Analysis this schematic

[mohandes]

If that last scope shot was indeed U1-3 and U4-6, then there is something wrong. It might be as Golfnut said - so much gain that the amplifier is oscillating. Soldering a low pf capacitor across the 1.5M resistor (R20 on Georgi's schematic) might clear that up. I think 10pf might be a good value but it's hard to say what would be best without experimenting. If 10pF works, then that should be good enough.

That noisy display does not mean that U4 is bad, only that U4 does not like its environment.

After that noise gets cleaned up, that signal needs to be looked at up close, (with the coil attached). That is where you look to determine if your damping resistor R6 is a good match for your coil.

edit: I saw that nastiness and wondered about what to make of it, but I was under the impression that those two signals were on U5; the Z1 and INH inputs. The U5 outputs X, Y, and Z looked OK so I said nothing about it.

ok you think good ne5534?
and incredible things : imeasure all waves on oscillogram and say to you( dont take picture)
but when i measure U5-6,U5-9,U5-11 i angry,i set pin 10 second 4538 on 100mks but when look these pins and meaure not good , and WHAT DO YOU THINK?thanks,where i am mistake or ....
thanks

[mohandes]

You have some nasty oscillation in Rx

Is it possible that there is some strong transmitter running nearby? There is also a possibility that you are picking up some flux of a switching power supply. Is it possible for you to use batteries instead? And try to connect your coil with a meter or so of a cable and place a coil away from other devices on the bench.

I tell my self every time when you have not scope why work?
maybe all davor, because i work in lab and i put the coil under the Worktable, and i use the power supply in lab because i think it is good,

or so of a cable and place a coil away from other devices on the bench, I think your means Distance coil of worktable.ok

[Davor]

You have some nasty oscillation in Rx

Is it possible that there is some strong transmitter running nearby? There is also a possibility that you are picking up some flux of a switching power supply. Is it possible for you to use batteries instead? And try to connect your coil with a meter or so of a cable and place a coil away from other devices on the bench.

[mohandes]

Hi my dear gurus and best friend
mr porkluver ,mr georgi,mr davor,....
you can see my adjustment for pin6 ne5534( by nulling : i connect pin3 ne5534 to gnd by wire and coil not connected)IN MY MULTIMETER PICTURE this value is -0.192volt
second picture for U1-3 and U4-6 but all of you attention this level coil not connection(it is additional for myself)AND wire disconnect of U4-3 to gnd
and the finall PICTURES U1-3 and U4-6 WHEN coil onnection,i put three picture for 3 kind different of Time/Div.Alos wire disconnect of U4-3 to gnd

look and tell me it is good or no.
thanks

[porkluvr]

If that last scope shot was indeed U1-3 and U4-6, then there is something wrong. It might be as Golfnut said - so much gain that the amplifier is oscillating. Soldering a low pf capacitor across the 1.5M resistor (R20 on Georgi's schematic) might clear that up. I think 10pf might be a good value but it's hard to say what would be best without experimenting. If 10pF works, then that should be good enough.

That noisy display does not mean that U4 is bad, only that U4 does not like its environment.

After that noise gets cleaned up, that signal needs to be looked at up close, (with the coil attached). That is where you look to determine if your damping resistor R6 is a good match for your coil.

edit: I saw that nastiness and wondered about what to make of it, but I was under the impression that those two signals were on U5; the Z1 and INH inputs. The U5 outputs X, Y, and Z looked OK so I said nothing about it.

[porkluvr]

edit:your means i measure pin3 ne555 and pin6 ne5534 ,ok but in this picture not ok ne5534?why?,i set U1-3 on 150Us and U1-2 on 120Hz.
ok just need measure it?dont need measure U5-11,10,9 and U5-14,15,4(ic 4053)
ok i measure all ascillogram again and your wanted

In frame #171 you identified this scope shot as pins 3 and 6, and that was the CD4053 you were probing. Or, at least I thought so.

I want you to change your Alex schematic so that it agrees with Georgi schematic, as follows:

NE5534 = U4
CD4053 = U5

Will you do that? You need to or else I am gone because I am tired of this goat roping expedition.

Then tomorrow (or whenever, no hurry), I would like to see:
U1-3 (CH1)
U4-6 (CH2)

EDIT: Whatever THIS scope shot is, that bottom trace looks really suspicious, so let's please figure out what it is and maybe take another look at it. And could we please have these scope shots a little better in focus? Step back about 25cm and see it that helps.

[mohandes]

Hi guru porkluvr and golfnut
first sorry me , i think both of them think ne5534 dont work well, but i adjust it by nulling ( porkluvr said),when i want adjust all TP points not change and red LED always on.
second when i adjust normally ne5534(without null)i can adjust TP3 and TP4,and red LED on always too. please guide
look this picture i take it befor.yellow pin3 ne 5534 blue pin6 ne5534




I dont want to get drawn in here its exhausting.

Are you certain the preamp is not oscillating out of band - as it has no small feedback cap and stacks of gain?
S

please talk to me simple(sorry )



edit:your means i measure pin3 ne555 and pin6 ne5534 ,ok but in this picture not ok ne5534?why?,i set U1-3 on 150Us and U1-2 on 120Hz.
ok just need measure it?dont need measure U5-11,10,9 and U5-14,15,4(ic 4053)
ok i measure all ascillogram again and your wanted

[porkluvr]

hi but i measure them before,

Did you scope those two pins at the same time? I don't think so. If you cannot understand the usefulness of seeing those two signals at the same time, then you are hopeless and I have wasted my time.

edit: One thing though... it does no good to only look at 50, 100us of the signal. The real action happens between the U1-3 pulses, so lets see two pulses, OK?

Yer right, Golfnut it is pretty exhausting and I could use some relief.

[golfnut]

I dont want to get drawn in here its exhausting.

Are you certain the preamp is not oscillating out of band - as it has no small feedback cap and stacks of gain?
S

[mohandes]

hi but i measure them before,
ok please tell me all points that need i measurement .
i tomorrow go my university and check all and take clip and send for you.
for ne5534 i am nulling,then connect my coil and measure all ics in second pcb and third(oscillograms figure)
just tell me please,which points
thanks

[porkluvr]

Maybe you need to go back and address possible problem with your preamp NE5534? I made a point earlier that you need to concentrate on one problem at a time (which was sample timing on that day) but you do not need to be skipping that issue entirely.

I have corrected Alex's drawing where he showed a NE5532 being at U5. To be consistent with Georgi's drawing that should be changed to NE5534 at U4, with the CD4053 being U5.

Otay, now it does not matter which schematic I look at, they are both the same in that respect.
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@

Let us see the following (dual trace scope):
U1 pin-3 and U4-6

I'll have other requests when I get time to look some more.

[mohandes]

HI georgi and porkluvr
i finish my detector but have bad depth and discrimination,
my coil is 380UH and can find iron door 6.5cm at 4.5cm and RED LED always on and I can not set TP5(my pcb correct)

thanks

[mohandes]

hi porkluvr
look this and i sure my fist ,second, forth,pcbs are ok,and again i check the third
sorry ,my English is bad , look the clip you are understand that

http://up.toca.ir/images/1sugtssl99wig10pvgs.zip

[mohandes]

look this pages:

http://www.geotech1.com/forums/showthread.php?10894-Bulgarian-PULSE-STAR-%28-close-to-Legendary-one%29/page5

http://www.geotech1.com/forums/showthread.php?10894-Bulgarian-PULSE-STAR-%28-close-to-Legendary-one%29/page6

and look this:

03-02-2010, 01:05 AM #143
Alexismex
Guru


Join DateJun 2005Posts320

Hello Georgi,
Today i have checked and adjusted the discrim , sometimes is good sometimes it fail , i use two sheet of metal 10 X10 cm one in copper the another in iron....
please , can you give me the best adjustment for the channel X Ferros : How did you fix with RV5... at 0,, 10... 20 uS o more the window see my drawing and another thing see the photo the pot discrimination you use RV11 o RV5 tell me...you move this potentiometer to adjust the center after you push the Zero ???

Thank you very much Georgi
Alexis.

THIS FIGURE NEARLY similar my figures in #171.
what is your idea?

[porkluvr]

So, there is YOUR instruction. I will not hold your hand through this.