Delta Pulse

[bbsailor]

Check This First

1843

Look on the Mikron Delta Pulse Schematic at the +E and -E derived from the D7, D6 and D5 circuit across C7 and C8. Also look at the virtual ground that is at the output, pin-1 of D6A. Make sure that the proper +/-E voltages are on the voltage supply pins of all the ICs measured to TR8 or ground. If not, D8 or D9 may be bad. Make sure that everything with a ground symbol is connected to TR8.

I hope this helps.

bbsailor

[Geo]

Hi all.
For 1843. Check the power suply. If you use bat then maybe to be bad. Check the voltage as bbsailor wrote. If all are good then check for metals near the coil. In my lab when the coil is not at some critical position then DP sounds like canary (especially with full sensitivity and power). When is unstable check with the scope the power suply. Must be a horizontal line.

For Nelson. First make all measures that bbsailor says. If all are good check with scope pin1 of ic5. You must take a graphic like this from 1843 (the first). If and this is ok then ....to be continued....

Hi bbsailor.
Best wishes and mary christmas

Ohhh.... something yet for Nelson. Did you made a bridge between pin 2 and pin 6 of D8 :confused: (out 555)?? look your pcb.

[ivconic]

It is alive?!?!?


I just finished my fifth DP in this year.What to say? Somehow i feel satisfied
with progress i made building those.
Every of those five working very good from a start. No problems at all.
I reached the point where can be free to claim that my "machines"
are good and pretty accurate.
But i still have a lot of problems with coils!?
I just downloaded "Making a Fast Pulse Induction Mono Coil" from Joseph J.Rogowski
aka bbsailor.
Congratulations on such fine,neat and accurate theory bbsailor! I do agree 100% on
all you've been talked about.
I just made a coil; 26cm diamm. 25 windings, wire 0.35-0.4mm(close...i cant tell,i
busted my mickrometer last week)....Resistance of a coil is 3.3 ohms.
Buster is 2K2,frequency is 120Hz....
Results are good. 2cm coin it can detect on 30cm distance.I guess,it could be even
much better.
It is now in "experimenting" phase so i am not using any resistivity in serie with
coil....so it is just 3.6-3.8 ohms(including cable).
After 5-7 minutes, IRF740 is still cool!?
I am, sort of confused,amazed???
But there is a certain problem. "Playing" with Treshold knob, i can put device
in position to be unstable and "sing" like canarian???? Even than,detection is
very good,fet remains cold and nothing bad happened????
I am presuming it must be something about coil, resistance or dumper....
Between those five DP's i made,this last one is the very best...i have that
feeling. I also payed a lot of attention on components. I used mostly pp caps,
wherever it was possible.I used 1% resistors also....
It will need some more experiments to establish right values of dumper and serial
resistors,but so far it is acting very good.
Until now,all previous DP's needed coil with resistances over 6 ohms, to remain fet
calm and cool,this is first one working cool with <4 ohms coil.....so far.
I will experiment more,these days.If discover something interesting i'll post here.
regards

Merry Christmas and happy new year to all!!!

[amtech2005]

delta pulse

Hello Ivconic , Check or monitor your total current from battery when adjusting your threshold , May Help to isolate problem. Start with small diameter coil first maybe ? Let us know what you find , My delta pulse is not finished yet. Merry Christmas and Happy New Year Eugene

[1843]

Good Detector

Hi all,
A good PI machine must be follower to this table.
sorry for my bad english.

Happy new year,
Best Regards

[Geo]

Hi. Delta Pulse is a low frequency detector. It is not optimised for small objects (large delay time). It is optimised to work with large coil for large objects. My DP is very good at large objects (with large coil) but medium at coins (with 10in coil). If you want a PI for coins then make it at 400Hz and try to change the delay time or (better) build an other detector. As i know (from your letters) all you are interesting for large coils so you want the detector for large objects. I believe that there is not a general purpose detector with perfect performance.
Ivconic Hi. My friend put more turns. DP needs a coil at least 600..700uH. The 1x1m coil from Mikron is about 1mH.
As for table from 1843 .... what to say. I think that are the best distances for every object that can be detect by a PI detector.
Sorry i have not a so good detector.
SO......:confused:
My REGARDS

[nelson]

My delta pulse not working good

Hi again, well i have check my delta pulse and i found some missed conections that by now are connected.
Has i said, the detector has power on the coil (440 mH). No metal detection. Coil resistance 1.8 ohms. Damping resistor 3 ohms. Sometimes sound comes on with a high tone that is decresing to the point you can get a little cliking and varing it with TRSHOLD. But sometimes you don´t get the sound thru the speaker. it looks that this happends after the detector is unpluged from the batery for a while. Also when the sound comes, it feels a little unstability.
I haven´t check pin 1 of IC 5 jet.
I also replacedIC 8 and IC 9, but nothing really change.
I m not electronics expert, this is just a hobby for me, so i really need more details from the circuit. I also traid to see the pictures publish on the forun, to see if i had made any mistakes when i conected the capacitors polarity and diodes polarities. I m really turning confusing with this project, so any experience like geo and Ivconic will be very appeciated.
ivconic, i also tried to follow some pictures and after that i burn LM 556, that now is NE 556.
I forgot to said, that this is a one side PCB, that i had fixed with jumpers to get a two side kind PCB. By now i m still cheking if i had made a bad or missed connection, but for me everything looks like a good job.
In advance, many thanks
Nelson
Santiago-CHILE
SA

[nelson]

My delta pulse not working good

Hi again, well i have check my delta pulse and i found some missed conections that by now are connected.
Has i said, the detector has power on the coil (440 mH). No metal detection. Coil resistance 1.8 ohms. Damping resistor 3 ohms. Sometimes sound comes on with a high tone that is decresing to the point you can get a little cliking and varing it with TRSHOLD. But sometimes you don´t get the sound thru the speaker. it looks that this happends after the detector is unpluged from the batery for a while. Also when the sound comes, it feels a little unstability.
I haven´t check pin 1 of IC 5 jet.
I also replacedIC 8 and IC 9, but nothing really change.
I m not electronics expert, this is just a hobby for me, so i really need more details from the circuit. I also traid to see the pictures publish on the forun, to see if i had made any mistakes when i conected the capacitors polarity and diodes polarities. I m really turning confusing with this project, so any experience like geo and Ivconic will be very appeciated.
ivconic, i also tried to follow some pictures and after that i burn LM 556, that now is NE 556.
I forgot to said, that this is a one side PCB, that i had fixed with jumpers to get a two side kind PCB. By now i m still cheking if i had made a bad or missed connection, but for me everything looks like a good job.
In advance, many thanks
Nelson
Santiago-CHILE
SA

[nelson]

My Delta Pulse pictures

hera are pictures of my DP.
Nelson

Hi again, well i have check my delta pulse and i found some missed conections that by now are connected.
Has i said, the detector has power on the coil (440 mH). No metal detection. Coil resistance 1.8 ohms. Damping resistor 3 ohms. Sometimes sound comes on with a high tone that is decresing to the point you can get a little cliking and varing it with TRSHOLD. But sometimes you don´t get the sound thru the speaker. it looks that this happends after the detector is unpluged from the batery for a while. Also when the sound comes, it feels a little unstability.
I haven´t check pin 1 of IC 5 jet.
I also replacedIC 8 and IC 9, but nothing really change.
I m not electronics expert, this is just a hobby for me, so i really need more details from the circuit. I also traid to see the pictures publish on the forun, to see if i had made any mistakes when i conected the capacitors polarity and diodes polarities. I m really turning confusing with this project, so any experience like geo and Ivconic will be very appeciated.
ivconic, i also tried to follow some pictures and after that i burn LM 556, that now is NE 556.
I forgot to said, that this is a one side PCB, that i had fixed with jumpers to get a two side kind PCB. By now i m still cheking if i had made a bad or missed connection, but for me everything looks like a good job.
In advance, many thanks
Nelson
Santiago-CHILE
SA

[nelson]

bbsailor, i forgot to check this out.
Yes the damping resistor is 5 ohms and the coil 1.8 ohms.You said that the damping resistor must be btw 500 ohms and 1 K. So if i use the 5 ohms damping resistor, what can work wrong ?
regards.
Nelson

[bbsailor]

5 Ohm Damping Resistor

Nelson,

If you use a coil that is 1.8 ohms and a 5 ohm damping resistor, your current fall time will take 360 ms and you will miss all targets and generate a lot of heat in the coil, damping resistor and MOSFET.

The 5 ohm damping resistor value is wrong.

Look at all the PI schematics on the Geotech web site and see that most coil damping resistors are between about 400 and 1000 ohms.

The damping resistor is the resistor that is in parallel with the coil.

I believe this 5 ohm damping resistor, that you are using, is one of your problems.

Post the schematic of the PI metal detector that you are building so we can help.


bbsailor

[ivconic]

Huh!

!

Thanks Amtech 2005!
"Buster is..."
When i am tired...i am really,really tired! Ha,ha,ha....
I spend few days repairing some damn TV set.Changed everything arround
flyback....Nothing! After few days i found out that "buster" capacitor
lost capacitance....Sheeesh!!! Easiest posiblle mischief!
That's why i have "buster" word on my mind constantly!?
I am buster...busted by "buster"!? Sheeesh!
Well,
I found out what was the problem with Treshold knob!
Damn potentiometer(10K) was broken inside!? It supposed to be brand
new? I just bought it in the store!I do not have another with same
value so i put 22K....It is working fine,although when reach the max.
end coils stops detecting? But only last milimeter of scale...No big
deal for now,until find another new 10K...
DP now works even better! Frequency is 270Hz now,dumper is 1K2.
I also rearrange new coil. 26cm diamm, 0.23mm wire,25 windings...
It can detect 2 cm coin now on 35 cm distance...maybe even more if
adjust all properly.
Geo was very right! Dumper resistor has not noticeable influence on
overall behavior on lower frequencies. I had to rise frequency to
270Hz, than to experiment with dumper values, and observe, and
quite differences occured than!? Bravo Geo!
Now is very easy to adjust coil,dumper and few more things.All changes
and adjustments are easy appreciable, even without scope.
Overall performances also rised now.
To those who just started making DP, i suggest to start with higher
frequencies,let's say 300-500Hz. It is much easier to understand how
it supposed to work.Later,when experienced a bit, they can switch to
some lower frequency, let's say 150-100Hz...
Dumper should not exceed upper than 1K5 and lower than 860ohm for now.
Later (even better if use scope) man can experiment with other values.
Of course dumper value is directly dependable of coil and its datas...
So it means(for the start) higher frequency,thin wire(0.2-0.3mm) and
smaller diammeters of coil(18-28cm)...It showed as easier way to me.
Again bbsailor explained this much detailed and better than me, so i
suggest to everyone,first to read his article than to experiment further.
Regards

[ivconic]

more...

:confused:
Nelson,friend, you made terrible mistake!
You are confusing "dumping" resistor with serial (with coil) resistor!
Dumper or dumping resistor is already on schematic,valued as 2K2. Of
course this is not obligated value, depends of coil type mostly.
But "serial" resistor is not sketched on schematic! This probably
confused you?
Dupming resistor should have values not less than 400-800 ohms and not
higher than 2K2 or 2K7 in 99% of cases.
"Serial" resistor should be just few ohms, if needed at all. If you
made coil with resistance over 4-6 ohms, you wont need to even think
about "serial" resistor at all.I made more coils without to use any
extra resistance in serie, just a few with serial resistor...so far.
Another possible problem of yours,might be bad pcb!? You should respect
pcb that KT315 posted some time ago here.Geo too.
It is double-sided pcb,although top side is not complex at all.
I do draw my pcb's manually,it is not so hard.Vias are thick enough,
not a big deal to draw it slowly and carefully with thin marker.
We can talk here endless about possible problems that you have with
your DP, but first you have to be sure that your pcb has no mistakes at
all!
I can asure you that mentioned pcb is accurate, it works for me for the
fifth time. Only connection between 2. and 6. pin on 555 is missing.
I used simple wire and soldered over ic, and connect those pins. Not a
big deal.
Do some checkings, than we can easy help you to fix it.
best regards!

[nelson]

Delta Pulse problems

Ivconic mi friend.
Ok, what a terrible mistake i had done.
Ivconic, i really whant to thank you to clear my wrong view of delta pulse.
Today after my work i ll check the circuit again. When i place the coil without any resistor on the coil, DP started to work, but IRF 740 got very warm and also i burn LM556 that now i replaced with NE556.
Tell me if is normal that LM556 gets a little warm?
Yesterday i did´t have any signal when i measured with my EMF detector. Before i have done the mistake with the 2.2 K resistor in series, the detector had very stong field and also the coil had a loud tone sound. Now everything looks dead. Also the red led (VD16), never ligths on, it ligths a few seconds when you turn of the detector.
Well this looks that will be a big work for me.
In advance many thanks and best wishes to you mi friend.
Nelson
Santiago-CHILE
SA.

:confused:
Nelson,friend, you made terrible mistake!
You are confusing "dumping" resistor with serial (with coil) resistor!
Dumper or dumping resistor is already on schematic,valued as 2K2. Of
course this is not obligated value, depends of coil type mostly.
But "serial" resistor is not sketched on schematic! This probably
confused you?
Dupming resistor should have values not less than 400-800 ohms and not
higher than 2K2 or 2K7 in 99% of cases.
"Serial" resistor should be just few ohms, if needed at all. If you
made coil with resistance over 4-6 ohms, you wont need to even think
about "serial" resistor at all.I made more coils without to use any
extra resistance in serie, just a few with serial resistor...so far.
Another possible problem of yours,might be bad pcb!? You should respect
pcb that KT315 posted some time ago here.Geo too.
It is double-sided pcb,although top side is not complex at all.
I do draw my pcb's manually,it is not so hard.Vias are thick enough,
not a big deal to draw it slowly and carefully with thin marker.
We can talk here endless about possible problems that you have with
your DP, but first you have to be sure that your pcb has no mistakes at
all!
I can asure you that mentioned pcb is accurate, it works for me for the
fifth time. Only connection between 2. and 6. pin on 555 is missing.
I used simple wire and soldered over ic, and connect those pins. Not a
big deal.
Do some checkings, than we can easy help you to fix it.
best regards!

[Geo]

Hi Nelson. At my DP 556 is always cold. I don't understand what to looking for it?