Delta Pulse

[Qiaozhi]

Hi. I tried it one's before time. I connected the shield at -E, +E, and gnd. At Delta Pulse was the same . I believe because there are capacitors between e, +e and gnd. Finally i connected it to +E.
Wishes

As far as an AC signal is concerned, the power supplies and ground are the same. Only when dc levels have to be taken into account will you need to choose the correct one. For a Faraday shield it doesn't really matter where you make the connection (+V, -V or GND). However, digital ground is usually kept separate from the analog ground to minimize interference, so it's probably not good to use this for the shield.

[Geo]

Yes! To ground. In this case GND is +pole....althought there is digital ground on pcb....i am wandering about it? I never used f.cage,since my previous devices worked on low freq. and i made only large coils so far...
It is good question! Where to connect shield??? On +pole or to digital ground?
Any ideas?
Geo?
:confused:

Hi. I tried it one's before time. I connected the shield at -E, +E, and gnd. At Delta Pulse was the same . I believe because there are capacitors between e, +e and gnd. Finally i connected it to +E.
Wishes

[PulseStarIIUser]

Thanks Gentlemen,

I need one more clarification. Do you suggest to connect aluminium faraday wire to positive pin (Pin #4)?

Best wishes,

Bob

[PulseStarIIUser]

Thanks Ivconic and Chris2. I appreciate your help very much!

[Chris2]

Where to connect the shield....?

Hi Ivconic, PulseStarIIUser

“…Where to connect the shield….” It’s a very good question. I would not connect any shield in any design direct to "digital" ground. By the way the Delta Pulse does not have a digital ground. The Delta Pulse has a "virtual analogue ground" generated by IC D6A to operate the OPAMP’s.

I looked at some other circuits like Whites PI 2000-3000 schematic or DBP2010. The Whites PI has the shield connected to "minus" pole of the battery. The DBP2010 has it connected to the "plus" pole. That’s the opposite!

Here my conclusion:
I would connect the shield at the nearest “power point” (electrical path) to the battery that is “seen by the coil”. This can be the “minus” or the “plus” pole of the battery, depending on your design.

Take a look at the White PI 2000-3000 schematic. Here is one side of the coil connected direct to the “minus” pole. The designer connected the shield to the “minus” pole of the battery too.
In the DBP2010 schematic is the coil direct connected to the “plus” pole of the battery and as you can see the shield (see big loop option; Elektor book, page 16 is connected to the “plus” pole as well.

In the Delta Pulse schematic is the coil direct connected to the “plus” pole (E+) of the battery. My conclusion is that I would connect the shield to the “plus” pole, because the plus pole is the nearest power point, seen by the coil.

So, Ivconic is right if he connects the shield to the plus pole in his Delta Pulse.


Any comments / critics are well come….

Chris

[ivconic]

Yes!


Yes! To ground. In this case GND is +pole....althought there is digital ground on pcb....i am wandering about it? I never used f.cage,since my previous devices worked on low freq. and i made only large coils so far...
It is good question! Where to connect shield??? On +pole or to digital ground?
Any ideas?
Geo?
:confused:

[PulseStarIIUser]

One more question about making PSII Coil

Thanks Ivconic for advice on building PSII universal coil,

I found this wire quite cheap (US $0.50/foot). It is 12 conductor wire. Do you think it will be suitable?

One more question: what to do with the aluminium shield wire? Is it to be connected to one of the terminal wires?

Thank you again,

Bob

[ivconic]

R1=???

:confused:

"With PR1(200k)+R1(680k)..."

I know this. On your picture R1 does not look as 680K.....not even close?
Not even Kohms....but in ohms??? Or picture is not clear enough....blur?
Anyway, regards!

[dan129]

too high frequency

Hi Ivconic, Geo or anyone that can help.
First of all, happy new year to everyone.
I had re-checked mi delta pulse circuit, and all seems to be working, but still no sound.
A measure fequency, it running from 400 to 650 hz.
A measure EMF, it get strong signal when i raise noise potentiometer.
When i disconect the power you can heard a fading and short sound.
Some times when you apply power to the unit, you can heard a fast cliking tone that is going down for a couple of seconds, until stops cliking very slowly.
For me it seems that the circuit is working, but it has something wrong with capacitors.
For example, almost all mi electrolitics capacitors are for 16 volts, specially C27 (220uF, 16 volts) I took a look to the pictures of other DP circuits, and i compared the size with mine, wich looks phisicaly small than the others projects.
Sorry, but i not very skilly on electronics.
In advance many thanks
Nelson

verify these values of component. while turning PR1 you should vary between 90 and 150 Hz. Perhaps the problem does not come from there, but starts already with this checking. with such a raised frequency, the coil should whirr


PR1 = 200 k or 220 k
R1 = 680 k
C1 = 15 nf
R2 = 6,8 k

NE556, i don't use LM556

[dan129]

fréquence modif.

:confused:
DAN129, what is value of this resistor you put on your DP?
I can see quite different colors than expected!?
regards!

hi ivconic,

I tested increased frequency of the DP by modifying R1 or PR1. With PR1(200k)+R1(680k) you can turn PR1 to have F = approximately 99 to 150 Hz roughly. If one decreases the value of R1, one increases the work frequency of the deltapulse. The problem it is that the coil of detection starts to whirr. I dont' remenber the value i soldered, i'am at office. bye

[nelson]

Delta Pulse capacitors

Hi Ivconic, Geo or anyone that can help.
First of all, happy new year to everyone.
I had re-checked mi delta pulse circuit, and all seems to be working, but still no sound.
A measure fequency, it running from 400 to 650 hz.
A measure EMF, it get strong signal when i raise noise potentiometer.
When i disconect the power you can heard a fading and short sound.
Some times when you apply power to the unit, you can heard a fast cliking tone that is going down for a couple of seconds, until stops cliking very slowly.
For me it seems that the circuit is working, but it has something wrong with capacitors.
For example, almost all mi electrolitics capacitors are for 16 volts, specially C27 (220uF, 16 volts) I took a look to the pictures of other DP circuits, and i compared the size with mine, wich looks phisicaly small than the others projects.
Sorry, but i not very skilly on electronics.
In advance many thanks
Nelson

I have only a list, wrote by Jean-Charles. do you mean this list?

Composant Valeur
C1 15nF
C2 1nF
C3 10nF
C4 1,5nF
C5 1,5nF
C6 1,5nF
C7 220µF
C8 10µF
C9 100nF
C10 100nF
C11 100nF
C12 100µF
C13 15pF
C14 100nF
C15 100nF
C16 100nF
C17 47pF
C18 100nF
C19 100nF
C20 100nF
C21 10µF
C22 100nF
C23 100nF
C24 100nF
C25 220nF
C26 47nF
C27 220µF
C28 100nF
C29 100µF

CI1 LM556
CI2 CD4538
CI3 CD4538
CI4 LF357
CI5 TL062
CI6 TL062
CI7 TL062
CI8 NE555
CI9 CD4066
CI10 CD4066

P1_1 47k
P2 470k
P3 22k
P4 22k
P5 10k

PR1 220k

R1 680k
R2 6k8
R3 47k
R4 5k6
R5 2k2
R6 680
R7 15k
R8 27k
R9 68k
R10 100k
R11 100k
R12 10k
R13 10k
R14 1k
R15 820
R16 12k
R17 120k
R18 120k
R19 4k7
R20 2k2
R21 47k
R22 47k
R23 4k7
R24 4k7
R25 4k7
R26 4k7
R27 4k7
R28 56k
R29 1M
R30 1M
R31 5k6
R32 330
R33 4k7
R34 22k
R35 5k6
R36 56k
R37 560
R38 10k
R39 1k
R40 12k
R41 6k8
R42 22k
R43 6k8
R44 330
R45 39
R46 2,2
R47 2k2
R48 8k2

T1 IRF840
T2 BC546
T3 BC557
T4 BC546
T5 BC546
T6 BC546
T7 BC546
T8 BC546
T9 BC557
T10 BC557

VD1 1N4148
VD2 1N4148
VD3 1N4148
VD4 1N4148
VD5 1N4148
VD6 1N4148
VD7 1N4148
VD8 1N4148
VD9 1N4148
VD10 1N4148
VD11 1N4148
VD12 1N4148
VD13 1N4148
VD14 Zener 8V2
VD15 Zener 9V1

[ivconic]

??? res

:confused:
DAN129, what is value of this resistor you put on your DP?
I can see quite different colors than expected!?
regards!

[amtech2005]

Delta Pulse

Dan129 , Nice Work !!! The Delta Pulse and also photos on dbp-2010 , A good way to start 2007 , Have a Happy New Year Too !!! Eugene

[dan129]

With 20...25 cm coil you must detect a 2Euro coin at 30 cm and a soda can (330ml) at 70..75 cm with good stability. But DP is an excellent low frequency metal detector for large objects. For small coins there are other PI detectors better than DP.
BTW you made very good pcb's

thanks géo,

not far from my home I have several stores of components, I have the choice. I make manufacture the pcb on the Web for a few euros (about 13 euros). I do not do sufficient circuit to buy materiel. it is more economic to make them realize by somebody else. I do not have to test my deltapulse yet on the ground. I have make the tests of detection at home, and there is many metal a little everywhere. Perhaps that I will have better result outside...

[Geo]

With 20...25 cm coil you must detect a 2Euro coin at 30 cm and a soda can (330ml) at 70..75 cm with good stability. But DP is an excellent low frequency metal detector for large objects. For small coins there are other PI detectors better than DP.
BTW you made very good pcb's