TESORO GOLDEN SABRE

[Mr.Jaick]

Basically the Disc phase shifter op amp has saturation on the input!

yes and i'm wondering how other guys have made this circuit with 16V tx and no problem, it's very strange

[Mr.Jaick]

Hi Mr Jaick.

You have odd waveforms because the Tx voltage is to high for the phase shifter opamps. Listen you have +8 and -6.5~ now thats 14.5 volts powersupply voltage for IC's now you have a Tx that makes 15-16Voltpp and these op maps and comparators arent rail to rail. In order to clear the square waves you have to use for Disc and Geb 14volts at Tx thats enough, and change the Geb 100k resistor with the 15pF capacitor to 47k with 15pF. This way you wont have to much noise in the square waves and Geb signal wont be that distorted triangular it will be a rounded square wave. Oscillator at higher voltages will get distorted sinewave with much noise, use Ivconic's mod and change the 47k resistor at Oscillator to a 100k trimmer and you can make a clear sinewave with that.

hello Nandor
i think you're right , it make sense
my negative rail is -4.8V and positive +8.15V
first i removed all the 100nF bypass caps from supply rails near each IC(i add them on pcb for noise improvement) except of original schematic caps
now the circuit is exactly the original one
it didn't solve the problem.
second
i changed the R3(base of TX transistor) to 100k trimmer pot and result is cleaner wave form
but it didn't solve the problem again.
third
i changed the R23(output of GB channel 100k ) to 47k
still the same problem for the DISC
and a new one , now it can't reject ferrite (it could't before the last change )
so here is the question how to decrease the TX amplitude without distortion?
now we have a disappointed guy who has spent about 4 months and lot of money on this project to make it work, and nothing
btw i've used 22k instead of 24k for R21(LM393 pin 1)

TX signal:

TX vs RX on output of U1, each block is 53 degrees of phase shift(so it's 20 now)

tx vs middle pin of disc pot, disc pot at min

tx vs middle pin of disc pot, disc pot at mid range

tx vs middle pin of disc pot, disc pot at max


something is absolutely wrong

[Nandor]

Basically the Disc phase shifter op amp has saturation on the input!

[Nandor]

Hi Mr Jaick.

You have odd waveforms because the Tx voltage is to high for the phase shifter opamps. Listen you have +8 and -6.5~ now thats 14.5 volts powersupply voltage for IC's now you have a Tx that makes 15-16Voltpp and these op maps and comparators arent rail to rail. In order to clear the square waves you have to use for Disc and Geb 14volts at Tx thats enough, and change the Geb 100k resistor with the 15pF capacitor to 47k with 15pF. This way you wont have to much noise in the square waves and Geb signal wont be that distorted triangular it will be a rounded square wave. Oscillator at higher voltages will get distorted sinewave with much noise, use Ivconic's mod and change the 47k resistor at Oscillator to a 100k trimmer and you can make a clear sinewave with that.

[waltr]

thanks sir i'll check again
after 30% it narrows down again while advancing disc pot, that's the reason for 40% waveform
i've used multilayer ceramic caps for C9 and C10 , should i change it to polyester or MKT type?
and i don't know if it's a genuine chip , perhaps chinese or tiwanian ones
i rarely can find genuine chips around

It is an odd behavior. That why you need to re-check all components. Also recheck the Disc Pot wiring and the pot itself.

I used polyester caps for C9 & C10. So worth trying other caps.

[Mr.Jaick]

The TR4 gate waveform looks good at min. However, the 30% & 40% doesn't seem correct.
Compare to the TGSL 101.pdf.

Then re-check ALL components from C9, R19, through to input of U102.
C9 and C10 are fairly critical caps so ensure you use good quality 100pF caps here.

I also assume you used non-counterfeit chips.

thanks sir i'll check again
after 30% it narrows down again while advancing disc pot, that's the reason for 40% waveform
i've used multilayer ceramic caps for C9 and C10 , should i change it to polyester or MKT type?
and i don't know if it's a genuine chip , perhaps chinese or tiwanian ones
i rarely can find genuine chips around

[waltr]

The TR4 gate waveform looks good at min. However, the 30% & 40% doesn't seem correct.
Compare to the TGSL 101.pdf.

Then re-check ALL components from C9, R19, through to input of U102.
C9 and C10 are fairly critical caps so ensure you use good quality 100pF caps here.

I also assume you used non-counterfeit chips.

[Mr.Jaick]

Hello everybody
i've just sat up my TGSL with 28cm coil
TX: 14.705 Hz and RX: 14.144 Hz
it's fully functional but i think i have some little problem
(1) it doesn't detect above 50 or 60 cm even with a big steel wrench or 1kg of other metals.
(2) it has more depth when i advance the GB pot clockwise more than it needs to reject ferrite.
sample coin(nickel ,copper , zinc or aluminium alloy)
GB set low(less than mid range) = 25cm
GB set high(a bit more than mid range) = 35cm
i'm just worrying about silver rejection...
it doesn't detect copper btw but it doesn't matter to me , just in case to know.
(3) when i switch to disc mode it works perfectly but when i observe the gate of TR4(disc channel) with oscilloscope ,
the waveform disappears after mid range of disc pot(100k)
unfortunately i don't have silver and gold at the time to test if they would get reject when waveform disappears or not...
thank you guys in advance if anyone would help

this is the waveform on gate of TR4:

[kt315]

Qi
we use PRF202 here https://www.lemona.lt/?page=item&i_id=38146

[ivconic]

The best thing to use is PCB lacquer:
https://www.amazon.co.uk/30235-AA-AM...0901123&sr=8-4

Back in 2004/5. on Malta i used something similar.
There was Maplin Electronics shop there and i obtained most of the material at them.
So once i bought something similar.
It is alright. It is doing the job.
But i noticed that it needs bit higher temperature adjusted at soldering iron, to easy solder the parts.
Coating with calafonium is melting and "opening" at lower temperatures.
Maybe is just because of that spray type that i used than. Maybe is not the same case with all.

[Qiaozhi]

The best thing to use is PCB lacquer:

https://www.amazon.co.uk/30235-AA-AMBERSIL-ACRYLIC-CONFORMAL-PROTECTIVE/dp/B017WEOSQI/ref=sr_1_4?keywords=pcb+lacquer&qid=1580901123&sr=8-4

[ionut_mtb]

Later on it preserves pcb surface from any moisture and oxidation.

Agree with you but not this. From what i know, in time, flux residues and cause corrosion on pcb’s. Also not good on precision circuits.

[ivconic]

I owned multicore soldering wire (high quallity) with flux core. did a very good job but is quite expensive. You don?t need extra flux. After i finished this wire i?ve bought from aliexpress sn60pb40 2% flux but i can see that the quality of the soldering is not the same as before. Now i want to order something made in Germany, named alpha fluitin 60sn38pb2cu 3.3% flux as i found 1kg roll at half price. Usually i clean my pcb with isoropilic alcohol.

Indeed they are going crazy lately with hot prices.
This becomes very expensive hobby lately.
I am using what i can obtain at the moment.
Right now i am using these:

[kt315]

What you are referring on is "Kalafonium".
---
no it is not. i bought it for 'probe' and it is kinda from petrol made like semiliquid paraffin.
do not like it because does not dissolve good by alcohol on cleaning. colophony is much better.

[ivconic]

This is how it looks like when coated with kalafonium.
This one is most recent pcb, hanging and drying: