Building The Ultimate Delta Pulse using KT315 pcb

[tomari]

Hello my friends, i would like to synopsis all the info for the noob DIYers like me into one thread and with your help, build the best DP i can.

intro:
i have already built 2 other DP using one sided turkish PCB:
First was fairly good - Died after 1 year of use because PCB degraded and parts rusted, last bullet on it was when my friend connected the battery wrong and smoked it like meat
Second i tried to make better than first but it was a little unstable and worked for 4-5 months and stopped, because it was unstable, i was never in the mood to fix it anyway

target:
the mods i saw in KT's plans, i have read about them in the forums one by one and the justification of each one, so in theory, this must be the ultimate DP for me!!

i could ask him by PM each of my questions but this is not fair! its not a secret to nobody! im sure there are many others like me, who are confused of all the fragmented info here and there, so this is gonna be a step by step guide kind of thread, i would like to keep it in the subject of KT's PCB and everyone that has a good experience on it could participate!

so step one and two are done:
1) Get the pcb: ordered yesterday, counting moments untill i get it!!!
2) Read everything about this PCB: Read 250 pages yesterday, now i have more questions!!

Next steps (plan the next moves, make no mistakes!):
3) Parts planning:
~ a) IC's, i have read somewhere in this forum about 4538 and 4066: is getting CD4066BE and CD4538BE the best we could do? i have read that other part numbers are ok, but there is a limitation in minimum timming or something? unfortunately i couldn't find this post again, so if anybody can make it clear, please do!

~ b) use no IC sockets, little more inductance, not acceptable for "the best we can do" concept! please confirm

~ c) Power: what about power source? is it best to use 18v and regulate to 12v? if yes what is the best way? i have read in a post that using 7812 for is a way to go, but is this any good for this pcb design or will it introduce more noise? what about two huge 10000uf 35v capacitors? please look at the attached picture is this the right way for the 7812 ?

~ d) other parts that need attention: are there versions of TL062, 556 and 357 that make a difference like the 4066 and 4538 if i chose a different verion of them?

4) shield:
~ a) i have seen pictures of KT spraying the inside of the box with carbon, where can i find this "spray"? can i make my own? how?

~ b) i have seen pictures of KT making a DIY shield under the PCB, can i use full copper pcbs to make a little box around the DP pcb and connect it to the shield connection of the PCB ?

there are many other questions but i dont want to make this a huge post that nobody can read (not from the beggining!) lets make these two sections clear, then proceed to next ones!
i will edit this post and put the answeres (and new questions) so anybody can read it in one go and have everything nice and tidy!!

next steps are:
testing the DP for noobs
tuning the DP for noobs
coils for noobs

[bernte_one]

wish you much luck for this Project
at the end you will see it is harder to make a clear documentation then all other

but i hope you do it good

[Silver Dollar]

Well the 4066 is better than a 4016, the 4038 works at smaller widths than other chips so those are the best to use.

I would sub a TL072 for the TL062. It draws more current but is a bit quieter.

You can get some graphite spray at tractor supply it's called EZ Slide; http://www.tractorsupply.com/en/stor...l?cm_vc=-10005

The 7812 is a bit of a brute force method to regulate the power it needs 2.5V to function you might look for a low drop out regulator.

[tomari]

hello thanks for the answer, the real question around the 4066 is:
CD4066 mc14066BCL hef4066 tc4066 all realy the same??
CD14538, MC14538, CD4538, HCF4538 all realy the same??
worth digging to find cd4066 and cd4538 ??
worth digging to find lf357h(original metal can packege) or LF357N is just fine?

about the regulation, does the voltage regulation make things better *while( detecting?? or its just to keep settings the same for a period of 30mins of continus detecting (because voltage does drop slowly 12,01 / 12,00 / 11,99) ?? i dont care about the second, but i care about the first

its a shame we cant edit first post to add answers but it is ok, maybe i will make a last post to include everything:

4) shield:
~ a) i have seen pictures of KT spraying the inside of the box with carbon, where can i find this "spray"? can i make my own? how?



Graphite based sprays, suitable for traktors, motorcycle chains etc. widely available in the market

geez we got the first answer !!!

[Silver Dollar]

Well different letters might give a wider voltage range but won't help your detector much (if any).

The LF357 would make a big difference if you could get the best chip there. The TL072 would be an easy
upgrade.

The 12V regulator will get hot and not let you run as long but no improvements in detection. An area that could be
worked on is the -E generator. A real regulator there would be better. Increasing the +E -E would help too but you
have to be sure the transmit is still biased properly...

[tomari]

c) Power: what about power source? is it best to use 18v and regulate to 12v? if yes what is the best way? i have read in a post that using 7812 for is a way to go, but is this any good for this pcb design or will it introduce more noise? what about two huge 10000uf 35v capacitors? please look at the attached picture is this the right way for the 7812 ?



The 12V regulator will get hot and not let you run as long but no improvements in detection. An area that could be
worked on is the -E generator. A real regulator there would be better. Increasing the +E -E would help too but you
have to be sure the transmit is still biased properly..
since there is nothing we can do best in this pcb as is, i hold this as a todo for a real electronics gangster like you know who you are!!



a) IC's, i have read somewhere in this forum about 4538 and 4066: is getting CD4066BE and CD4538BE the best we could do? i have read that other part numbers are ok, but there is a limitation in minimum timming or something? unfortunately i couldn't find this post again, so if anybody can make it clear, please do!



Well different letters might give a wider voltage range but won't help your detector much (if any).

The LF357 would make a big difference if you could get the best chip there. The TL072 would be an easy
upgrade.

I would sub a TL072 for the TL062. It draws more current but is a bit quieter.

i have TL072 and will make a comparison against LF357 for sure, but what do u mean by " The LF357 would make a big difference if you could get the best chip there" what is the best chip ??

[Silver Dollar]

Oops I meant that the first op amp (preamp) sets the noise floor so a better chip than LF357 will gain you
some depth. Not sure how to choose a good substitute. The NE5534 is used on other PI's to good results.
The MAX 410 might work too... The key is low noise and the ability to come out of saturation quickly and
cleanly. That last function is not well documented on spec sheets so trial and error is the way to find the best.

I've found a 2 stage preamp works much better but not sure how to implement it on Delta (cause of the delta)..

The TL072 is a sub for the TL062. That is a no brainer as it is in the same family so will work the
same.

[mohandes]

Well the 4066 is better than a 4016, the 4038 works at smaller widths than other chips so those are the best to use.

I would sub a TL072 for the TL062. It draws more current but is a bit quieter.

You can get some graphite spray at tractor supply it's called EZ Slide; http://www.tractorsupply.com/en/stor...l?cm_vc=-10005

The 7812 is a bit of a brute force method to regulate the power it needs 2.5V to function you might look for a low drop out regulator.

4038؟؟؟or 4538?
tle2072 better than all.and millatery lf357 name is lf357h.
please say me more about You can get some graphite spray at tractor supply it's called EZ Slide; http://www.tractorsupply.com/en/stor...l?cm_vc=-10005 .need help more.
regards

[mohandes]

Oops I meant that the first op amp (preamp) sets the noise floor so a better chip than LF357 will gain you
some depth. Not sure how to choose a good substitute. The NE5534 is used on other PI's to good results.
The MAX 410 might work too... The key is low noise and the ability to come out of saturation quickly and
cleanly. That last function is not well documented on spec sheets so trial and error is the way to find the best.

I've found a 2 stage preamp works much better but not sure how to implement it on Delta (cause of the delta)..

The TL072 is a sub for the TL062. That is a no brainer as it is in the same family so will work the
same.

I've found a 2 stage preamp works much better but not sure how to implement it on Delta (cause of the delta)..
please say me.
regards

[kt315]

I've found a 2 stage preamp works much better but not sure how to implement it on Delta (cause of the delta)..
please say me.
regards

Delta works on relatively big FIRST STROBE DELAY that begins from 30-40us. so this why you do not need in 2 stage preamp.
but if you want to re-tune Delta for gold nuggets hunting with small coil you maybe will want to decrease FIRST STROBE DELAY
to 'Eric Foster's 5us delay WOW! result'. then experiment with 2 stage, however remember first opamp
has to be (x)FET - you can not stay NE5534 like 1st opamp, be cause NE5534 is NOT JFET opamp and simply will not work in Delta.

[tomari]

i have read 1.000.000 posts and LF357 us wall everybody hits on!
so the best i can do without any other PCB modification is LF357H ?

TL072 instead of TL062 and this is pretty much all we can do
while reading datasheets i found:
TL072B__ better than TL072A__ better than TL072I__ better than TL072C
TL062B__ better than TL062I__better than TL062A_ better than TL062C__

ALSO mohandes, the military version of LF357 is LF357M not H
the H version is a Metal Can Package and the only difference i can read in datasheets is the heat disipation when there is airflow (better) and when there is no airflow (worst)
has anybody any better detecting experience using the H version of LF357 ?

[mohandes]

i have read 1.000.000 posts and LF357 us wall everybody hits on!
so the best i can do without any other PCB modification is LF357H ?

TL072 instead of TL062 and this is pretty much all we can do
while reading datasheets i found:
TL072B__ better than TL072A__ better than TL072I__ better than TL072C
TL062B__ better than TL062I__better than TL062A_ better than TL062C__

ALSO mohandes, the military version of LF357 is LF357M not H
the H version is a Metal Can Package and the only difference i can read in datasheets is the heat disipation when there is airflow (better) and when there is no airflow (worst)
has anybody any better detecting experience using the H version of LF357 ?

thanks.
tle2072 better or tl072b?
for lf357 i search very, but dont fin better

[sinclairuser]

sometimes there are two types of metal packages for chips, one type is round the other is like a normal dip package.
also dont forget ceramic packages, some variants of those out perform metal can, it depends on the chip.
i have a source for obsolete components and i can tell you they are not cheap, 99 times out of a hundred metal can packages have no real benefit.
but i personally prefer ceramic chips to plastic, at the end of the day it comes down to personal preference, and how much you are willing to pay to build your project.
you should listen to kt315, if anyone knows what works best in the DP its him.

[tomari]

yup i can confirm somewhat this about ceramic chips, i remember experimenting with the turkish pcb, i had a couple of 4538 s in ceramic package and they clearly outperformed plastic ones (or were they 4066? i will check it out) i dont know how my local supplier,who doesnt have other basic things, got them since they where M(ilitary) ones. unfortunately they burnt up with the machine.

so there is a square lf357 metal package that outperforms the plastic one?

kt is the master yoda of DP and the force is with him

[tomari]

hello again!! i've read at thunting a post that:
BC557 must be BC557C
BC546 must be BC546B

is this true?
can u confirm?