If you use spiral is more sensitive, but strong telluric currents can be detected with it.

Here an handmade spiral finish recently. Hardzarous to winding. Winding and paste, winding and paste...

With round loop.

Coil tesla
 

This kind of spiral coils are very easy for winding Esteban,if you use special and easy tecnique,just start the spiral coil between two wood circles with the desired wire expessor(can control this with screw in the midle),and when finish winding take out the circle from the top,put glue on wire turns ,et voyla ;)

Maybe... maybe

Hi Esteban.
Some questions :):)
1.At this magnetic field detector is it practical to reconect the reading leds and to work only with the speaker????
2. Do you think that it is a good choise (if i construct it) to find a big treasure??? or it is better the passive receiver
3. At who distance (max) it can (if it can) locate a big treasure of gold (50x50x50 cm )??

Regards:)

Hi Geo

1. In general, the first led is on (adjusted with the 10 K preset). But I think is better one external pot. for to leave on this led. The other potentiometer is for to manage the audio. This last is your sensibility control. You don't use here piezo sounder. Instead it you use a beeps generator for to catch the small variations.

2. Is only receiver. Is very good for treasures, don't fail is treasure is 30 meters of the loop. The 150 silver knives, spoons, etc., posted on another thread (but show only 3 of these –I'm waiting the photo of treasure taken in cellular phone–) was found with it!

3. Respond on point 2.

In general, tends to be most sensitive for silver.


Regards

Esteban

You can see here toroidal coils I use on it. I saved from old PCBs, first these!

When battery of this circuit is low, led and audio come crazy, so this "natural" advisor is an advantage. My big THANKS to Andy Flind! :) :)

Hi Esteban:).
The problem is that at my City i can't find the LM3915.
If it is better from passive receiver i will give it a try.
At who distance did you found the silver knives, spoons, etc?????
Also at one photo from you i saw inside a FM radio again????
What about it??? Did you found the silver knives with the radio inside or no??
Regards:)

I believe that the coils here have many turns for this circuit. We want a transformer with Z1 as the z0 of the Loop and Z2 the total resistance of the transformer 2x6v/100ma
Regards:)

So is it better to work with lower voltage and biger serial resistance????

Maybe you can replace by LM3914, but this is lineal in voltage, not logaritmic.

A friend found by similar machines based on this circuit. He found at 30 m, buried 1.30 meters. I put the radio inside, but is not necessary. Yes, the detection was with radio inside, but also without radio I found several times objects with it. I like it because this is some reluctance to detect riffle cartridges, for example, but round buttons silver, bronze, etc., coins and other things are detectable.

No, is a coil wound in core, only 2 ohms. You can't use here transformer, this is not useful for the pistol and because with transformer interferences of electric lines is a poison!

The voltage indicates for circuit is OK, but I use AA batteries, no the rectangular 9 V. I think, but I not try, to use resistor for each led for reduction of consumption.

Thank you Esteban.
Maybe next week to have time to try it
My regards:)

Maybe you have saved the constructional of aluminiun loop and core. This I post time ago, but here repost.

Regards

Hi Esteban,
I saw this picture from you... posted on page 2 of this thread...

Now... I know that circuit cause was employed in a pinpointer stuff (russian schematic based on that magazine too, I think first time I saw it was around 1989, is that possible ?) but know for use in pinpointers not LRL. I remember there's a lowered amplitude when e.g. iron is near...

Now this that's really surprising to me... see that stuff used for LRLs too I mean! It's very basic circuit , kind of hartley osc...:rolleyes:

Which kind of signal variations you read in presence of a gold target ?

And which is the range you noticed from it LRL behaviour in relationship with which target/size ?

Kind regards,
Max

This is not the only circuit. This works as resonance off. Amplifier circuit uses a LM358 and 4066. Also a radio and beeper, so is 2 detector in one.

Distance for small things can be 5 m, a treasure can be detected at 30 m.

I don't read nothing, I hear the beeps! :lol:

Hi,
yes... but you provide data for coil... but not the other stuff... :D

Don't understand why you post coil data and then nothing else... so the thing you posted is just an oscillator !?

So... why ?

Ok, your choice... but that's not easy belive it can be used with success in real, working LRL... it's really low power... and not "state of the art" about stability.

I think people will belive in LRLs if a REAL and COMPLETE schematic will be posted... and anyone could replicate and check if works or not.

Don't need 30 meters or 5 meters range... also 50cm for a coin could be enough to show people if device works or not... but that needs you post something complete... not pieces.;)

Kind regards,
Max

Hi Max:).
As Esteban wrote it is a circuit from Andy Flind. I have the schematic so Esteban gives me info about the coil. But i like the open loop.

Esteban, if i will not use the radio, at who distance may i locate a big object?? other can you tell me how to connect the radio to the magnetic field detector???

Regards:)

The oscillator and Andy Flind's circuit :) are different things!

Maybe 30 meters... The input reductor in circuit (2K2) you must reduced for better sensibility.

Geo

Also, can be via trafo:

Maybe admins can obtain permission of EPE for to post this:

Hi Esteban.
Thank you.
Some questions yet.
Does The antenna of radio must connected to c1 or must be a wire near the loop???
I suppose that i must use different power supply for radio and MFD.
At who frequency must tune the radio???

My Regards:)

Which was original purpose of this circuit ?

Magnetic anomaly detector ?

Kind regards,
Max