The Moodz detector lives !

[crane]

... well its exactly as I said ... Ferrite does not impact target sensitivity ... or ferrite rejection is good. Take your pick :-)

So you don't wish to say how you reject the ferrite?

A conventional PI ignores the ferrite X signal by delaying the early sample until after the spike has fully decayed. You though say you are sampling the ferrite X signal but are somehow ignoring it??

I'm sure others here are also confused.

Do you have a video showing the viscous (VRM) ground signal?

[6666]

I have grown tired of secret squirrel detector projects so very shortly I will gather the documents and publish my design for a kickass PI detector.

Are there any documents that can be published yet ? all watching with great interest.

[moodz]

... well its exactly as I said ... Ferrite does not impact target sensitivity ... or ferrite rejection is good. Take your pick :-)

[crane]

...so I played with the timings a bit and the ferrite rejection is good ( in terms of audio output ... ) and the target sensitivity is still good also.

https://www.youtube.com/watch?v=UHBV2hZrivo

In this video the ferrite is right on the coil ... hence the massive changes in X signal ... however the R signal is still very sensitive.

Moodz says "despite several volts of change on the sampled waveform we are getting very little audio change". He appears to be saying he is actually sampling the several volts of change, or has he delayed the sample until after the ferrite's (x) signal has almost settled?

It would be nice if he could clear this up.

[BILLY]

Moodz was led astray by Doug (the mouthpiece of the QED) and was told by Doug that he was going to have the best detector ever made. Poor Moodz I am sure is rethinking his mentor Doug. So to answer your question, Moodz has nothing that is not already out there much cheaper. Sorry if the truth hurts.

[soverey]

Any news about the progress towards a commercial kit? , hope it wasn't just a display of technology , like seen before in some threads on this forum.

[BILLY]

I also wonder how the coils you were making and going to produce many a day. And news on that?

[soverey]

Any progress towards a commercial kit ?

[Chet]

I agree it's very impressive,
Have a good day,
Chet

[Geo]

very good.....

[moodz]

...so I played with the timings a bit and the ferrite rejection is good ( in terms of audio output ... ) and the target sensitivity is still good also.

https://www.youtube.com/watch?v=UHBV2hZrivo

In this video the ferrite is right on the coil ... hence the massive changes in X signal ... however the R signal is still very sensitive.

[Davor]

Discrimination hole may be avoided by toggling two or more ground balanced delays, but there is another catch - a phase reversal beyond hole. If design includes an absolute value circuit - no problem. Otherwise you'll see targets beyond a hole only with phase reversed, i.e. outside the coil loop.

[Geo]

It would be interesting and for me too a schematic or a pcb or a kit....

[Orbit]

Hello Moodz place the pcb in scheme so that we all ascertain whether it's worth if you do not I think we have no right I'm looking for too much of Moodz ! All the best !!

[Chet]

Hi Moodz


I am very impressed with your detector. And appreciate you sharing it with us. I offer the following comments in reply to your questions:


“... thanks for all comments ... the current design only has one channel ( or two depending on your point of view ) ... was not expecting the discrimination frontend to work so well for this version. With "one" channel I can sample X or R or some subtractive combination ... however any sort of subtraction is probably going to leave a target hole. So I am leaning towards two tone .... one tone ( channel X ) for X and one tone ( channel R ) for R similar to some VLF detectors ... will this be effective ?”


If there is a target hole could the position be selected or movable by the builder? Discrimination is never fool proof because of size, shape and different target time constants for the same metal. I think the tone option would be the most effective.


“Will need to add the additional channel hardware to the design at any rate...( re-lay the PCB ) .... maybe the handling of X and R can be user configurable ?”


If possible I think having an all metal option dependent on the builder’s choice is a good way to go.


“The current design is surface mount ... makes the PCB cheaper but trickier assembly for some constructors ?”


This is probably the most important decision to make. For some of us surface mount is just not doable. For me Carl’s Hammer Head surface mount board was beyond my capability. Any mistake or repair or design change sometimes leads to starting over with a new board and new components. If you can see your way to providing a standard through the hole board I believe it will please many of us.


“Probably should also note that gains in the signal chain are only set to 20% of potential and timings are also conservative ... could decrease sampling time by 60% at least ( sub 3 us ?) for very small targets.”


I think providing build options such as different resistor values to adjust gains and sample times is a benefit. Having the ability to sample as early as 3us is fantastic for gold hunters.


“Hot ground and salt water tests for discrimination ?? May need DD coil / fig 8 coil ?? Change sampling or gain ?? Cant answer just yet.
DD coils etc ...?? Only tested for MONO coils ( I like mono coils ;-) because they are "pure" coils ) ... however need to add additional channel(s) to board for these also ??”


I don’t think an additional channel is needed. A jumper option to use a MONO coil or a coil with a separate receiver winding should be acceptable. This would allow various two coil arrangements to be used. Are you using your differential frontend? It would be useful to use a separate transmitter coil with an isolated separate center tapped receiver coil.


Thank you for sharing this with us and have a great day,
Chet