TESORO GOLDEN SABRE

[Max]

is f-frequency?
And w^2 = w*w?

Hi,
yes w^2 = w*w
w = 2*pi*f
f = w/2*pi

f= frequency

The idea is that you put a know cap. value e.g. 47nF or something similar value BUT known and the coil at input of the univ. oscillator.

Then read the frequency of the given by the LC resonant load directly at output of this circuit with your multimeter.

Kind regards,
Max

[Qiaozhi]

is f-frequency?
And w^2 = w*w?

Correct.

[Max]

Hi,
Yes but whats te point if the multimeter have frequency range I can conect it directly/I think/,and if the multimeter haven't frequency range it can't measure frquency?
So, I have to buy multimeter that can measure frequency and then conect to this circuit OR?
WHats the POINT?
Please help friends!!I am noob.And begin to get even more confused!

Hi,
you can just connect your multimeter for reading frequency at the output leads. That's all.

The circuit gives a good buffering and any multimeter will read that signal. I'm sure of that.

You only need a suitable and known capacitor value to use the reverse formula and find the actual inductance of coil.

BFR99 is a special RF transistor... but you can replace if you want with any good dinamic gain PNP one... e.g. a >250 gain 2N2907.
Circuit works too at lower frequencies... but of course you'll never get it oscillate at 400MHz like with the BFR99...

Of course you don't need so hi-frequencies to make your readings... just few KHz are enough for your needs (find inductance value of coils).

Kind regards,
Max

[tiktak]

Use this formula:
L = 1 / (w^2 * C)
where: w = 2*pi*f

is f-frequency?
And w^2 = w*w?

[tiktak]

hi,

Hi,
Yes but whats te point if the multimeter have frequency range I can conect it directly/I think/,and if the multimeter haven't frequency range it can't measure frquency?
So, I have to buy multimeter that can measure frequency and then conect to this circuit OR?
WHats the POINT?
Please help friends!!I am noob.And begin to get even more confused!

[Qiaozhi]

Hi,
Max.
So what is the idea?
What I conect to output points?This circuit measure what?Frequency or inductance?
Because I begin to confuse.
And can this BFR99 be replaced with come more easy to find transistor?
Thanks

This is the oscillator output.
In fact it looks like you can leave out everything to the right of C3, as it's just a buffer circuit.
You simply need to measure the frequency of the output signal, or the output from C3 (if you don't fit FT2) and then use the formula to calculate the inductance (L).

[nelson]

Thanks Max
Ok, yes you are rigth, i was thinking on doing a smaller coil like a 16 cm one. I also have modified a comercial nails finder to run like a pinpointer, wich let me found a 11 mm coin at about 2 cms deep.
About no motion detector, yes, this TGS i think will do the job for getting the targer and for fine detection i ll use my pinponter. Also on my arsenal i m planing to carry my Clone PI MD. For this detector i m bulding a smaller coil to detect the smallest nugget i can. Who knows, if all this work, i ll be more satisfy of my homebrew projects.
One more question i forgot to ask. Changing the frequency by changing the inductance on tx coil, how is the tolerence of frequency range. I mean, if i set up the detector for 14 Khz i know i m on the correct performance, but if for example change the frequency to run it at 20 khz, will performance by reduced or not?

Best regards

Nelson

Hi Nelson,
nice to ear it works good, geb and disc OK. Really nice to see that people here appreciate this little and older tesoro's design like I do... that sometimes also an old design and an homemade detector could give lot of satisfaction.
Cool.
Nelson you're right on nugget hunting detectors: most of them are no-motion !
But there are also motion types e.g. for Tesoro's I would talk about e.g. LOBO... that has motion search mode and no-motion just for pinpointing.

Anyway, you can search for nuggets also with GoldenSabre... and with good results. Often in nuggets detectors smaller coils are used:
4'', 5'', 6'' are examples of that
But I think you'll be fine with a DD22... if you'll search e.g. in river sand...flat surface and if you'll use a separate pinpointer.

No motion mode is used in tesoro's almost for pinpointing (e.g. in BandidoII)... so you just need a separate pinpointer and you could seach for nuggets, motion-mode using disc !

Of course, you can also use just GS... but small nuggets pinpoint is not easy sometimes. I suggest you'll use a separate pinpointer.

In earlier times there were lot of BFO/off-resonance to do the no-motion search for nuggets too.
That's the pitch change you notice in that: beating frequency.
Also some modern PI units used in gold-hunting use the VCO approach that is similar: pitch change.

I think you'll find your nuggets with your GSabre. That's my wish.

Best regards,
Max

[tiktak]

Hi,

Hi,
Max.
So what is the idea?
What I conect to output points?This circuit measure what?Frequency or inductance?
Because I begin to confuse.
And can this BFR99 be replaced with come more easy to find transistor?
Thanks

[Max]

UNIVERSAL OSCILLATOR

Hi,
here we are... ENJOY

I found this circuit some years ago, at local library...it came from an old magazine.

I've built and tested and work great.
Anything you put there, I mean a coil and a cap... and it oscillates !

Can go from BF (1KHz...or less) to about 400MHz. Wide range !

No need of function generator anymore ???

The formula you already have !

but anyway... here it is

frequency=

for lazy people there are also online calculators...like http://www.see.ed.ac.uk/~jwp/radio/s...e/lc-calc.html

Best regards,
Max

[Qiaozhi]

Hi,Look Qiaozhi tell that inductance can be calculated if we now frequency?!?!!?

Use this formula:
L = 1 / (w^2 * C)
where: w = 2*pi*f

[tiktak]

Hi

Hi,
Max.
Thanks.
But isnt it better solution to buy multimeter with frequency measurments and 2V AC range?
Look Qiaozhi tell that inductance can be calculated if we now frequency?!?!!?
This mean that this circuit of your will be very useful for me!!
If you find the proper values for this DD25 coil/it will be 27,8 when finished,so I dont now how to call this/PLEASE post them here I dont wanna waste this housing that I bought.

[Max]

Hi,
Max.
Thanks.I uprishiate that you spend from your time to answer to all my questions.
About the 25DD I am still in frustration.You say ,try use less turns with respect to 28DD,but this 28DD use 120 for TX and 125 for RX!And 22DD use 145 for TX and 151 for RX?If I decrece the number of turns,I should increase the D of the winding?>???
I dont have LC meter!The only thing that I have for now is this multimeter.
Can I measure inductance with this?
The resistance should be from 19,XX to 22,XX ohms!But what should be te inductance?
Here is a stupid picture that I have tryed to show this coil housing dimensions!
That why I think that the former size should be 25cm??
Tomorrow I will have all the materials for making coil,so I am in a hurry!
I have replaced TL062 with TL072 for now,and there seems to be a differance.I have make some tests again with my first coil and looks like its better!Less noise

Hi,
yes sorry. I made a mistake writing previous answer, you have to increase number respect to 28cm and decrease respect to 22cm.

I was thinking at 22cm then wrote 28.

Anyway, you'll get the picture. You need same inductance but you have more area inside your new D shape.

Let me know.

Follow Qiaozhi advice. Buy one inductance meter... there are cheap ones now. Or if you can wait I think I've found a circuit that could solve your problem if you can measure frequency.
Problem is that I'm not at home now... so can't to find the DAMN DVD here!

I'll post it ASAP.

Kind regards,
Max

[tiktak]

hi

porkluvr

[Qiaozhi]

hi,
Qiaozhi.
Sorry excuse my stupidity!

You're excused.
By the way, you should really buy an inductance meter. there is no way to directly measure inductance with a multimeter.
The only other method (without an inductance meter) is to connect your coil to the TX circuit and measure the frequency, either with a oscilloscope or a multimeter with a frequency measurement function. Since you know the capacitance values in the tank circuit and the frequency, you can easily calculate the inductance.

[tiktak]

hi

Hi,
porkluvr.
I have told you that I am begginer and have very little to use and much to learn.
Maybe because of my bad english,but I cant see for shore in which diapazon should I put multimeter when trying to null!
Please look at the picture again 200ma can be measured in DCA!is this correct?
Thanks