Minipulse Rev D first attempt

[Impulse]

Hey guys i have the inductance meter heres a picture, now how do i use this properly? eg coil on or off board? setting 2H?

[ATTACH]35761[/ATTACH]

thanks in advance for any help

OK guys the induction meter I bought has stopped working so now I have to return it also my laptop screen has popped so now I am left with 2 barracuda pi's that are useless (Qiaozhi has one and is trying to fix it but doesn't seem likely) and a minipulse plus that does not work as expected (is there a theme here?) so I have spent over £140 on these kits and a scope, why is it so dam hard all the time?

[Qiaozhi]

OK guys the induction meter I bought has stopped working so now I have to return it also my laptop screen has popped so now I am left with 2 barracuda pi's that are useless (Qiaozhi has one and is trying to fix it but doesn't seem likely) and a minipulse plus that does not work as expected (is there a theme here?) so I have spent over £140 on these kits and a scope, why is it so dam hard all the time?

That's a real run of bad luck!

Regarding the PCB you sent to me for analysis ..... I assume you've been following the Baracuda thread?
Your board will most certainly end up in working condition. I've already had it detecting a Victorian penny at 12 to 13". Unfortunately the Baracuda design is less than perfect, and due to some design faults the 40106 has expired yet again. Some new ones have arrived, and I plan to get back to it in the next few days.
You will receive the detector back in working condition complete with modifications.

[kt315]

please

Baracuda design is less than perfect
---
pls if you mean somebody design do not write that. Baracuda Apberg's (or whom, notice) design is less than perfect will
be very ok in this mention case. NOT original one.

original one is in WORKING GOOD PERFECT CONDITION. was and will.

[Qiaozhi]

Baracuda design is less than perfect
---
pls if you mean somebody design do not write that. Baracuda Apberg's (or whom, notice) design is less than perfect will
be very ok in this mention case. NOT original one.

original one is in WORKING GOOD PERFECT CONDITION. was and will.

Do you have the schematic for the original Baracuda design?
If the original is ok, then somewhere along the line there have been a number of modifications which have made it "less than perfect".
The only so-called "original" is very difficult to read, as some of the net names and component values are corrupted.

[Impulse]

That's a real run of bad luck!

Regarding the PCB you sent to me for analysis ..... I assume you've been following the Baracuda thread?
Your board will most certainly end up in working condition. I've already had it detecting a Victorian penny at 12 to 13". Unfortunately the Baracuda design is less than perfect, and due to some design faults the 40106 has expired yet again. Some new ones have arrived, and I plan to get back to it in the next few days.
You will receive the detector back in working condition complete with modifications.

Hi Qiaozhi i really could do with a turn of good luck and soon! thank you for your help with my barra i really appreciate it! i will have to dig out the other one at a later date. Now that inductance meter i bought it turned on this morning so i put it on my 3dss coil and i got 0.35 on the lowest setting i will still send it back but i thought i would note that it has managed to work once i think. is 0.35 anything to go on? or is it just rubbish?

[kt315]

Do you have the schematic for the original Baracuda design?
If the original is ok, then somewhere along the line there have been a number of modifications which have made it "less than perfect".
The only so-called "original" is very difficult to read, as some of the net names and component values are corrupted.

George, IMO the schematic was especially changed by somebody doing it wrong. so it has mistakes.
but the generator seems maybe has right values. i still hope to get the pcb pics of revision D (papa alex's board revision is B)
to see more.

[Qiaozhi]

Hi Qiaozhi i really could do with a turn of good luck and soon! thank you for your help with my barra i really appreciate it! i will have to dig out the other one at a later date. Now that inductance meter i bought it turned on this morning so i put it on my 3dss coil and i got 0.35 on the lowest setting i will still send it back but i thought i would note that it has managed to work once i think. is 0.35 anything to go on? or is it just rubbish?

In that case your coil is being measured as 350uH. Sounds reasonable.
The LCR meter looks quite good in the photo, but you can only really tell when you have it in your hands. At that price, it was worth a punt.

[Qiaozhi]

George, IMO the schematic was especially changed by somebody doing it wrong. so it has mistakes.
but the generator seems maybe has right values. i still hope to get the pcb pics of revision D (papa alex's board revision is B)
to see more.

In the original schematic that I posted it looks like the 40106 is actually connected between +5V and -5V, and some of the pull-up resistors are connected to +5V, and the pull-down resistors to -5V. It would be nice to know how the original design was configured. Someone appears to have taken the design and made a real screw-up.

[kt315]

its wrond and that i mean above. i detaily did learn papa alexis board pics and his schematics. 40106 is connected to -5V and gnd.
pics of layout of both sides are perfect, no mistakes. i did a superposion of his pics in photoshop
and they are sure accurate.



Someone appears to have taken the design and made a real screw-up.

yes. no doubts.

[ODM]

N-JFET sample switches are further proof of timing logic being supplied at 0/-5V. Their gates are directly connected to cmos logic outputs, they would forward bias the JFET gates if run between +5V/-5V. This would couple logic output into integrator input through the gate diode.

[Old cart]

Do you have the schematic for the original Baracuda design?
If the original is ok, then somewhere along the line there have been a number of modifications which have made it "less than perfect".
The only so-called "original" is very difficult to read, as some of the net names and component values are corrupted.

Precisely the point I tried to make earlier. This is a common trend of many of these discussions. We often try to reverse engineer many detectors, this is not a perfect process. Then folks start to mod the reversed engineered design. That is fine but the degree of engineering skill varies widely. Multiple schematics are produced some have mods of mods. Components are changed to get the moded detector to work. Ultimately someone gets the detector to work, but only that specific detector. This is not a very effective way to produce a reproducible working detector.
While I myself like to tweak and adjust things I have no expectations that my modified designs could be easily reproduced. Indeed without a good scope, multimeter and LCR meter it is unlikely that someone could get one to work UNLESS they had a great deal of knowledge.
I don't know how to fix this process but it is my OPINION that something between the process we currently have and disciplined engineering could work. Any ideas or comments?

Maybe we should start a new thread.

[Qiaozhi]

N-JFET sample switches are further proof of timing logic being supplied at 0/-5V. Their gates are directly connected to cmos logic outputs, they would forward bias the JFET gates if run between +5V/-5V. This would couple logic output into integrator input through the gate diode.

Exactly. I did point that out earlier when I first took a look at the Baracuda design. The confusing thing is that the so-called "original" schematic doesn't show that. Perhaps it's never been correct, and that's why it was changed to 0V and -5V for the supplies, but whoever did that forgot to correct the pull-up resistors.

[Qiaozhi]

Precisely the point I tried to make earlier. This is a common trend of many of these discussions. We often try to reverse engineer many detectors, this is not a perfect process. Then folks start to mod the reversed engineered design. That is fine but the degree of engineering skill varies widely. Multiple schematics are produced some have mods of mods. Components are changed to get the moded detector to work. Ultimately someone gets the detector to work, but only that specific detector. This is not a very effective way to produce a reproducible working detector.
While I myself like to tweak and adjust things I have no expectations that my modified designs could be easily reproduced. Indeed without a good scope, multimeter and LCR meter it is unlikely that someone could get one to work UNLESS they had a great deal of knowledge.
I don't know how to fix this process but it is my OPINION that something between the process we currently have and disciplined engineering could work. Any ideas or comments?

Maybe we should start a new thread.

I'm somewhat inclined to take the Apberp REV-2 version and fix it so that everything functions correctly, without making so many changes that it's not the same design. Then create a "Geotech Baracuda REV-A" version, as I think simply changing it to REV-3 will confuse everyone. IMHO it would best just to draw a line under the existing stuff and start again.

[Old cart]

Exactly. I did point that out earlier when I first took a look at the Baracuda design. The confusing thing is that the so-called "original" schematic doesn't show that. Perhaps it's never been correct, and that's why it was changed to 0V and -5V for the supplies, but whoever did that forgot to correct the pull-up resistors.

Maybe we should just stay with the 0 and -5V design. Ray has proven that this works if the pull up values are adjusted. But as mentioned in my last post we should not conclude that this is engineering that will produce a repeatable design. Unless someone has and commits the time to verify it will work under all conditions, this is more of a variant.

As for the original design being good, I would suspect that this is more of a garage design and that the designer also hand built each one and MADE it work. I say this only because of the marginal engineering practices.
I do not mean to insult anyone here but we must recognize that this design has merit but in the current state needs some work.

[Old cart]

I'm somewhat inclined to take the Apberp REV-2 version and fix it so that everything functions correctly, without making so many changes that it's not the same design. Then create a "Geotech Baracuda REV-A" version, as I think simply changing it to REV-3 will confuse everyone. IMHO it would best just to draw a line under the existing stuff and start again.

As long as it is clear what REVISION anything is we have made a huge step in the right direction. I know how tough it is to take random data and make sense of it. That is exactly what I am trying do right now in creating a Surf PI build guide. It takes many hours of study...