lobo improved

[tchoci]

Hi,

[tchoci]

Hi,FOMA
coil-Tx=65/0,28 Rx=170/0,22 D=22sm.

[FOMA]

HI TCHOCI.

The Good results.
What amount whorl TX and RX?
What sizes of the sensor?
If possible photo.

[tchoci]

LOBO the best. 50 €cent -32sm. for air.Discriminate-OK,F=17kHz,Vpp/gen.-14v.Ground-OK
Q1-2T914A;U1-HA17555;U4,U7-NE5532;U10,U11-OP177;Ctx-44nf;Crx-1,3nf;U8,U9,U14-LM158;U13-TL072

[maxbiri]

Hi Porkluvr

I check Foma's schematic and see yours corrections.
I think that tx tank capacitor must be 47 nf and not 4.7 nf, Foma use 1.33mH tx and not 10 mH!
I presume that my first idea using 10 mH as RX and not Tx is correct.
Solved the problem around 4024 now citcuit is more stable and i gain 2 cm in deep but again i think that 20-22 cm in air is not a good result for a 50 €cent.
I test even a omega coil style coil, Magnum type, and after mach tank capacitors it work, more or less,in the same way as DD.
If you need same photo about signal in lobo let me know and i will do.

Bye Max

[maxbiri]

Hi All

It was 4024!

I check again all, no error, shortcircuit and pcb was washed for removing fluxant.
I cut trace from pin 3 of 7555 and pin 1 4024 and magicaly i have good square wave form and stable F on pin7.
I desoldered 4024, it was the only ic directly soldered on pcb!, i forget first Murphy's law , put a socket and change 4024 with one from ST, now all seem OK.
Now i can restart test.

Bye Max

[porkluvr]

It seem that 20 khz signal is modulate at 10 khz.
Tested oscope, it's ok.
Thinking that problem coming from 7660, that work at 10 khz half F generate from 7555, i remove it but nothing change!
Next step is: remove 4024 and woodo rite!!!
first photo is on 7555's pin 3, second on pin 7.

Bye max

Recalling my days when I used to push an oscilloscope probe for a living (back when I had a job); that looks to me like you may have a short circuit between two signals. Measure ohms between 4024-1 and 4024-12. Should be megohms resistance between. A kilohms reading may indicate a bad 4024. A low ohms reading could be a solder bridge.

Before you remove anything else, poke around with your scope probe until you see another point on your PCB that exhibits the same waveform. If you find it, that will be a clue!

Hallo Cordius & Maxbiri.

Think you both are speaking the same language.....?

[cordius]

HI,
I read only the last post, check well and make sure that C60 and C63 capacitors near ICL7660 have positive pin on ground.
Excuse my english.

[maxbiri]

Hi All

I presume that little distorsions are not important but strong distorsions like that in photo give big problems at comparator output, you havent a sigle square pulse but a little serie of fast square pulse that can afct ground cmpesation and disc.
I take same other pictures from o scope, very strange thing happen around 7555!
I change all components aruond 7555, and different 555 type, and put a ceramic multilayer 100 nF capacitor on pin 5 and ground.
Noise at pin 5 is less than 1 mv.
It seem that 20 khz signal is modulate at 10 khz.
Tested oscope, it's ok.
Thinking that problem coming from 7660, that work at 10 khz half F generate from 7555, i remove it but nothing change!
Next step is: remove 4024 and woodo rite!!!
first photo is on 7555's pin 3, second on pin 7.

Bye max

[aft_72005]

Hi maxbiri
See pictures, from my golden sabre light , osc out put having distortion ,
I did try to better it with some changes in automatic level control section ,
Contain Fet and zener diode . anyway, I dident important reaction at tgsl
Work.
Best regards.

[porkluvr]

I need a break from trying to hack Pspice models from OrCAD into LTspice. grrrrr. Usually pretty easy, but tonight the LM385-2.5 / LM385-1.2 are driving me crazy. Foundation work makes me tired. And it seems to be never-ending.

Not meaning to step on anyone's toes - but I disagree about signal distortion. Maybe on TGSL it doesn't matter so much, but this is not TGSL. Don't assume anything until you have a product that makes you happy, and then you can start testing fudge factors.

The TGSL has no adjustment comparable to the amplitude adjustment on the LOBO, and you don't know how much distortion is acceptable. Power vs discrimination accuracy is what you are trading. You might not gain very much transmitted power compared to the amont of distortion in the phase reference !!! (Looking at Fisher detectors, it seems to me that they take phase reference 50/50 waveforms VERY seriously!)

Waveform distortion on the TGSL (using a Colpitts oscillator) cannot be eliminated, but Tesoro DID attempt to minimize it with the FET amplitude stabilizer. And, it is possible that Tesoro's reason for using the LOBO scheme was -total- (well, almost) elimination of a distorted signal going to the ZCD comparators. Just a thought.

What really bothers me is your saying that the 7555 output is not uniform. I suggest you try another one, maybe that one is defective? Or, check the RC components first. That seems like serious issue. God forbid it's a problem within your o'scope!

[simonbaker]

Hi all

In these days i'm tryng to calibrate oscope and built a simple L-meter for testing coils.
I found that 7555 generate a square signal not costant, i put a 100nf capacitor from ground and pin 5 but not solved the problem.
Now i post 2 sample photo take from oscope, this is the best i can do, sorry graticula is not visibile.
First one is signal on tx coil 10 vPP, good sinusoidal, if i increase power driver on tr base signal began distorted on top side, second photo.

Bye Max

Distorted signal looks similar to TGS oscillator when the feedback JFet is removed -- But Ivconic says doesn't matter in his tests. Is air depth affected?

-SB

[maxbiri]

Hi all

In these days i'm tryng to calibrate oscope and built a simple L-meter for testing coils.
I found that 7555 generate a square signal not costant, i put a 100nf capacitor from ground and pin 5 but not solved the problem.
Now i post 2 sample photo take from oscope, this is the best i can do, sorry graticula is not visibile.
First one is signal on tx coil 10 vPP, good sinusoidal, if i increase power driver on tr base signal began distorted on top side, second photo.

Bye Max

[porkluvr]

Seem that change from 5 to 12 volt have not good result; i found this very strange but need more test.
Bye Max

Max.
I think I have seen four different Lobo schematics, and wonder if some of them aren't rehashes of previous drawings - perhaps perpetuating any earlier mistakes? How many are actually based on tear-downs? And, I have seen not even one oscillograph of Lobo waveforms. To see some good dual trace shots of the GCX, DISC and received signals would be MOST helpful. I suppose having them well labled and explained, would be out of the question.

I have not really studied the schematic that I provided, only glanced it over. There may be errors. Don't believe everything you hear, (and only half of what you see)!

Your 40 ma with 12V sort of doesn't make sense - but stranger things have happened. (But maybe you meant 4ma?) Does that include the 555 current?
A while back as I experimented (in my virtual lab) I had a "good" setup with 8V supply. But always wanting more - I applied 10V and tried to dial in the circuit. Not good. I forget exactly what it looked like but had high distortion. Could not get more usable output than with 8V! I gave up on that 10V project. Maybe you should keep that mind as you try to use 12V!

I did bump up the frequency to 30kc or so, and, surprisingly, got it to look good with 10V power supply! Decided against trying to prototype at 30kc; thought it best to learn with ~20kc. I am again working with 10V, but as stated previously, hacking the Golden Sabre " Colpitts" oscillator. It seems to be fairly managable at ~21.5kc with 10V supply.

I'm curious, what frequency are you pumping?? Also, where are you measuring current to TX? Masuring current is very easy to do in spice, not so easy in real life. Did you measure voltage across emitter resistor? (I=E/R)

With 5V supply, your 9Vp-p seems pretty good. In my spice lab I could get 10Vp-p, but that is not real life. Various unknowns are at play.

Any oscilloscope pics you can post would be good. If you have problems you may be able to get assistance from one of the engineers or service technicians reading this.

I have a "toe hold", but still, many questions about how and why Tesoro IBs function. Good oscillographs with explanations are hard to find. Ivconic's "Golden Sabre Light" thread has yielded good information. At the risk of getting trapped into thinking in generalities, I have based my perception of the Lobo upon information available about other Tesoro models (such as GS, various Silver Sabre models, Eldorado, and Bandito). Sometimes it's hard to seperate facts from BS, but until I have an actual test bench and room to work - LTspice and what I have read are all I have to go on.

Bye