TESORO GOLDEN SABRE

[tiktak]

Sorry for boring questions but you mean this 358 and this transistor?

[Max]

Also 5.7 volts on +V rail is low... ? you would have 8volts !

One moment... 2x9volt batteries parallel ???

You are using too low voltage....

You give 9volts to circuit but lm7808 have a DROPOUT of about 3volts... that's not good! You need at least 12volt source...
could use 8AA cells.

Have you measured current drawn by circuit ?

Best regards,
Max

[Max]

The + is around 5.7V I use two paralel 9v batteries!
How to measure the negativ rail?I have here only cheep multimeter like on one of the ivconics picture of making DD coil!
I have made DD 28cm with 0,30mm 115 TX ; 127 RX
But when I remouve this LM58 I should cut batt check right?And the md should work?
Thanks

Hi,
no when remove last lm358 you lose also U107a that serves to drive output stage so your detector can't work.
I ask you do that to insulate fault... then you have to reconnect it.

Measure negative rail putting your multimeter's +lead to gnd and -lead to -V rail.

Best regards,
Max

[tiktak]

The + is around 5.7V I use two paralel 9v batteries!
How to measure the negativ rail?I have here only cheep multimeter like on one of the ivconics picture of making DD coil!
I have made DD 28cm with 0,30mm 115 TX ; 127 RX
But when I remouve this LM58 I should cut batt check right?And the md should work?
Thanks

[nelson]

Hi Max, yes i think this is the hardest part of the project.
Anyway i ll keep traing until i get good results.
Yes i agree in this case that inuctance is not to important. I just discover that if you made the coil to match impedance btw 19 and 22 ohms, you are geting closer and then if you mesure inductance you get the correct values (21.6 ohms and 5.9 mH for TX coil). Now why this detector must mach 19 to 22 ohms of resistance?
Has a hamradio hobbist, i learn that most of radiotransivers use 50 ohms of impedance, so antenns must match this impedance. Is the principle of adjusting coils the same has used for antennas.
Thanks Max and friends.
Best regards
Nelson

Hi Nelson,
you are doing a good work on your coils. Let me say that I think you'll gain great experience and skills making your coils. Same thing happened to me.
As ivconic stated many times... inductance matching is not so important if you know what are you doing... just you need to match the tx operating frequency as expected (but also this point you could even change, then making minor changes e.g. on some caps in the circuit) and get a good nulling on rx. Both tx, rx matching expected resistance values within 10% tollerance.
And all your coils will rock.
To answer your question:
I always noticed that adding shield increase inductance. Adding foil you get a increase of inductance, of course. Also with aluminium/mylar I use is the same... but I get less added inductance that way (al film is really thin).
You have to remember leaving always the gap in the shield and have two different (insulated) shields for both coils. Then just use two bare wires to connect to gnd point at cable inside the coil housing. Remember, do not create closed electrical paths between the two shields, this would affect performance, so insulate each other using e.g. tape or paper.
Another trick to avoid too capacitive or inductive added effects is to space the shield from the wound. It's described on BBSailor article on fast monocoil for PI, but principle is always good if you need less cap. or ind. disturbance on shielded coils. Use polyethilene spirals for this... but in VLF just you don't need that stuff I think. I never used in VLF, but only PI coils.

Best regards,
Max

[Max]

When I have removed this LM358 no sound at all and also not working?
What shell I try next?

Hi,
-Remove TR10, reconnect U107 (lm358 )... test.
-Then also measure voltages +V and -V and report.

Best regards,
Max

[tiktak]

hi

When I have removed this LM358 no sound at all and also not working?
What shell I try next?

[Max]

Then how?
And in what kind of troubles?Have I burned anything allready?
Please corect this picture!?!?
Thanks

Hi,
No need of correction! Picture is ok... just make that insulation between foil of the two shields. Then make as in the picture.

You can't burn anything that way... touching shields... but maybe you have done a mistake on circuit assembly.

Don't know... try the test I suggested and report results.

Best regards,
Max

[Max]

sorry forget to upload

Hi,
yes it is like I have done on mine.

In the circled area, where shields overlaps, put some tape or other insulant media... to prevent making a connection between shields there.
Only connection by wires as in drawing.

Best regards,
Max

[tiktak]

Hi

Then how?
And in what kind of troubles?Have I burned anything allready?
Please corect this picture!?!?
Thanks

[tiktak]

sorry forget to upload

sorry forget to upload

[Max]

I conect like this!
Did you leave the two windings to tuch each other in circled areas?
Thanks

Hi,
touch ??? you mean shields ??? NO.
Shields must be insulated each to the other... only connection you need is by shield wires ONLY. If you create a closed path between shields you get into troubles...

Best regards,
Max

[Max]

Thanks MAX,
But it dont stop??!!
Why?
What could be the reason?
Then how you conect?
I mean I conect for TX start of the TX winding and the other from the point where I have put together both coil ends and both shields!And for TX the start of the RX winding and again the point where the two shields and both windings ends meet!

Hi,
if sound doesn't stop in disc mode after 3-4 second you have some circuit problem.

- Check voltages at +V and -V rails... check components and connections around battery checker...

- take out of socket last lm358 (in ivconic mod schema is labeled U107)... still sound ???

- disconnect TR10, and keep connected U107 , still sound ???

Let me know,
Max

[tiktak]

Hi

I conect like this!
Did you leave the two windings to tuch each other in circled areas?
Thanks

[tiktak]

hi

Thanks MAX,
But it dont stop??!!
Why?
What could be the reason?
Then how you conect?
I mean I conect for TX start of the TX winding and the other from the point where I have put together both coil ends and both shields!And for TX the start of the RX winding and again the point where the two shields and both windings ends meet!