TESORO GOLDEN SABRE

[nelson]

Hi Ivconic.
Today i finish tesoro golden sabre pcb with all components on it.
Just need to know how to connect swithches and potenciometers. can you draw it on the pcb to get a clearly idea?.
For 4.7uF caps i took two 10 uF electrolitics caps and solder the negative lead to each other. Then i place the positive leads on the board, but the value measure with my L/C meter II B, show 2 uF. Is this a problem?
For coil i ll make the same that you post.
Regards
Nelson

Here are pictures of my MD

Took another look at it, and...YES! KT315 is right! I traced pcb again.
Yes KT315 you are right! How i missed that!!!??? I have few different
schematics here....I payed attention on wrong one...Shhheeeeeesh!!!
Bravo KT315 and thank you!
But about loading resistor you mentioned...? I am not sure? Yes i can agree
with you, there must be loading resistor...but it is not there? And device is
working excellent!?
I corrected schematic and here is now; i really hope complete and accurate!
Porkluvr....Yes double O coil showed best results so far...but i gave up of those!
Why? I am gonna explain why; not so suitable on terrains i've been visitng lately.
There are a lot of bush arround,tree roots all over arround, high density opsticles
and OO coil is not just suitable enough to approach to every spot;under some tree or
between some stones...when coinshooting. I do that mainly...coinshooting.
So i made hard compromise and switched back to DD (double D) coils, again...
Double D shape is much more suitable for that kind of prospecting than double O.
But if you prefer leveled terrains than i suggest you to make OO coil cose a bit
greather depth than DD coil.That was my only reason to leave OO coils for now...
No i didnt say "...no gnd connection on RX..." !? Yes there is gnd connection on RX!
Must be! But not at pcb. That's why i didnt draw gnd connection in schematic.Not to
confuse somebody who might decide to draw pcb according my schematic...Later should
scratch or cut that piece of pcb to correct mistake...
GND connection at RX should be made in coil.
Pay attention on cable lead which connect coil via R13 to pin 6 of U101a!That lead must
be connected to gnd in coil!
I am using cable with 3 separate leads and common shield. Shield and 1 lead are connected to
faraday cage at both coils...all togather in coil housing. The other 2 leads i am using for
TX and RX....Simple as that. No twisted pair effect,no hums,interferences...no false signals!
I experimented with any other combination and this one is best.
Nelson, no you can not use only 3 lead cable....Shield and 3 leads yes! It makes 4 leads at
the end.
LM308 is hard to replace...beleive me! Only replacement i would use is TL081a...
About Bipolars....i never used those. I connect 2 ordinary 10uF cpacitors like this;
+ -- + and used those instead...
No, Nelson...if you using TLxx1 no need to reroute pcb; pin to pin compatible...
About NE5532...i am not sure...why dont you try NE5534? I never tried it...
OK. Again there is (i hope) very correct schematic...at the end. Take another look.
If something wrong let me know...
Anybody migh have good will to draw pcb for it? One-sided,small...C'mon....

[Hush]

Thanks a lot Ivconic for an answer! Now I can see some corections at
your schematic, and some more options. Beside that, I'll try to put a ground
balance at control table. TNX to kt-315, man from Mars too.
By the way, does anybody know where is Geo? Hope he's OK and somewhere
at holiday.
Now back on work- Golden Sabre and coils.

Oh! I'll need that eyeglasses!
Regards!

[Max]

Hi all,

Ultimate:
TL081 could be used too but is a bit noisy. I've tested in other circuits and sometimes you couldn't note any difference, sometimes you could very easy.
Depends on many factors. Anyway, if you have them just put in sockets and just see what happens.

About fets originals were TIS75 and I've found just 2 perfect replacement parts (obsolete USA made almost impossible to find):
2N5640
U1898E

The good news, as ivconic stated, is that for this project any small signal n-fet that suit the needs would be fine.

For BF245 replacement I think you could use any of these without problems:
BF244
MPF102
MPF112
2N3819
but take care that pinouts may differ from one type to another (and also on same type for different manifacturers--- so find the right datasheet first or test then in small circuit e.g. with a led or the like).

About
"I am woried because BF245C is marked as N-Channel RF Amplifier and PN4393 is N-Channel JFET Switch?????
"
OK depends on how it's intended to be used as default. What's important here is that bf245 is a N-channel fet for small signals and then could be used as switch too cause has a wider range of applications. PN4393 is (probably) intended to work as analog switch only and can't do exact same work of bf245 (e.g. radio-frequency mixers etc) without degrading performances. This is expecially true for hi-intercapacitance devices that can't be used in hi-freq applications.
Another good issue is current:
BF245 has 30V 10mA rating
PN4393 has 55V 50mA rating (so it's better for switching bigger currents due to construction , but have for sure much more intercapacitance(s)).

Keep going on. I'm interested too!

Best regards,
Max

helo

Can someone explain how I should conect switches and potentiometers?
I will be very hapy if finaly understand that!
Thanks

[Ultimate_Haze]

to Unregistred!!!

Hi,
I have looked!
I am woried because BF245C is marked as N-Channel RF Amplifier and PN4393 is N-Channel JFET Switch?????

I am beginer but isnt there a differance???
Thanks

Hello,
Thanks for your help!
Are you share that this will be equal replacement?

If you look at datasheetcatalog.com you no.

[nelson]

Hi, yes i think this is the boring part when you have to cellect parts from here and there. But after that, the fun begans.
Regards and good luck with your project.
Nelson

Hi,
I can wate to see the results!I have ordered the same arangemend!
So,cant wait to here from you.I will have to wate more than week for my parts!
Nice job you put it together fast!!

To nelson

Hi,
I can wate to see the results!I have ordered the same arangemend!
So,cant wait to here from you.I will have to wate more than week for my parts!
Nice job you put it together fast!!

[nelson]

Hi Max.
Yesterday i got TL081 to replace LM308.
All other components are ok.
Now i hope i have the time to finish my MD this weekend.
When i get ready i ll post my results.
Regards and thanks.
Nelson

Hi Nelson,
plvr is right on single op amp...use lf356 or lf357 instead of LM308 and you would be ok. Use tl082 or others to replace lf353 that are dual.

Best regards,
Max

[Ultimate_Haze]

to Unregistred!!!

Hello,
Thanks for your help!
Are you share that this will be equal replacement?

DATASHEETCATALOG.COM BF245-2N4393

[Ultimate_Haze]

hi

Can I use 2N3819 insted of BF245C?
How do you think?
Will this be equal sustitue?
Thank

[Ultimate_Haze]

Hello,

Is there some more comon FET that can replace BF245 without change in the preformance of the unit?
And MAX why you dont like TL081 for replacement of LM308N?
Thanks

[Max]

Hi Max and Ivconic, and thanks both of you for replacement information.
Unfortunely can´t get that LM308 here. So i ll replace it with TL082 and see what´s going on.
Ivconic, th ehole pcb is build considering ICs base on it. I agree, that is a good way to test diferents alternatives on components.
Regards
Nelson

Hi Nelson,
plvr is right on single op amp...use lf356 or lf357 instead of LM308 and you would be ok. Use tl082 or others to replace lf353 that are dual.

Best regards,
Max

[porkluvr]

AGGHH

To whom it concerns:
Sponsored by: The number two, (2)

It is not recommend that you plug a dual opamp into a single opamp socket. If you have questions about whether or not you can use a particular device as a substitute, it is incumbent upon you to check the device's function and pinout! You can learn a lot from browsing manufacturers data sheets at:

ti.com (often more "windy" than necessary"
national.com
fairchild-ic.com
linear.com
analog.com (one of my favorites)
maxim-ic.com
This is just a few, the list is much longer. Aren't sure who to ask? then try:
http://www.datasheet.in/ What's that, the Navajos?

Datasheets are free to download. If you can read (too much to expect?) and post on this website you can also access datasheets and please quit being rediculous.