Voodoo Main Discussion

[nickel_n]

Haha.. You noticed. I went about 6 1/2 turns for the bucking coil until it nulled, and since it's an open center shell I could not return the wire directly to the ending point across the center . But.. I found out if I thread it through a spoke and double back same way that the main TX coil runs it has just a minor effect on nulling. The rest can be fine tuned with a small loop.

I LOVE YOUR WORK

[SilverSurfer17]

Im curious why you didn't connect pin 1 and 5 on the pcb instead of in the connector ?

[dfbowers]

Right.. I might have written that document a few years ago. That build was for a White’s compatible coil where the frequency of the coil is dependent on the LC combination. The bucking coil will reduce the overall TX inductance and it’s a balancing act to get both right. I assume you are going off that document for building a coil for a hybrid or Voodoo? In that case I don’t believe that the TX inductance will matter that much as the coil is driven and a damping resistor is used instead of a tuning capacitor. The RX coil is the one you need to worry about tuning.

[dfbowers]

On that post that i was coping that coil off of he said this For the tricky part - When the bucking coil is wound around the Rx coil opposite direction from the Tx coil, the frequency goes up by about 60Hz, so a turn or 2 will have to be added to the Tx coil to bring the frequency back down to 6.59kHz. After tuning and nulling, the inner ring is filled with slow cure epoxy.

https://www.geotech1.com/forums/atta...3&d=1363497090

[SilverSurfer17]

Lol that makes 3 different sites its on

[MartinB]

Looks like the PIC on my Voodoo as stopped working. This afternoon I was playing with a new coil and scrolling through the Pulse settings when the display locked and push buttons had no effect. All I get on rebooting the board is the initialisation screen and then PULSE on the screen. There is no sync pulse on TP9 and no de-bug pulse. Has anyone else experienced this. If so, what was the cause. Thanks

[surfdetector]

Looks like the PIC on my Voodoo as stopped working. This afternoon I was playing with a new coil and scrolling through the Pulse settings when the display locked and push buttons had no effect. All I get on rebooting the board is the initialisation screen and then PULSE on the screen. There is no sync pulse on TP9 and no de-bug pulse. Has anyone else experienced this. If so, what was the cause. Thanks

Curious if you have both your +5V and -5V still?

[MartinB]

Curious if you have both your +5V and -5V still?

Hi Surfdetector
I have -5v but not +5v because I do not have the sync pulse from the pic to drive U8. I have swapped out both voltage regulators U6 and U7 just in case but it made no difference.
Battery voltage is 12.1V and sensor battery voltage on pic pin 10 is 4v but there is no battery voltage display on the LCD. I have ordered a replacement LT1054 for U8 but that won't be with me until Wednesday.

[6666]

then PULSE on the screen

Is that all that is on the screen ?
so this happened after you made changes in the settings ? are any of your buttons stuck down ? maybe you have hit a dead end in the code ?, but this is Georges baby,
as you have declared the chip dead even thou it is displaying some characters from within the software, I wonder if the chip would re program.

[MartinB]

Is that all that is on the screen ?
so this happened after you made changes in the settings ? are any of your buttons stuck down ? maybe you have hit a dead end in the code ?, but this is Georges baby,
as you have declared the chip dead even thou it is displaying some characters from within the software, I wonder if the chip would re program.

Hi 6666
Yes, this happened when I made changes. I was experimenting with pulse width - took PI pulse width up to 180us and the display locked. I have checked the buttons and all are OK. Maybe it is a software issue. I have ordered some replacement PIC's and a PICKIT 3 tonight with a view to interrogating the software and if necessary, programming a new PIC. This part is new ground for me so I hope it goes well

[SilverSurfer17]

Surf has a video that makes it pretty easy to understand but i have noticed in your past posts about voltages being lower than what some others have said theres where id look around that board top and bottom and make sure something isn't shorting or putting strain on the eprom

[6666]

Hi 6666
Yes, this happened when I made changes. I was experimenting with pulse width - took PI pulse width up to 180us and the display locked. I have checked the buttons and all are OK. Maybe it is a software issue. I have ordered some replacement PIC's and a PICKIT 3 tonight with a view to interrogating the software and if necessary, programming a new PIC. This part is new ground for me so I hope it goes well

Please keep us informed as to what you find, good luck.

[ionut_mtb]

Am I wrong or the Rx coil should be winded in counter clockwise direction?

[Qiaozhi]

Looks like the PIC on my Voodoo as stopped working. This afternoon I was playing with a new coil and scrolling through the Pulse settings when the display locked and push buttons had no effect. All I get on rebooting the board is the initialisation screen and then PULSE on the screen. There is no sync pulse on TP9 and no de-bug pulse. Has anyone else experienced this. If so, what was the cause. Thanks

From your description it appears that the PIC has either died or locked up.

What were the other settings when you had the TX pulse width set to 180us?
I suppose there's a possibility there's a conflict between a particular set of parameters. Once these get written into the EEPROM the PIC will crash, even when rebooted. The fact that the LCD displays "PULSE" before stopping, implies that this may be so. If that's the case, then reprogramming the PIC will reset everything back to normal. Before you do that, can you use the PICkit to extract the EEPROM contents? If you post them here it will give me a clue as to the problem.

I've not experienced any software issues myself, even when I just tried setting the width to 180us.

You could also try setting the first location in the EEPROM to $FF, without reflashing the PIC. This will tell Voodoo to write default settings into the EEPROM. If the detector then starts working again this is a clear indication that there's a parameter conflict somewhere. If that's the case I can fix that, but I will need to identify the problem first.

[MartinB]

From your description it appears that the PIC has either died or locked up.

What were the other settings when you had the TX pulse width set to 180us?
I suppose there's a possibility there's a conflict between a particular set of parameters. Once these get written into the EEPROM the PIC will crash, even when rebooted. The fact that the LCD displays "PULSE" before stopping, implies that this may be so. If that's the case, then reprogramming the PIC will reset everything back to normal. Before you do that, can you use the PICkit to extract the EEPROM contents? If you post them here it will give me a clue as to the problem.

I've not experienced any software issues myself, even when I just tried setting the width to 180us.

You could also try setting the first location in the EEPROM to $FF, without reflashing the PIC. This will tell Voodoo to write default settings into the EEPROM. If the detector then starts working again this is a clear indication that there's a parameter conflict somewhere. If that's the case I can fix that, but I will need to identify the problem first.

Hi George
Thanks for coming back to me.
Unfortunately, I can't remember what the other settings were.
As I have said previously, I am not familiar with PIC's or PICkit so I will do my best to extract the information you have requested. Hopefully it should be self explanatory