Voodoo Main Discussion

[Qiaozhi]

The signal from the PI circuit is extracted before the SAT on my circuit. It really has no effect..

OK - I'll wait until you send me the schematic.

[Orbit]

I wonder the same similar detector it has been around for almost a year ! As if all at once in several places give birth to the same ideas.Hybrid detector images works perfectly..but I can't give more information will appear this year!The strangest what I caught from what you write how Voodoo works this detector has the same solution or very similar...

[ivconic]

Fancy buying genuine brick... ?

[dfbowers]

I would be very interested to study your schematic. The spawning of other variations is exactly what I hoped Geotech members would do.

However, I believe you may encounter problems when used on real ground with SAT in the PI channel, and double-diff in the DISC channel. Have a look at Fig. 7-4, and compare the Outer signal in pane 1 with the DISC signal in pane 3. For a non-ferrous target the outer lobes on the DISC signal go negative, so everything is fine. But ... for a ferrous target the outer lobes on the DISC signal go positive, and you get a double beep. There is no effective ferrous rejection. This is why both channels need to be double-differentiated.

The signal from the PI circuit is extracted before the SAT on my circuit. It really has no effect..

[ivconic]

I would be very interested to study your schematic. The spawning of other variations is exactly what I hoped Geotech members would do.

However, I believe you may encounter problems when used on real ground with SAT in the PI channel, and double-diff in the DISC channel. Have a look at Fig. 7-4, and compare the Outer signal in pane 1 with the DISC signal in pane 3. For a non-ferrous target the outer lobes on the DISC signal go negative, so everything is fine. But ... for a ferrous target the outer lobes on the DISC signal go positive, and you get a double beep. There is no effective ferrous rejection. This is why both channels need to be double-differentiated.

"...The spawning of other variations is exactly what I hoped Geotech members would do..."

I said that too. That's the main value of your work in the book.

"...I believe you may encounter problems when used on real ground with SAT in the PI channel, and double-diff in the DISC channel..."

That's why i asked about the bricks.

C'mon George! Stop copying my thoughts!
Are we the telepathy connected twins by some strange misfortune???





P.S.
Me Reggie and you Ron Kray!

[Qiaozhi]

George do you think Dons project could be viable if it does not infringe your IP too much ?
I have both books by the way.

See my reply in post 859.

I give Don's experiments my full support.

[Qiaozhi]

My original PI circuit uses a SAT for the audio threshold.. that’s it. For the disc channel I’m using a single ended diff amp same method you use for the VooDoo. For the Disc channel, I’m pulling from the main clock on of the PI detector and using Schmitt triggers to adjust delay and sample width. Then just merge the channels with LM393s. I think I could get it to work on the Baracuda, Hammerhead or Surf PI.. I had to change a few thing on your disc channel though because the frequency response was different between my PI circuit and what you have in your book. I had to change the gains a little as well. It completely ignores brick which I think is close to a real ground signal. That makes me feel optimistic. I will clean up my schematic and send it to you .

I would be very interested to study your schematic. The spawning of other variations is exactly what I hoped Geotech members would do.

However, I believe you may encounter problems when used on real ground with SAT in the PI channel, and double-diff in the DISC channel. Have a look at Fig. 7-4, and compare the Outer signal in pane 1 with the DISC signal in pane 3. For a non-ferrous target the outer lobes on the DISC signal go negative, so everything is fine. But ... for a ferrous target the outer lobes on the DISC signal go positive, and you get a double beep. There is no effective ferrous rejection. This is why both channels need to be double-differentiated.

[ivconic]

... Also.. Resonant frequency of the RX channel doesn?t seem to matter much as long as the sample delay and sample pulse can be adjusted to sample at the correct time...

This is good news.
This will simplify coil making and adjusting.

[ivconic]

My original PI circuit uses a SAT for the audio threshold.. that?s it. For the disc channel I?m using a single ended diff amp same method you use for the VooDoo. For the Disc channel, I?m pulling from the main clock on of the PI detector and using Schmitt triggers to adjust delay and sample width. Then just merge the channels with LM393s. I think I could get it to work on the Baracuda, Hammerhead or Surf PI.. I had to change a few thing on your disc channel though because the frequency response was different between my PI circuit and what you have in your book. I had to change the gains a little as well. It completely ignores brick which I think is close to a real ground signal. That makes me feel optimistic. I will clean up my schematic and send it to you .

Very interesting.
Qiaozhi's book will generate many similar ideas and projects.
I think that's the major value of it.
Those bricks... i wonder are those any close to ancient Roman bricks that we have here.
Have you checked those and their magnetic features?
If those are similar to ancient Roman bricks... than you made HUGE success!

[6666]

It's not easy to tell from the video whether you're using a simple SAT, or single, or double-differentiating filters.
I've also tried analog versions of Voodoo with varying degrees of success.

George do you think Dons project could be viable if it does not infringe your IP too much ?
I have both books by the way.

[dfbowers]

My original PI circuit uses a SAT for the audio threshold.. that’s it. For the disc channel I’m using a single ended diff amp same method you use for the VooDoo. For the Disc channel, I’m pulling from the main clock on of the PI detector and using Schmitt triggers to adjust delay and sample width. Then just merge the channels with LM393s. I think I could get it to work on the Baracuda, Hammerhead or Surf PI.. I had to change a few thing on your disc channel though because the frequency response was different between my PI circuit and what you have in your book. I had to change the gains a little as well. It completely ignores brick which I think is close to a real ground signal. That makes me feel optimistic. I will clean up my schematic and send it to you .

[Qiaozhi]

While waiting for my PCB and PIC to arrive I decided to build a concentric except I went for a more conventional 360uH TX and 6.9mH RX coil. To test it I attached it to a modified Surf PI Pro with a split TX and RX. To my amazement it worked great for a disc channel but required reduced gain. So I figured why not just build a separate disc channel and have an analog version of the VooDoo? I am just using the existing PI channel as an equivalent GB channel and borrowed some of George?s idea from the VooDoo project. I am just merging the two channels just like the Raptor, TGSL or Whites classic with a pair of LM393s. The only real challenge was getting the frequency response of the GB and disc channels close to the same. Also.. Resonant frequency of the RX channel doesn?t seem to matter much as long as the sample delay and sample pulse can be adjusted to sample at the correct time.
Too many ideas from on George?s books to post here but I can show that it works.
https://youtu.be/9aqxGrFK9fo


So, here is a little demo of how it works. It deals with the ground signal quite well and can disc iron with an analogue meter.

It's not easy to tell from the video whether you're using a simple SAT, or single, or double-differentiating filters.
I've also tried analog versions of Voodoo with varying degrees of success.

[6666]

I think so.. I will run it past George. I can have him look at the schematic once I clean it up.
As far as the actual schematic there is nothing special. His original concept is used though.. just did it in analog.

Excellent, thanks.

[dfbowers]

Good work thanks for the info. Could it turn into a group project ???

I think so.. I will run it past George. I can have him look at the schematic once I clean it up.
As far as the actual schematic there is nothing special. His original concept is used though.. just did it in analog.

[6666]

While waiting for my PCB and PIC to arrive I decided to build a concentric except I went for a more conventional 360uH TX and 6.9mH RX coil. To test it I attached it to a modified Surf PI Pro with a split TX and RX. To my amazement it worked great for a disc channel but required reduced gain. So I figured why not just build a separate disc channel and have an analog version of the VooDoo? I am just using the existing PI channel as an equivalent GB channel and borrowed some of George’s idea from the VooDoo project. I am just merging the two channels just like the Raptor, TGSL or Whites classic with a pair of LM393s. The only real challenge was getting the frequency response of the GB and disc channels close to the same. Also.. Resonant frequency of the RX channel doesn’t seem to matter much as long as the sample delay and sample pulse can be adjusted to sample at the correct time.
Too many ideas from on George’s books to post here but I can show that it works.
https://youtu.be/9aqxGrFK9fo


So, here is a little demo of how it works. It deals with the ground signal quite well and can disc iron with an analogue meter.

Good work thanks for the info. Could it turn into a group project ???