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The Voodoo Project <<- Click to view book on Amazon
A Pulse Induction Metal Detector with Iron Discrimination
Pulse induction metal detectors are very sensitive to ferrous (iron) targets, and one that can ignore iron has been a sort of holy grail for metal detector developers for some time.
The Voodoo Project is a written record of the author's personal mission to design and develop a working pulse induction (PI) metal detector that is capable of good iron rejection.
Voodoo is a hybrid detector with features of both a PI and a VLF. The design goal was to develop a PI that can be used both inland and on the beach. In particular, special attention was devoted to finding non-ferrous targets in areas infested with ferrous trash. Rejection is not based on target conductivity, as Voodoo provides true ferrous/non-ferrous discrimination.
This book is available worldwide from Amazon.
If you are having problems ordering a copy of the book from Amazon in your particular country, the Book Depository can supply copies with free delivery worldwide.
https://www.bookdepository.com/Voodo...6996899&sr=1-1
The Gerber files can be sent to a PCB manufacturer such as JLCPCB.
Notes:
1. The LCD (U4) pinout on the PCB is pin #1 on the right-hand side (next to the ref des U4) and pin #16 on the left-hand side (as viewed from the top of the PCB).
Arduino Nano Variant:
Anyone interested in an Arduino Nano variant, that uses a small adapter PCB to replace the original PIC18F4520, should go to post #1460.
https://www.geotech1.com/forums/show...883#post287883
Updates:
1. MartinB discovered that setting the TX pulse width to 180us, and the main sample delay to 49us caused the detector to lockup requiring the PIC to be re-flashed. Software Version 1.1 below fixes this issue. Also, the max TX pulse width was increased to 200us, and the min main sample delay reduced to 10us.
2. Carl noticed a bug in the menu system where it is supposed to restrict the disc sample from going over 100us. Unfortunately it was changing the main sample instead. Software Version 1.2 below fixes this issue.
3. If you experience a problem where the +5V supply is not working, but the LT1054 output is OK, then put a reverse-biased diode ( 1N4148 ) across the output of the 78L05 voltage regulator. A few Geotech members have encountered this issue when using low quality or old stock regulators from some suppliers. The problem is caused by latch-up within the regulator. Latch-up does not appear to affect newer products.
4. Carl has ported the original Mikro-C code to the Microchip XC8 compiler. You can find the source code and some discussions here -> XC8 C code
5. Don (dfbowers) has a created a short video demonstrating the Voodoo detector operating in both PI and DISC modes -> https://youtu.be/8dC6jkkSNBo
6. You can find the schematics here -> https://www.geotech1.com/forums/show...838#post293838
"A person who never made a mistake never tried anything new." - Albert Einstein
Errata:
1. Page 19, PL7 and PL8 jumpers should be connected to pins 2/3 (PL7) and 1/2 (PL8 ). Pin #1 is at the top for both jumpers. See Fig. 4-4.
2. Page 22, Figs 3-7 and 3-8 are swapped over.
3. Page 29, TP5 - reference should be to Fig. 3-16.
4. Page 29, TP7 and TP8 should state that the amplitude decreases in the presence of a target.
5. Page 88, Component Parts List (Miscellaneous) - speaker / headphones should be high-impedance.
A Pulse Induction Metal Detector with Iron Discrimination
Pulse induction metal detectors are very sensitive to ferrous (iron) targets, and one that can ignore iron has been a sort of holy grail for metal detector developers for some time.
The Voodoo Project is a written record of the author's personal mission to design and develop a working pulse induction (PI) metal detector that is capable of good iron rejection.
Voodoo is a hybrid detector with features of both a PI and a VLF. The design goal was to develop a PI that can be used both inland and on the beach. In particular, special attention was devoted to finding non-ferrous targets in areas infested with ferrous trash. Rejection is not based on target conductivity, as Voodoo provides true ferrous/non-ferrous discrimination.
This book is available worldwide from Amazon.
If you are having problems ordering a copy of the book from Amazon in your particular country, the Book Depository can supply copies with free delivery worldwide.
https://www.bookdepository.com/Voodo...6996899&sr=1-1
The Gerber files can be sent to a PCB manufacturer such as JLCPCB.
Notes:
1. The LCD (U4) pinout on the PCB is pin #1 on the right-hand side (next to the ref des U4) and pin #16 on the left-hand side (as viewed from the top of the PCB).
Arduino Nano Variant:
Anyone interested in an Arduino Nano variant, that uses a small adapter PCB to replace the original PIC18F4520, should go to post #1460.
https://www.geotech1.com/forums/show...883#post287883
Updates:
1. MartinB discovered that setting the TX pulse width to 180us, and the main sample delay to 49us caused the detector to lockup requiring the PIC to be re-flashed. Software Version 1.1 below fixes this issue. Also, the max TX pulse width was increased to 200us, and the min main sample delay reduced to 10us.
2. Carl noticed a bug in the menu system where it is supposed to restrict the disc sample from going over 100us. Unfortunately it was changing the main sample instead. Software Version 1.2 below fixes this issue.
3. If you experience a problem where the +5V supply is not working, but the LT1054 output is OK, then put a reverse-biased diode ( 1N4148 ) across the output of the 78L05 voltage regulator. A few Geotech members have encountered this issue when using low quality or old stock regulators from some suppliers. The problem is caused by latch-up within the regulator. Latch-up does not appear to affect newer products.
4. Carl has ported the original Mikro-C code to the Microchip XC8 compiler. You can find the source code and some discussions here -> XC8 C code
5. Don (dfbowers) has a created a short video demonstrating the Voodoo detector operating in both PI and DISC modes -> https://youtu.be/8dC6jkkSNBo
6. You can find the schematics here -> https://www.geotech1.com/forums/show...838#post293838
"A person who never made a mistake never tried anything new." - Albert Einstein
Errata:
1. Page 19, PL7 and PL8 jumpers should be connected to pins 2/3 (PL7) and 1/2 (PL8 ). Pin #1 is at the top for both jumpers. See Fig. 4-4.
2. Page 22, Figs 3-7 and 3-8 are swapped over.
3. Page 29, TP5 - reference should be to Fig. 3-16.
4. Page 29, TP7 and TP8 should state that the amplitude decreases in the presence of a target.
5. Page 88, Component Parts List (Miscellaneous) - speaker / headphones should be high-impedance.
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