TESORO GOLDEN SABRE

[ivconic]

Guys a BIG thanks! I am so glad that the TGS is now in operating mode!
The negative voltage is -6.27V, positive is +7.98V, Tx is exactly 10 Volts.
There is sound from the un-adjusted coil , and actually it does detects , constant signal without metal which stops when metal object approaches..
offcourse max distance - 15sm ...heh still adjustments of the coil should be made...
The fight continues whith the coil construction!

Ivonic, congrats on the great machine you got there, I hope it will last long and will adjust many many boards :P!

Thanks!

"...Tx is exactly 10 Volts..."

What do you mean by this? At my TGSL output is 16vPP...

[eclipse]

Uh sorry my mistake. It's 16 Vp-p here also, I'm too excited I suppose
Frequency is far from the real - even with 105 windings coil im at about the same frequency, ~38uS

[Aziz]

Uh sorry my mistake. It's 16 Vp-p here also, I'm too excited I suppose
Frequency is far from the real - even with 105 windings coil im at about the same frequency, ~38uS

Is the 105 windings related to a circle winding core? If the coils are bended to a D form, the inductivity of the coil decreases and thus the operating frequency increases.
Check this out!

Aziz

[eclipse]

Aziz I am following the recepie for the former 255x137 and wire with thickness 0.28 (with varnish).
I don't have LC meter so I can't measure the inductance...
The first tried has 100 windings and no shielding yet, resulting in 35uS mesured on the o-scope = 28,5 Khz
The second tried has 105 widings and shielding ( yes its the Rx coil, which i connected as Tx), resulting in 38uS on the scope = 26.3 Khz
I checked the capacitors in parallel with the Tx, they are fine, they are just like the schematic.
--
The only thing I can think of is that I've been lied in the shop for wires

" Hey boss this guys wants 0.28 wire and we don't have such,
so lets sell him 0.2 wire labeled 0.28 ".

If this is the case i suppose the wire I have is close to 0.28 but less than that, perhaps 0.23-0.25 with the varnish. I don't know how many turns I will have to increase exactly,
I'll try with 121 - 122 for Tx and see how it goes.

[Max]

I am armed now! Sharp and dangerous!

Ha, finally i got some oscilloscope, beer for everybody, on me!

First thing i tested is pin 7. on LF353 ...perfect sinus.
Collector of 2N2907 is giving almost perfect sinus? Right side is a bit distorted...
That was all for now, havent slept from yesterday. Will conitnue tomorrow.

Huh....

Hi,
well done ! I see it well!

Beers now!

On TX side some non linearity is about normal stuff... but not much of it... otherwise there could be troubles.

On rx, pin7 or preamp perfect sinus: yeah, you need that and it happens cause of the resonant tank connected to a fairly high input impedance of preamp... that's why it's so smooth thing.

Kind regards,
Max

[Max]

Aziz I am following the recepie for the former 255x137 and wire with thickness 0.28 (with varnish).
I don't have LC meter so I can't measure the inductance...
The first tried has 100 windings and no shielding yet, resulting in 35uS mesured on the o-scope = 28,5 Khz
The second tried has 105 widings and shielding ( yes its the Rx coil, which i connected as Tx), resulting in 38uS on the scope = 26.3 Khz
I checked the capacitors in parallel with the Tx, they are fine, they are just like the schematic.
--
The only thing I can think of is that I've been lied in the shop for wires

" Hey boss this guys wants 0.28 wire and we don't have such,
so lets sell him 0.2 wire labeled 0.28 ".

If this is the case i suppose the wire I have is close to 0.28 but less than that, perhaps 0.23-0.25 with the varnish. I don't know how many turns I will have to increase exactly,
I'll try with 121 - 122 for Tx and see how it goes.

Hi,
are you sure it's 35uS the whole period of signal ? Cause if so you have about 28.5Khz frequency... about twice the expected of more than 14Khz...

Maybe you made wrong calculations at scope ??? Check that....

I told you... the recipe is correct and really accurate.

If you have also a bad wire... e.g. thinner than 30AWG you'll always get lowered frequency and not higher than the 14-15Khz expected.

Kind regards,
Max

[eclipse]

Hi,
are you sure it's 35uS the whole period of signal ? Cause if so you have about 28.5Khz frequency... about twice the expected of more than 14Khz...

Maybe you made wrong calculations at scope ??? Check that....

I told you... the recipe is correct and really accurate.

If you have also a bad wire... e.g. thinner than 30AWG you'll always get lowered frequency and not higher than the 14-15Khz expected.

Kind regards,
Max

The recepie is bullet proof.
Checked the scope, it was deviding the actual frequency by factor of 2.
Quick recalibration and test, aaa here we are thats more like it - 14.5 Khz.
All misteries solved in one day,
Thank you
I think I need a beer!
Cheers

[simonbaker]

Please tell us what you did to solve each problem - Amplitude, bump, negative supply. We need the sordid details...

Glad it's humming!

-SB

[eclipse]

The "sorded details" :
2N2222 transistor (connected to 4024 trough 1K) was not placed correctly on Ivconics board which I used to make my board. I remember a post saying it's reversed, but when I made the board I forgot to change the orientiation and when soldering I used only silk screen on the board for guideline.
All other transistors are fine (I'm using PN2222 and PN2907)
Signal of pin1 - 4024 after that appeared and this solved the problem with the power supply and the audio appeared.

I also find that I have reversed (again on-board problem) 1N4148 connected to 4V3, because I've changed the pcb design almost anywhere near capacitor so that the Wima caps can fit.
This fixed the problem with the "bump" on the TX and the amplitude.
After calibrating the scope i was able to read correct 16V Tx (which I first though it's 10V) then came up the fact that the freq reading is aslo wrong.
(Okay I want to know who played with the scope ?!..)
We can't do without mistakes could we ?

That's all, the device is audioble, shows signs of detecting metal.
Pin 7 shows square or sinus wave, square when the coils are far from nulled position, sinusoidal signal - when close to ajusted, and the amplitude goes way down when I get closer. It will be hard to null w/o having accurate multimeter, Ill try to borrow better than mine for a few days.
I doubt i can do with the scope with it's 5mV/Div, even if I use it x10 amplificatation, if I use it directly connected to Rx
The only way will be output of LF353, where the signal is stronger.

[Max]

The "sorded details" :
2N2222 transistor (connected to 4024 trough 1K) was not placed correctly on Ivconics board which I used to make my board. I remember a post saying it's reversed, but when I made the board I forgot to change the orientiation and when soldering I used only silk screen on the board for guideline.
All other transistors are fine (I'm using PN2222 and PN2907)
Signal of pin1 - 4024 after that appeared and this solved the problem with the power supply and the audio appeared.

I also find that I have reversed (again on-board problem) 1N4148 connected to 4V3, because I've changed the pcb design almost anywhere near capacitor so that the Wima caps can fit.
This fixed the problem with the "bump" on the TX and the amplitude.
After calibrating the scope i was able to read correct 16V Tx (which I first though it's 10V) then came up the fact that the freq reading is aslo wrong.
(Okay I want to know who played with the scope ?!..)
We can't do without mistakes could we ?

That's all, the device is audioble, shows signs of detecting metal.
Pin 7 shows square or sinus wave, square when the coils are far from nulled position, sinusoidal signal - when close to ajusted, and the amplitude goes way down when I get closer. It will be hard to null w/o having accurate multimeter, Ill try to borrow better than mine for a few days.
I doubt i can do with the scope with it's 5mV/Div, even if I use it x10 amplificatation, if I use it directly connected to Rx
The only way will be output of LF353, where the signal is stronger.

Hi,
that mistakes are very common stuff...no problem.

The square signal is when you saturate preamp... must do nulling to get perfect sinus there...

The 5mV / div are good for most nulling you need... usually there must be some pull switch that multiply sens by factor 10... so getting you 0.5mV / div of sensitivity... but it's not needed in these coils.

Just null at few mV and will work fine... also 10-15mV are good for testing etc.

Kind regards,
Max

[simonbaker]

The "sorded details" :
2N2222 transistor (connected to 4024 trough 1K) was not placed correctly on Ivconics board which I used to make my board. I remember a post saying it's reversed, but when I made the board I forgot to change the orientiation and when soldering I used only silk screen on the board for guideline.
All other transistors are fine (I'm using PN2222 and PN2907)
Signal of pin1 - 4024 after that appeared and this solved the problem with the power supply and the audio appeared.

I also find that I have reversed (again on-board problem) 1N4148 connected to 4V3, because I've changed the pcb design almost anywhere near capacitor so that the Wima caps can fit.
This fixed the problem with the "bump" on the TX and the amplitude.
After calibrating the scope i was able to read correct 16V Tx (which I first though it's 10V) then came up the fact that the freq reading is aslo wrong.
(Okay I want to know who played with the scope ?!..)
We can't do without mistakes could we ?

That's all, the device is audioble, shows signs of detecting metal.
Pin 7 shows square or sinus wave, square when the coils are far from nulled position, sinusoidal signal - when close to ajusted, and the amplitude goes way down when I get closer. It will be hard to null w/o having accurate multimeter, Ill try to borrow better than mine for a few days.
I doubt i can do with the scope with it's 5mV/Div, even if I use it x10 amplificatation, if I use it directly connected to Rx
The only way will be output of LF353, where the signal is stronger.

Nice troubleshooting, you got it going quickly.

I agree with Max, 5mv/Div should be good for nulling -- unless you have some super coil! You will probably see phase shift as it goes through null. According to some, you want nulled signal to have the "200 deg" phase relation with TX signal rather than other side, so scope best for that, hard with multimeter. I'm trying to study this null condition to better understand.

Cheers,

-SB

P.S. Thanks for details!

[eclipse]

Nulled point can easy be spotted with oscilloscope - there
is a place were the signal quickly goes down. At this point - super quick glue.
After that switch to minimum signal range of the scope - 5mV and precise adjust the coil. That's my plan for now ..
I didnt have time to do that today, I think I need new pair of coils.
I noticed that the "sweet spot" require the coils to be more close to each other perhaps with ~1cm.
Is there any difference which coil is up/bellow in the housing or both ways work fine?

[simonbaker]

I am armed now! Sharp and dangerous!

Ha, finally i got some oscilloscope, beer for everybody, on me!

First thing i tested is pin 7. on LF353 ...perfect sinus.
Collector of 2N2907 is giving almost perfect sinus? Right side is a bit distorted...
That was all for now, havent slept from yesterday. Will conitnue tomorrow.

Huh....

You tantalize us with low res picture - but looks like nice scope, can't live without.

So much emi where I live, wish I had like this: http://www.apogeekits.com/oscillosco...ld_hps10se.htm to test out in field.

Cheers,

-SB

[simonbaker]

All metal / ground balance question

With my breadboard circuit, I'm testing discrimination and groundbalance.

Discrimination works nice with non-ferrous metals. It does reduce depth some to nearby metal - e.g. discriminating out pull-tab makes penny signal a little weaker. (maybe better shape square wave at JFet gate would help).

Problem is with iron. It seems that Ground Balance control is used to eliminate iron. But it also eliminates iron for all-metal mode with my circuit. I can't find a place where iron gives beep in all-metal mode but not in discrim mode.

How does it work for your TGSL?

Regards,

-SB

[simonbaker]

Schematic Drawing

Is there a file with the TGSL schematic and software for editing?

Regards,

-SB