Voodoo Main Discussion

[dingbatca]

Correction. TP15 was reading +4.96V. Now it's reading -0.8V. I swapped out the 78L05 (U7) thinking I was having a regulator issue. No luck, still reading -0.8v. Any ideas? Pics attached.

[dingbatca]

Arg! TP15 is reading -0.8v... It was reading -4.96v when I built the circuit. Looks like I blew something out. :-(

[Qiaozhi]

DFX coil attached. But TP5 has me stumped. I feel like I am missing something critical, but for the life of me I cant seem to find it. Pic's attached.

TP5 is the output of the first stage of the PI preamp, so there's some very basic fault here. Are you sure you have a +5V supply?

[dingbatca]

DFX coil attached. But TP5 has me stumped. I feel like I am missing something critical, but for the life of me I cant seem to find it. Pic's attached.

[Qiaozhi]

It's a good day! I finished the board build and testing... Well, as far as I can go with out a proper coil.

Would a Whites DFX coil work? This is the classic DFX round coil. Pin out in this thread.

The chart provided on page 75 does a great job of covering a wide range of coils. Any tips on adapting this coil?

White's DFX concentric
Rx 1,2 13.8mH 36 ohms
Tx 4,5 540uH 2.7 ohms

Pin1 RX shield
Pin2 RX
Pin3 NC
Pin4 TX
Pin5 TX shield

TX Coil:
L--> 548,5uH
Q--> 1,27
C--> -46,15uF
R--> 2,72 Ohmios
Rx Coil:
L--> 13,6mH
Q--> 2,16
C--> -1,86uF
R--> 94 Ohmios

Looking at the specifications I would say "yes".
The TX inductance is in the accepted range. If the coil is well balanced (and I expect it will be) then there should be no ringing at the PI preamp output due to the RX loop. A parallel capacitor across the RX loop of 470nF will give an frequency of 10kHz.

[dingbatca]

It's a good day! I finished the board build and testing... Well, as far as I can go with out a proper coil.

Would a Whites DFX coil work? This is the classic DFX round coil. Pin out in this thread.

The chart provided on page 75 does a great job of covering a wide range of coils. Any tips on adapting this coil?

White's DFX concentric
Rx 1,2 13.8mH 36 ohms
Tx 4,5 540uH 2.7 ohms

Pin1 RX shield
Pin2 RX
Pin3 NC
Pin4 TX
Pin5 TX shield

TX Coil:
L--> 548,5uH
Q--> 1,27
C--> -46,15uF
R--> 2,72 Ohmios
Rx Coil:
L--> 13,6mH
Q--> 2,16
C--> -1,86uF
R--> 94 Ohmios

[sbalio1]

Thanks Qiaozhi good wiches.

[Qiaozhi]

Iam hearing that this metal detector vodoo is sensible for eron so what about gold and other metal. Can ennyone here anser me.

Everything is described in some detail in the book.
Voodoo is designed to reject iron and to accept all other metals.
Read post #1.

[Tibuck19]

The Voodoo Project requires 4 push buttons, but I would suggest you ask Andy directly in case he is interested.

Okie, i did not know it needed 4, then this are useless for this project, no sense hassling Andy about them.

[sbalio1]

Iam hearing that this metal detector vodoo is sensible for eron so what about gold and other metal. Can ennyone here anser me.

[Qiaozhi]

from the Arduino Pi thread

I have close to a bakers dozen of these lcd 16x2 with push buttons on the boards. I have not really been doing anything with them. If you think they might be useful i could always box them and send them to Andy to pass off in Voodoo board component kits of if he decides to make kits.


[ATTACH]54697[/ATTACH]
[ATTACH]54698[/ATTACH]
[ATTACH]54699[/ATTACH]

The Voodoo Project requires 4 push buttons, but I would suggest you ask Andy directly in case he is interested.

[Tibuck19]

from the Arduino Pi thread

I'm not sure whether to keep the OLED support though, as the 1.3" display is tiny compared to the LCD, and the library consumes a lot of memory even when configured in non-buffered mode.
If anyone has any thoughts on this subject, then please continue discussions in the Voodoo Project thread.

I have close to a bakers dozen of these lcd 16x2 with push buttons on the boards. I have not really been doing anything with them. If you think they might be useful i could always box them and send them to Andy to pass off in Voodoo board component kits of if he decides to make kits.

[SilverSurfer17]

That was with a mono coil connected thats the only way it looked right with the concentric coil connected with just using the tx as a mono it was seeing the rx coil as a target it made the square wave wavy ill take a pic and post it of the signal later today thanks surf

[surfdetector]

That was with the resistor installed but the resistor i had to use was lower than anything mentioned and that could be its still not detecting anything yet but i haven't messed with the rx circuit yet or bucked the tx to rx yet im going by the steps mentioned

You should wind a simple mono coil on its own in order to better trouble shoot the issues you are having with your project. After you wind it and connect it to the TX on PL1 connect your probe and take a picture of the flyback wave form. Set your scope to 50V and 25uS and your probe to 10x.

[SilverSurfer17]

That was with the resistor installed but the resistor i had to use was lower than anything mentioned and that could be its still not detecting anything yet but i haven't messed with the rx circuit yet or bucked the tx to rx yet im going by the steps mentioned