DIY TGSL STEP BY STEP BUILDING AND TESTING

[Ozoz_xba]

I have make a coil and tx i have arranged it to 14.6khz ...but i cant arrange the rx...as i trying to arrange the 16.1khz but after nulling the s8gnal is not so good to get the frekuency.....should i arrange rx frequenxy before nulling ,tx and rx in board away from each other?1 have 1 chanel scope only... another question the discriminate 100k pot is for sensivity arrangment or not????
Any reply will be helpfull thx

[Ozoz_xba]

My coils also is 13.7 cm one of them, both it makes 23-24cm ,maybe maybe should i make my coils at last both 35cm to get deph at 35 cm 1 coin?
Also 1 coil should be 6.2mH?or 8 or 9mH for 35 cm both coils?

[Ozoz_xba]

I cant measure the 14.5khz frequency on tx.it was 17.8khz and after calculation i need about 7nf more in to get 14.5khz frekuency .i put an 6nf parallel to 22nf but frequency gone just 16.8khz or something like that...what to do to change it any help please...on lrc metter my tx is 6.180 mH ....(after putting the capacitance pallalel and trying to nulling rx ,the rx not on board looks like had 0.9vac it was not more millivolts)was that normal?

[Ozoz_xba]

I put now the coil tx and rx my frequency in tx is 17.8khz and rx 17.4khz....the tx signal is not prefect maybe as i see from scope... is the tx and rx khz normal or should i take some wire from tx?in previous i put tx and rx ib mHenry.
At this frequency i get max (after max nulling arranging GB)1 coin at all mode 20cm 16cm prefect noise..what to do ... is possible to get 1 coin from 30 cm at good noise in all mode?

https://ibb.co/HY12h7G

https://ibb.co/fSSN7dv

[Ozoz_xba]

you have to know if you put a copper into a coil then the inductivity of coil will decrease. its famous effect much people do not
understand (whole their school time was wasted on the girls) and do not want understand. so if you will measure a coil you get wrong data.
we have the table with data of manufactured coils but all that is MEASURED DATA, NOT REAL.
if you see '5.5mH' there you have to do 6mH.
it is simple rule you have to follow for VLF coil.

also, if you put ferrite core inside a coil you will get INCREASING of inductivity, you see - THAT IS MIRROR EFFECT to above with copper.

I have now a new 2 coils and hope that them work..tx is about 6.180mH and rx is 6.5mH

https://ibb.co/qJ1r5qJ

https://ibb.co/cbMqHLw

By the way if i put a copper inside a tx if the signal on scope dont change?

[kt315]

you have to know if you put a copper into a coil then the inductivity of coil will decrease. its famous effect much people do not
understand (whole their school time was wasted on the girls) and do not want understand. so if you will measure a coil you get wrong data.
we have the table with data of manufactured coils but all that is MEASURED DATA, NOT REAL.
if you see '5.5mH' there you have to do 6mH.
it is simple rule you have to follow for VLF coil.

also, if you put ferrite core inside a coil you will get INCREASING of inductivity, you see - THAT IS MIRROR EFFECT to above with copper.

[Ozoz_xba]

As kt315 wrote, just make rx with around 6.2mH. I used coils with 5.5 and 6.1-6.2 and they perform very the same way like 5.9 and 6.5... and this is why i nearly never count turns, depend highly on dimensions and tightenning of coil windings, so I rather check inductance and their ratio, thats the headline.
Regarfing transiator - is possible that it was in correct position before? 2n2222 are in different pinouts. Did you used tester or how you figured that it was turned?

I checked the pins and found the pins base collector emmiter,i must say that both j107 was place in wrong place(drain source,gate.) I will make tx 6.2mh and rx 6.5mh..before my 2n2907 of the oscillator was put in wrong pins. I checked and changed the pins after the oscillator circuit worked.before changing the pins of 2n2907 the oscillator circuit was not running...

[Hyena]

As kt315 wrote, just make rx with around 6.2mH. I used coils with 5.5 and 6.1-6.2 and they perform very the same way like 5.9 and 6.5... and this is why i nearly never count turns, depend highly on dimensions and tightenning of coil windings, so I rather check inductance and their ratio, thats the headline.
Regarfing transiator - is possible that it was in correct position before? 2n2222 are in different pinouts. Did you used tester or how you figured that it was turned?

[Ozoz_xba]

you would have to get 6-6.2 mH. then you input in 12.5-14kHz needed.

I will make another 2 coil tomortow then looking for mH at least tx 6mH and rx 6.5mH,it looks like for tx 6mH will have at last 110 winding at 0.25 mm wire and for rx at last 120 winding not just like in project 97winding tx and 107 winding rx...

[kt315]

you would have to get 6-6.2 mH. then you input in 12.5-14kHz needed.

[Ozoz_xba]

It is 220nf and 22nf on board..the coil tx is about 17ohm 5.5mH ..yes it looks like 3mH and the frequency is about 20.9khz on tx.with 22nf and 5.5mH coil i should have 14.5khz on coil but its 20.9 .. i will jump to 33nf i see ig frequency changed tomorrow

https://ibb.co/f27BDNW

before it was 14.6 khz i saw that but some bjt 2n2222 was incorrect pin installled in board and i corrrect it,after it jumps to 20.9khz

[Hyena]

if you have 220nF and 22nF just encrease to 330nF and 33nF. do not measure nothing. the result will show you right way
and write what freq you got.

If I was right, he will have 16,8kHz. To get closer he would use 470 and 47nF to get 14,06 kHz. It wont work well anyway... He need to measure inductance of both coils at first.

[kt315]

if you have 220nF and 22nF just encrease to 330nF and 33nF. do not measure nothing. the result will show you right way
and write what freq you got.

[Hyena]

My circuit works now.. it regornize the metal 1 coin in all metal mode about 15cm .on the scope my frequency on tx is 21khz...should i make another coil or how should i arrange the frequency on tx on board to get 1 couin from 25-30 cm

It does not matter only on Tx frequency. Its about resonant frequency of Tx and Rx. You need to measuere inductance of your Tx coil and Rx coil. If you used 220nF and 22nF capacitors in oscilator AND you measure 21kHz, I susspect that your coil have only 3mH. See? Without known inductance you can not even set your frontend. Do not change caps, just measure them precisely. Dou you have exact 220nF and 22nF? Frequency is 21.000kHz? And measure your inductance or we can calculate it roughly from these numbers if you willl measure them precisely. After correct frontend you can continue to your 30cm journey...

[kt315]

increase caps value in tx generator before you get needed 14kHz.