Delta Pulse

[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

[PulseStarIIUser]

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

[PulseStarIIUser]

Thanks Gentlemen,

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

Best wishes,

Bob

[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

[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.

[1843]

Here is my Delta Pulse:

[1843]

Soldered IC sockets photo

[dan129]

good job

Here is my Delta Pulse:
[ATTACH]1551[/ATTACH]

hi 1843, good job. which are the performance and which type of coil you used. thx

[1843]

hi 1843, good job. which are the performance and which type of coil you used. thx

Hi dan129,
It has a problem and its detection is poor...
I shall repair it next week since I haven't oscilloscope now.
My coil is 70 x 70cm.

cheers

[kt315]

anybody can give me speedy reply? where is a correct polarity of VD12 and VD13 - on the PCB or on the schematic? (because the connections are mirrorly different). sorry I have see this question in forum, but I can not find up again the answer via Search
tia.

[Geo]

anybody can give me speedy reply? where is a correct polarity of VD12 and VD13 - on the PCB or on the schematic? (because the connections are mirrorly different). sorry I have see this question in forum, but I can not find up again the answer via Search
tia.

The schematic is sorrect. Both XR71 and Delta-Pulse schematics are the same and correct with R35..VD12 and R36 VD13. I have the original XR71 so i am sure.

[kt315]

thanks lots, Geo! ... have a nice day!

[1843]

LF357 Output

Hi all,
My DP works very unstable....
I looked at the waveform of D4 pin6; It looks bad, Doesn't it?



Thanks for any help.

[1843]

Instability increases when the Gain pot be set to max...
What is your opinion about the D4 waveform?

[Geo]

Instability increases when the Gain pot be set to max...
What is your opinion about the D4 waveform?

Hi. I will try to open my DP and to see the waveforms.
1. What is the frequency of your DP?
2. Do you try it on the Lab or at the field
3. What coil do you use. As i remember when i made some tests with different coils, when the coil had little impedance the DP was unstable.

(I read your message)