offset

I think it is OK

[Qiaozhi]

Several new components have been found on the PCB.



And I did the tasks of points 11 and 12 - these are the results of regulation:



Disc offset



Geb offset

I think it is OK

Looking good.

[Tibuck19]

How did it finish ? was the MD completed and field tested ? has anyone else besides Ozze made this ? Is it better then the TGSL and IDX or about the same or worst loll