Voodoo Main Discussion

[surfdetector]

George, do you have screen shots of test points 16 and 20 for the PI Channel Filter section? Thanks.

[Qiaozhi]

George, do you have screen shots of test points 16 and 20 for the PI Channel Filter section? Thanks.

If you go to Chapter 7 (page 81), TP16 should match the signal in the middle plot of Fig. 7-4, and TP20 should match the signal in the bottom plot.

By the way, PL7 and PL8 should always be set as in Fig. 4-4. These jumpers are only there for flexibility if someone wants to experiment with different coils. It's possible there may be an occasion where the RX loop signal is inverted (although I never found one), and the PI channel can be inverted to match it. However, it will also require an alteration to the firmware to invert the detection of the channel outputs.

Once someone manages to successfully replicate the Voodoo Project, I will upload the source code to post #1.

[MartyJ1963]

Thanks George. @6666,,The points I asked about are not printed on the silkscreen,,if they are there, and I missed them, I can't see them through the black colour,,,but I thought I'd play it safe,,when in doubt ask. Hope your wife is well mate. Regards, Marty.

[Qiaozhi]

Thanks George. @6666,,The points I asked about are not printed on the silkscreen,,if they are there, and I missed them, I can't see them through the black colour,,,but I thought I'd play it safe,,when in doubt ask. Hope your wife is well mate. Regards, Marty.

The pin numbers are not shown on the silkscreen. That was an oversight.
However, it is possible to work out the correct orientation by noting that pin 3 on both PL7 and PL8 are connected to ground (0V).

[MartyJ1963]

Thanks again George. Not had a lot of free time in the last few days and stll studying which enclosure to use but I should have some more completed some tme this week. Regards, Marty.

[sbalio1]

hi to all friends is there enny hex file for this machine

[6666]

hi to all friends is there enny hex file for this machine

See first post

[6666]

Thanks George. @6666,,The points I asked about are not printed on the silkscreen,,if they are there, and I missed them, I can't see them through the black colour,,,but I thought I'd play it safe,,when in doubt ask. Hope your wife is well mate. Regards, Marty.

Hi Marty, no they are not printed on the silk screen, thats the problem, my statement was a request for them to be added,
my missus is out of hospital, but its going to be long recovery, thanks

[MartyJ1963]

Hi 6666,,,,it would be nice to see them on the silk screen but I'm ok now I've printed off a reference diagram. Best wishes to you and your wife for a good recovery,,Regards, Marty.

[surfdetector]

I completed the PI demodulator portion of the circuit and when testing at TP7 and TP8 I get a decrease in voltage when passing metal over the coil. Is that correct or should the voltage level increase?

[Qiaozhi]

I completed the PI demodulator portion of the circuit and when testing at TP7 and TP8 I get a decrease in voltage when passing metal over the coil. Is that correct or should the voltage level increase?

At TP8 you should see a decrease for all targets. At TP7 there will also be a decrease, but of much lower amplitude as this is the EFE (late) sample.

[surfdetector]

At TP8 you should see a decrease for all targets. At TP7 there will also be a decrease, but of much lower amplitude as this is the EFE (late) sample.

That is exactly what I have on my project. I was confused because on page 29 it states in part, for TP7 and TP8 " the demodulated main signal amplitude increases in the presence of a target....."
Thanks.

[Qiaozhi]

That is exactly what I have on my project. I was confused because on page 29 it states in part, for TP7 and TP8 " the demodulated main signal amplitude increases in the presence of a target....."
Thanks.

Yes, I know. That was an error.
Keep an eye on post #1 where I've posted some hints and an errata.

[MartyJ1963]

Hi George,,,Thanks for the additions/Errata to post #1,,much appreciated. Regards, Marty.

[6666]

That is exactly what I have on my project. I was confused because on page 29 it states in part, for TP7 and TP8 " the demodulated main signal amplitude increases in the presence of a target....."
Thanks.

So we need to change wording on page 29 and add to post #1, good to see these things being found.