Voodoo Main Discussion

[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!

[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.

[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.

[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.

[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!

[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]

Fancy buying genuine brick... ?

[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...

[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.

[godigit1]

Awesome guys,
I was wanting to do the analog version as well based on a Mpp.
As I cant mod code yet.


Thanks Db for starting this and for your coil image it was all I needed to be able to build a concentric coil.

[ivconic]

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

Sounds like you still having quantum of doubts?

[ivconic]

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![ATTACH]54117[/ATTACH]The strangest what I caught from what you write how Voodoo works this detector has the same solution or very similar...

Shoosh! Say no more!

[Qiaozhi]

Sounds like you still having quantum of doubts?

No - we may just be talking at cross purposes, so I'm reserving judgement until I see the actual schematic. No conspiracy theory here.

[Qiaozhi]

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![ATTACH]54117[/ATTACH]The strangest what I caught from what you write how Voodoo works this detector has the same solution or very similar...

Is this your own design or someone else's?

[dfbowers]

PI disc experiment.

Here is what I have been playing around with. I can disc iron or non ferrous depending on where the sample it taken. The ground signal seems to have no overall effect. Since that original PI audio is left uncorrupted.. no double beep. All that is needed is to look at meter deflection. I can disc through two layers of brick and which is probably a stronger ground signal than my actual ground. It?s still on a breadboard but I can move my coil off the bench to a bed of bricks to test. If nothing else it had been a fun experiment!