TESORO GOLDEN SABRE

[Ultimate_Haze]

Hi,
Ivconic.
Thanks for the fast reply!
So TX is ok.
I am shame but its my first steps with oscilloscope and still ALOT to learn.Plus I dont have manual for this.So how to understand what is my p-p voltage?
On second picture there is TX signal/collector 2907/ VS 353 pin7 this is in chop.Anyway I will make some more pictures.
But still my sensitivity is too low.
I have noticed before that there is a small diferance in voltages somewhere in RX section.I will check again and will give some more info.
Have a great day.

[ivconic]

Oh yes; take measuring from pin 7. of LF353 and post photo here...

[ivconic]

I think there is nothing wrong with your TX signal. I get exactly the same shape. That little notch is supposed to be there.
Is that 15vpp amplitude? I think it is. So you have very right signal at TX output. Good!
Cheers!

[Ultimate_Haze]

Hi,
Max.
I have try to adjust like you show.But I can see this relationship only in chop.Is this normal or my oscilloscope is not working properly?
I see that my TX signal have some distortion in peak.Can this be the source of my problems?
Here are some pictures:

[simonbaker]

audio stage

Hi Ivconic -

Referring to your "TGSL Final" schematic audio amplifier section:

1. Did you try using an MPSA13 or other Darlington in place of the two BC547 transistors? Or is there a good reason to have the two BC547?

2. Why is emitter of TR3 (BD140) connected to +V, instead of collector? The circuit seems very unusual, how did you decide on it?

Regards,

-SB

[simonbaker]

It's not needed really... cause if someone wanna a battery checker can do much better using e.g. a led that glows when battery low etc

It's just a power drain... better avoid it, I don't like original design about it.

Sometimes is better pulling out fets...

Kind regards,
Max

Hi Max:

But I am asking about u107b which is there anyway, so shouldn't we put minimal connections to stop noise, oscillations, etc?

Regards,

-SB

[Max]

Hi Ivconic, Max, and all:

My question is about U107b (half of LM358 for unused battery check).

Ivconic said to make connections as in schematic -- I think maybe to stop random oscillations or noise?

Do we really need all those resistors, or is there a simpler way to "deactivate" U107b, also with least amount of current drain?

What would be simplest, lowest power connections needed?

Regards

-SB

It's not needed really... cause if someone wanna a battery checker can do much better using e.g. a led that glows when battery low etc

It's just a power drain... better avoid it, I don't like original design about it.

Sometimes is better pulling out fets...

Kind regards,
Max

[simonbaker]

Hi Ivconic, Max, and all:

My question is about U107b (half of LM358 for unused battery check).

Ivconic said to make connections as in schematic -- I think maybe to stop random oscillations or noise?

Do we really need all those resistors, or is there a simpler way to "deactivate" U107b, also with least amount of current drain?

What would be simplest, lowest power connections needed?

Regards

-SB

A link I found about it:

http://www.maxim-ic.com/appnotes.cfm/an_pk/1957

Most TGSL schematics seem to have the u107b output driven low, which the above article says would consume extra power if it goes all way to rail.


-SB

[simonbaker]

Unused 107b

Hi Ivconic, Max, and all:

My question is about U107b (half of LM358 for unused battery check).

Ivconic said to make connections as in schematic -- I think maybe to stop random oscillations or noise?

Do we really need all those resistors, or is there a simpler way to "deactivate" U107b, also with least amount of current drain?

What would be simplest, lowest power connections needed?

Regards

-SB

[ivconic]

No...i do not suggest you that. Do more experiments on coil. Try to improve it.

[metaldetector107]

last TGSL

Dear Ivco
thanks so much, i have reduced coil inductance from 6.5mh to 6.2mh for RX and from 6mh to 5.8 for TX onw detection depth is better it is around 25cm for single 1.7cm silver coin..
monostable? do you mean Max mono the one with 555 trimer if yes
should i disconnect the main audio amplifier to connect monostable?

many many thanks

[ivconic]

Yes it is true. But that result was with monostabile mod included. Without monostabile mod , best you can expect with 27cm DD coil should be 1e coin at 30cm up to 34cm in air (Disc on "3", Sense at "10") very stabille , no falses, cable from coil to detector can be moved, touched, punched - not even one false signal.
I made over 30 coils so far. Let's say only 5-6 of those were so good to detect 1e at 34-36cm in explained conditions. Rest of coils were pretty solid in performances and usually do detect 1e coin at 30-31cm in air in same conditions.
If you are interested how TGSL works with monostabile mod than watch this video:

http://www.youtube.com/watch?v=CxUOcCQBqU4

This specific coil detected 1e coin at 41cm in air. A bit larger silver coin (2cm) detected at 48cm in air.
But....there is always some catch! Monostabile mod is not working very good on soil - tends to produce ocassional false signals, so i do not recommend it to you...at least not for now.

Al shaft ...bar.. ok, of course you may use. Leave 20cm plastic bar from coil and than use Al pipe to detector...As on any other original model.

[metaldetector107]

last TGSL

Dear Ivco
please u said your last tgsl will detect 1coin at 46cm in air if coil proper nulled can i get this resault if i try ????
may i use alaminum shaft because its light and stiff?

thanks

[ivconic]

You better do that. Apply shield on both coils.
2.4cm coin on 20cm is not such good result. 2.4cm coin it must detect least at 30cm, if not a bit more. But this is not cose of a shield. Either coils are not balanced properly, either you missmached wire gauge, coil dimensions or number of windings. Involve some effort and try to make good coil, shielded also.
Regards

[metaldetector107]

last TGSL

Dear Ivco
thanks for all your help i realy appriciate.
i have tested without shielding coils
i can reject most types of iron the black thingy ferrite 7cm long 1cm dia
only i hear carck 2.4cm coin at around 20cm
so do i need to shield the coil ???
thanks in advance