TESORO GOLDEN SABRE

[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

[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

[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

[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).

[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!

[tiktak]

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

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

[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

[Qiaozhi]

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

Correct.

[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

[tiktak]

Hi,

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

Hi,
Max.
You mean that I can conect this simple multimeter that I have to this circuit and I will be able to measure frequency?But in which range should I put my multimeter?
Thanks

[Max]

Hi,
Max.
You mean that I can conect this simple multimeter that I have to this circuit and I will be able to measure frequency?But in which range should I put my multimeter?
Thanks

Hi,
your multimeter must have the frequency meter built in.

Or you have to use scope or a stand-alone frequency meter.

Best regards,
Max

[tiktak]

Hi

Hi,
Max.Its look like I have to buy one FAST/multimeter with frequency reading/!!!!
But if I have one why I need this circuit that you have shown?
Whats the idea?More precize reading?Or?
And one more question:the BFR99 have 4 legs and 2N2907 have 3?
What should I conect to this S point which goes to ground?

[Qiaozhi]

Hi,
Max.
You mean that I can conect this simple multimeter that I have to this circuit and I will be able to measure frequency?But in which range should I put my multimeter?
Thanks

Here's an example of a multimeter with a frequency input ->
http://www.maplin.co.uk/Module.aspx?...meter&doy=19m8
It also has the advantage of a capacitance meter, so that you can measure the capacitor accurately.
Preferably you should buy this -> http://www.peakelec.co.uk/acatalog/jz_lcr40.html

[Qiaozhi]

Hi,
Max.Its look like I have to buy one FAST/multimeter with frequency reading/!!!!
But if I have one why I need this circuit that you have shown?
Whats the idea?More precize reading?Or?
And one more question:the BFR99 have 4 legs and 2N2907 have 3?
What should I conect to this S point which goes to ground?

The reason for the circuit?
Answer (with a question): How are you going to measure the frequency if you don't have an oscillator?

[Max]

Hi,
Max.Its look like I have to buy one FAST/multimeter with frequency reading/!!!!
But if I have one why I need this circuit that you have shown?
Whats the idea?More precize reading?Or?
And one more question:the BFR99 have 4 legs and 2N2907 have 3?
What should I conect to this S point which goes to ground?

Hi,
fact is that is simple using the formula of above , so just one capacitor, instead of using e.g. the tx section of GSabre directly then reversing the Colpitts formula to get inductance. But you can do also that way... you haven't buffer but you can read frequency directly from GSabre oscillator too.

Circuit is a general purpose one... could be used for other measures of frequency on general LC loads.

You need in both cases a frequency meter, or a multimeter with it built-in.

I was thinking you got one already (multimeter)... so I posted the oscillator circuit.

I know. So could be worth getting a good multimeter with inductance meter too ... like suggested before... than find a new with just frequency meter!

Anyway, when I talk of "built in" freq. meter I mean a multimeter like the one below (must be Hz label somewhere at rotating switch).

About the S = shield , is the metal case of BFR99, internally connected to the S-lead. You could also ignore it if use e.g. 2n2907.

Best regards,
Max