TESORO GOLDEN SABRE

[fitos]

Happy birthdays

Happy birthday Ivconic

Fitos

[Max]

I noticed today another thing, and also "solved" huge problem i had latelly.
Usually i am including earphone jack and volume feature on my handmades.
So i noticed at last 7-8 handmades certain degradation on audio and overall behavior, once device packed and finished!? What the hell....!?!?
Today, packing my last TGSL, i checked it before mounting in box; audio was pretty good,smooth,strong enough....and air "depth" very descent.
Once packed in box and EARPHONE PLUG connected in circuity, passing 100 ohms potentiometer for adjusting volume.....swithced ON and...not the same!? Audio was much worse (not smooth but sharp and short), air "depth" much lower??? What happened? Damn!
So after torturing myself and device for a while i discovered that audio MUST go directly to speaker, without any earphone plugs,potentiometers and simillar "parasitic potentials". Why?
In the box, but without earphone plug and pot, connected directly to speaker, audio was excellent...long lasting,smooth,loud etc.etc.
Vice-versa; again ear plug connected - huge degradation of audio!? Same with potentiometer 100 ohms.....(usually i am putting it in serie with speaker)...
Degraded audio has "cracks" at end of detection, depths are poor, audio lasting shorter...
Somehow ...like earplug and pot "sucked" a part of audio signal?
So....i checked earplug - correct and accurate . Replaced with another one, new,...same story!? Same with pot.
From audio output from pcb wire must go shortly and directly to speaker if we want to maintain good audio performances!? Whyyyyyyy!!!?

Finally i do not understand a thing here!?!?!?!?!

Can anybody really understand this? On original Tesoros i presume there must be earplugs? Right?
Ha,ha....hmmmm!
I would like somebody much more conversant to come here and elaborate all this mess!
Actually....audio is ALL here at TGS/TGSL. I think all the performances are coming exaclty from how we gonna solve audio.
I presume it is not conventional audio......and it is not "audio" at all!
It is just sort of negative pulse amplification or something like that.
We have pretty complicated composite signal coming to base on MPSA13.
We have 3 transients from 4024. Those 3 transients are "sucked" by negative LM358 output. Right? When detection occurs, negative LM358 output tends to reach zero. Than base of MPSA13 is polarised enough to start conducting. At the same time 3 transients are "unleashed" for a moment and pass through base, being amplificated by MPSA13 and for a moment we can hear tone in speaker. That is all. Again when no detection, LM358 output returns to negative state and pull again 3 transients from 4024. Base of MPSA13 goes 'high' again and there is no sound in speaker. Right?

That very short moment, when LM358 output tends to zero - most important moment here at TGS/TGSL !!!

At that short and small ammount of signal we do have all the informations we need about detection and detected metal! Most important thing here.

How to take that small ammount of signal in so short time, to "expand it's resolution" and to amplify that sample proportionally???
That is main catch here! I think MPSA13 is not quite able to do the job right.
Last thing i done yesterday is just more amplification and nothing else. Nice,better than MPSA13..but not the ultimate solution, not at all.

Hi,
the use of earplugs and pot could be the cause of lowered / bad audio.

The electrical contacts inside the earplugs are the things to consider better... they can waste energy cause they are not perfect electrical contacts with zero resistance.

The earplug sure modify also impedance matching between speaker and output stage, this is related also to the bad electrical contacts inside.

Usually using headphones the things go better cause both you hear better the small audio variations but also the load of headphones is usually much higher than the earplug one.

In the case of speaker, instead, the few ohms maybe added by earplug contacts and joints could easy interfere with speaker operations... also cause there's much more current involved to drive speaker... and it's reduction will mean just you hear big hot bangs and not just fine movements of the speaker's cone.

The pot is similar issue: even at full conduction one side... there are always some few ohms that make things worse... this is true for all cheap carbon pots...

Kind regards,
Max

[ivconic]

I noticed today another thing, and also "solved" huge problem i had latelly.
Usually i am including earphone jack and volume feature on my handmades.
So i noticed at last 7-8 handmades certain degradation on audio and overall behavior, once device packed and finished!? What the hell....!?!?
Today, packing my last TGSL, i checked it before mounting in box; audio was pretty good,smooth,strong enough....and air "depth" very descent.
Once packed in box and EARPHONE PLUG connected in circuity, passing 100 ohms potentiometer for adjusting volume.....swithced ON and...not the same!? Audio was much worse (not smooth but sharp and short), air "depth" much lower??? What happened? Damn!
So after torturing myself and device for a while i discovered that audio MUST go directly to speaker, without any earphone plugs,potentiometers and simillar "parasitic potentials". Why?
In the box, but without earphone plug and pot, connected directly to speaker, audio was excellent...long lasting,smooth,loud etc.etc.
Vice-versa; again ear plug connected - huge degradation of audio!? Same with potentiometer 100 ohms.....(usually i am putting it in serie with speaker)...
Degraded audio has "cracks" at end of detection, depths are poor, audio lasting shorter...
Somehow ...like earplug and pot "sucked" a part of audio signal?
So....i checked earplug - correct and accurate . Replaced with another one, new,...same story!? Same with pot.
From audio output from pcb wire must go shortly and directly to speaker if we want to maintain good audio performances!? Whyyyyyyy!!!?

Finally i do not understand a thing here!?!?!?!?!

Can anybody really understand this? On original Tesoros i presume there must be earplugs? Right?
Ha,ha....hmmmm!
I would like somebody much more conversant to come here and elaborate all this mess!
Actually....audio is ALL here at TGS/TGSL. I think all the performances are coming exaclty from how we gonna solve audio.
I presume it is not conventional audio......and it is not "audio" at all!
It is just sort of negative pulse amplification or something like that.
We have pretty complicated composite signal coming to base on MPSA13.
We have 3 transients from 4024. Those 3 transients are "sucked" by negative LM358 output. Right? When detection occurs, negative LM358 output tends to reach zero. Than base of MPSA13 is polarised enough to start conducting. At the same time 3 transients are "unleashed" for a moment and pass through base, being amplificated by MPSA13 and for a moment we can hear tone in speaker. That is all. Again when no detection, LM358 output returns to negative state and pull again 3 transients from 4024. Base of MPSA13 goes 'high' again and there is no sound in speaker. Right?

That very short moment, when LM358 output tends to zero - most important moment here at TGS/TGSL !!!

At that short and small ammount of signal we do have all the informations we need about detection and detected metal! Most important thing here.

How to take that small ammount of signal in so short time, to "expand it's resolution" and to amplify that sample proportionally???
That is main catch here! I think MPSA13 is not quite able to do the job right.
Last thing i done yesterday is just more amplification and nothing else. Nice,better than MPSA13..but not the ultimate solution, not at all.

[ivconic]

Hi,
Nice Ivica.
I will try it ASAP.
Did you add a smallpiggy PCB or have changed TGSL1265 PCB?
Can you tell me is there differance between HCF and CD 4024?
In my last TGS I have used HCF.
Also which CD you use?Texas,national or fair?
Thanks

This last? Yes.

I dont pay attention on that. For me 4024 is just 4024 so i am using whatever i find.
Same as with other ic's. I dont mind the manufacturer.

[tiktak]

Hi,

Hi,
Nice Ivica.
I will try it ASAP.
Did you add a smallpiggy PCB or have changed TGSL1265 PCB?
Can you tell me is there differance between HCF and CD 4024?
In my last TGS I have used HCF.
Also which CD you use?Texas,national or fair?
Thanks

[ivconic]

Pay attetnion on last, BD... transistor. Proper choice will give you very smooth and pleasant tone.
For example, i tried BD676 (P-darl) and it gave pretty sharp,short and much stronger tone. I didnt liked it. So changed to BD140 and now tone is very smooth,strong and lasting a bit longer. Exactly what i wanted to achieve.
Of course; speaker is very important also, i tried several types. Yet, ordinary pc speaker (from oldies: 386,486 and P1) will do the job just fine.
Larger the membrane area - much better and richer audio, simply as that.

[ivconic]

CD4024 is just very good option. I would not try to change it with 7660 or any other converter. Main drawback at some Tesoros is just 7660.
CD4024 turns to be much better option.

Refering audio, yesterday i applied this stronger output, it is working much better now. Audio is stong and "soft". Let's me to distinguish correctly about size and distance of detected item.
What is really interesting is power drain!? Just 30mA with loud audio during detection and bairly 20mA without sound!?
Wow!

I suggest you to try this, much better than just MPSA13.

[Max]

Sorry if its stupid question, Im not strong in teoretical electronics, but if negative supply section is causing so much trouble, isnt just better use some DC/DC converter, like:
http://www.tracopower.com/ ?

Hi,
yes is possible, and often other MDs use that strategy... 7660 is a common choice for small negative supply too.

In TGS the voltage converter is in sync with tx operations... but I think a voltage converter could be employed there also with not much troubles.

The real problem is that when I connect my original coil 9x8'' to my first TGS I get more than 14Khz at TX... so still confused about what's in Tesoro's website (12Khz) and schematic we have here... original schematic I mean.

The problem is I could expect 12Khz there using original coil... but get more than 14KHz like with golden sabre plus !

????????????

That's why that stuff is pretty confused at now...

Maybe the schematic we have/had at first wasn't so accurate...

Or, simply is not just TGS.

Kind regards,
Max

Better link:

http://dsb.tracopower.com/PPF/PublisherID/Tracopower/KundenID/Tracopower/VKundenID/Tracopower/S/2/Anbieter/24388/Branche/6956/L2Mnu/0/Level/3/NavigationLevel/0/OrigAnbieter/24388/PM/5/ShowNav/1/ShowSubNav/1/ShowTitle/1/DSB_MAIN_FMS.asp

Sorry if its stupid question, Im not strong in teoretical electronics, but if negative supply section is causing so much trouble, isnt just better use some DC/DC converter, like:
http://www.tracopower.com/ ?

[simonbaker]

Hi,
to deal with 12Khz you need more turns on both TX and RX coils.... say you need 10 turns more... so you'll get about 110turns at TX and then 115 at RX.

But I don't tested that so I'm simply guessing numbers now.

Simon: about the frequency I had thought about using directly the oscillator frequency to do that stuff... but think the absence of a squared signal is a problem ... so I think must be some shmitt trigger there... before injecting the signal at transistors base. The 4024 give that kind of output... well squared signal.

Kind regards,
Max

I agree, need squared signal, means more parts if use oscillator freq, too bad .

Now I'm a little confused about voltage spikes because I found my oscilloscope probe can contribute to spike -- put probe1 on V+ to monitor spikes, touch circuit with probe2 and probe1 shows increased spike! But only true for very small quick spikes I think (hope).

I think the following is useful in general to minimize V+ spike and noise:

1. Move (or add) 220 uF cap to output of LM7808 - reduces ripple from oscillator too.

2. Make R11, R12 in negative supply driver approx .1 X R9, R10 - reduces time TR7, TR8 on simultaneously, less spike.

3. Consider larger R8 to not drive TR6 so hard.

4. Consider larger R7 to not drive CD4024 clock so hard.

CD4024 is weird, can cause crazy spikes depending on connections. Trying to find ways to minimize it.

5. Isolation resistors, decoupling caps on CD4024 and TR7, TR8 driver.

Ok, moving on...

Cheers,

-SB

(still wondering about R40 connection, before or after diode D12..why?)

[Max]

OK lets try with lower frequency.
I made today standard coils (255x137 former) - 106w & 100w @ 0.28
but I can make few coils more more test results.
Suggest new coil data for the same former.
Perhaps 85w-87 will be OK for 12 Khz? And what about Rx coil then, we can't use the same coil as for 14 Khz can we?

Hi,
to deal with 12Khz you need more turns on both TX and RX coils.... say you need 10 turns more... so you'll get about 110turns at TX and then 115 at RX.

But I don't tested that so I'm simply guessing numbers now.

Simon: about the frequency I had thought about using directly the oscillator frequency to do that stuff... but think the absence of a squared signal is a problem ... so I think must be some shmitt trigger there... before injecting the signal at transistors base. The 4024 give that kind of output... well squared signal.

Kind regards,
Max

[simonbaker]

R40 question

R40 is positive feedback on U106b (final LM393).

On older TGSL schematic, it is directly from output of U106b.

On latest schematic (gift pack), it is after diode D12.

Why was it changed and what effect?

Cheers,

-SB

[eclipse]

OK lets try with lower frequency.
I made today standard coils (255x137 former) - 106w & 100w @ 0.28
but I can make few coils more more test results.
Suggest new coil data for the same former.
Perhaps 85w-87 will be OK for 12 Khz? And what about Rx coil then, we can't use the same coil as for 14 Khz can we?

[simonbaker]

Hi,
they are always there... amplitude can change but you cannot totally eliminate: it's a drawback of design.

Kind regards,
Max

Maybe I worry too much about spikes because I saw them in output of LF353 - but now I wonder maybe my LF353 was blown, will check.

Smaller R11, R12 = smaller spikes -- may keep at 470 ohms or a little more and test. I have other ideas to reduce spikes, some diodes and small caps to delay turn-on, turn-off of TR7, TR8 so not on at same time.

Eclipse - I tried some decoupling caps (and isolation resistors) and helps but not as easy as you would think, spikes were very strong. But maybe important, as you say depends on rejection. I think a combination of tricks are worth trying (don't like spikes). Also, maybe C28 is better on output of LM7808 instead of input (or maybe on both).

I want to get finished TGSL because questions of audio, coils, and frequency very interesting for experiments, maybe more improvements possible.

How can coil change audio so much? Very interesting. I hope Ivconic will save two models, one with good audio, one with bad, for comparing. I want to see signal feeding the Darlington in both cases. Good mystery.

Max, I get -7 v or better with no load from negative supply even though I read some people have less -- seems very healthy. If oscillator is slower (12 khz), would bigger caps help (470 uF)? What if we drive it directly from oscillator frequency instead of 1/2 divider?