TESORO GOLDEN SABRE

[porkluvr]

not the answer

Geo, the FET circuit will fight (and defeat) you when you try to exceed the "design limit". Ten volts is about all I would suggest using. Changing to a 10V supply requires changing the feedback components (use 2N4392?) - or else removing them.

From my experience: a different approach should be used to gain appreciably more power output. Remember, we should operate the phase reference circuits at approximately 50-50 duty cycle.

In my opinion, this particular circuit can not be forced to deliver much more power - or else it will cause unacceptable non-symmetry of the transmitted wave and (especially) the phase reference voltage. How accurate would discrimination be, if it was fed a 55-45 waveform?? I don't enen like to see a 51-49 waveform!! (Well, that's just my problem. Not everybody needs to be a perfectionist.)

I can supply you some of my spice simulation circuits if you would like to experiment with LTspice (it's free). Some people would disagree, but I think it's pretty easy to use. Sometimes, it's almost likeable. It's up to you. Send a pm if interested.

I would like to have a real-life laboratory, but I still live in a shoe where there's not enough room available. temporarily............................... ........... ............. (time keeps marching on, and on, and on.... )

[ivconic]

I have Tina 7 TI installed in my system. Actually i just installed it, few days ago. Still novice in this thing. What do you think? Is it good for a start?
Regards!

[porkluvr]

I have Tina 7 TI installed in my system. Actually i just installed it, few days ago. Still novice in this thing. What do you think? Is it good for a start?
Regards!

I've played with TINA. Much too restrictive. Please, do not waste your time. TI makes good ICs, but their TINA addition is a second rate answer to LTspice. Please believe me.
Download LTspice, and forget about using TINA except for evaluating (ONLY) TI products.
TINA might be better suited for noise analysis than LTspice, but so far as I know, you can only evaluate TI products with the TI version of TINA.
I tried TINA's "evaluation version", several times (years ago, they MAY have changed) and it did absolutely NOTHING for me. (Actually, I may have just been too stupid to get it to work, but that was THEN, and this is NOW.... hmmmmmm. I won't do it again, and again, and, but, I tried several times.)
That was, oh, about 3-5 years ago. TINA may be different now, but... .. Hmmmmm if someone were to ask me what to do.... I would have to say:
I remember that I wasted time trying to get TINA evaluation version to work. I REMEMBER. SWITCHERCAD, on the other hand, was straight-forward from the beginning. Then it morphed into LTspice and it got even better.
So, I recommend:
Download Ltspice.
Run it.
Use it.
You won't be sorry.
You can run TLC2262 with LTspice. So, by the same token: try to run LT1037, or LTC1046, or MC33178 with TINA? (Gag-choke; not allowed, I'll bet)!!! DOES THAT SEEM FAIR ? Damn right it doesn't.

Love those TLC2262, but if you can do without noise analysis, RUN WITH LTSPICE!

[ivconic]

Since i havent started yet to learn how to use it, is not too late to switch on LTSpice ! Thanks a lot Porkluvr! I'll install it and try!

Now, these are simple schematics; milivoltmeter i made and it is working very good. Although scale i do have is low resolution so error can occur. Need high resolution scale to run it just fine. Another, smaller schematic i took from some musician site. It is absolute miracle how this small,tiny preamp working FANTASTIC on guitar pickups!!!!? So those are coils too, arent they? I was thinking to experiment with this preamp a bit more....Seems nice to put it as RX front end...

[Qiaozhi]

I've just fixed the dodgey wiring in the plug of my 10" Tesoro concentric coil. The residual voltage is 4mVpp.

So far I have measured:
9x8 web coil = 13mVpp
Laser 8" concentric = 100mVpp
10" concentric = 4mVpp

All of them work fine on my detector, but the one I prefer is the 9x9 web coil. It gives a crisper sound. Probably because of the 60mm receive coil.

[Max]

I've just fixed the dodgey wiring in the plug of my 10" Tesoro concentric coil. The residual voltage is 4mVpp.

So far I have measured:
9x8 web coil = 13mVpp
Laser 8" concentric = 100mVpp
10" concentric = 4mVpp

All of them work fine on my detector, but the one I prefer is the 9x9 web coil. It gives a crisper sound. Probably because of the 60mm receive coil.

Hi,
yes sound is good but the conic shaped flux that's so cool when you pinpoint targets is also cause of lost of many targets if you don't sweep it at low advancement (5-6cm) ahead each time... too close for my taste... that will require days to scan even a small area.

The good recipe is making a 120+120turns 30AWG DD22 coil... that has more performance and doesn't lack too much about pinpointing...and you don't lose targets at same depth you can find with 9x8''.

If you need a nice coil for coins or other small things... to be used on bandido or other uMax make one... null at max 1mVpp and it will be rock solid and better than 9x8''.

Kind regards,
Max

[Geo]

Why

Hi all.
I am the same with you. I made the GoldenSabre. Of course it don't work. Why........ i don't know, i am very tired to check it. I connected it only as "all metal" mode because i had not the time to connect all the potentiometers and the swiches. So all metal..........one pot for sensitivity and one bridge for the all metal/disc mode and it was ok. But what OK if it dont work. I connected a coil that i had from CL3 and i have a very good oscillation at 15.5Khz. The sine is perfect, the voltages are +8v and -6.2v. When i put an object near the coil i see a variable at the output of LF353 and from LM358 and LM308 but not at the last LM358. The MPSA13 give a continuous tone of 480Hz tone. I take out the last 358 but the MPSA sounds yet. I look with the scope to the colector of the MPSA and i see a sine wave about 10Vp-p. Who is the job of the 220uF capacitor??? why it does not decouple the AF signal?????.
Maybe later or tomorrow to check it again.
Bye

[Max]

Hi all.
I am the same with you. I made the GoldenSabre. Of course it don't work. Why........ i don't know, i am very tired to check it. I connected it only as "all metal" mode because i had not the time to connect all the potentiometers and the swiches. So all metal..........one pot for sensitivity and one bridge for the all metal/disc mode and it was ok. But what OK if it dont work. I connected a coil that i had from CL3 and i have a very good oscillation at 15.5Khz. The sine is perfect, the voltages are +8v and -6.2v. When i put an object near the coil i see a variable at the output of LF353 and from LM358 and LM308 but not at the last LM358. The MPSA13 give a continuous tone of 480Hz tone. I take out the last 358 but the MPSA sounds yet. I look with the scope to the colector of the MPSA and i see a sine wave about 10Vp-p. Who is the job of the 220uF capacitor??? why it does not decouple the AF signal?????.
Maybe later or tomorrow to check it again.
Bye

Hi,
which fets have you used ? BF245 ? if so no problems ... but if you use BF244 or different ones check your pinout cause there are very different from model to model and also from one manifacturer to another.

The fact you ear always the 480HZ tone at output or read it by scope means that maybe the battery checker fet doesn't open (again look at pinout) when capacitor charge.

Check that and let us know.

Kind regards,
Max

[Geo]

Hi Max.
All Fets are BF245C. I hear the 480Hz and i see on scope and i measure it with Freq counter. A lot of instruments for nothing. Now i will go again at the lab to give it again a try. The only that i dont connected right is the 10uF tantalium. I have not it so i connected a 4u7. I think that it is not the problem.
I will write you later, now i go to the Lab (it is down the stairs)
Regards

[porkluvr]

wrong FET

GEO,
Use BF245A, or BF245B. According to spec sheet, the "C" version might not turn off until -7.2V is applied. There is no -7.2 volts in the system, unless you use a different voltage inverter!

Also, could use 2N4393, J107, J113, TIS75, etc.

I think the most critical spec is probably Vgs(off), it should absolutely be no more than whatever the negative rail can supply.

I'm talking about the demodulators. BF245C can work in the transmitter, but I won't say that it will work the way that it was designed.

[Geo]

Tomorrow again.
What i found ????? First of all a problem with coil. I connected it right and now the oscillator works at 14.1khz.The 480Hz signal (10Vp-p) was from false connection of scope, but i hear yet it. Until the input of the last LM358(pin5) the detector works fine at all metal mode. With the scope i have very good sensitivity. But what happened and i haven't sound??? I only hear a low continuous tone and nothing else. I changed the LM358 but nothing. I checked the MPSA13 but nothing. Scope shows a small quad pulse (about 0.5V). It seems that battery check works, but voltages are right.
I dont know until tommorow
Any opinion?????
Regards

[Geo]

GEO,
Use BF245A, or BF245B. According to spec sheet, the "C" version might not turn off until -7.2V is applied. There is no -7.2 volts in the system, unless you use a different voltage inverter!
Also, could use 2N4393, J107, J113, TIS75, etc.
I think the most critical spec is probably Vgs(off), it should absolutely be no more than whatever the negative rail can supply.
I'm talking about the demodulators. BF245C can work in the transmitter, but I won't say that it will work the way that it was designed.

Hi porkluvr
Fets seem to work fine. But when i will finish the detector i will give a try with 245B. But now i have other problems.
Anyway thanks
Regards

[ivconic]

Did you put compensation on LM308H ? Very important! If you omit those capacitors; either it will not produce audio either it wiil scream as you described. Or maybe you put bad caps there? Also it will scream if you turned LM308H wrong way, pin1. under notch?Like i did! But we already established that? Pin 8. is under notch! Remember!
It has something to do with LM308 or arround those...Check all over again...
Also you might be turned fets reverse? Check again cose i noticed wrong designating on some schematics here...
Holding thumbs for you Geo!

[Geo]

Hi Ivconic.
At the out of LM308 i have good signal (with a coin at 25cm), the same at the out of LM393 and the input of the last LM358. From here begin the problem.For me the problem is around the LM358.... MPSA13 and maybe the BF245C for the battery check, When i will return from work i"ll check or replace it. Finally if i don't find the problem i will connect the pcb with 4N35....555 Lm386 and will be OK.
Who is the difference at sensitivity between "all metal" and discrimination"
Regards

[Geo]

I think that i found the problem. As i saw at the datasheet for MPSA13 and BC517 there is a mistake at the pcb aboyt the position of MPSA13.The position is right for BC517 but not for MPSA13. I must reverse 180 degrees the mpsa13 to work. What to say. Ivconic or Max what transistor do you use..... mpsa or bc?
When i will go home i will try it