Replies to Minipulse Plus

[ivconic]

Ok, i did two more better videos.
I must point you on few facts to keep on mind before watching them:
1) Coil is catastrophic! I made it on hurry just to test if detector functioning at all, windings are bulky and mess. 300uH
2) I did as Davor suggested; put LF353 instead TL062, can't say that i noticed significant changes.
3) R29 (1M) is now 2M2, SAT period is bit extended, just what i wanted to achieve. Lower values do decrease period.
4) Speaker is 100 ohms, audio is significantly better than with 8 ohms speaker.
5) There are short comments under the videos, no need for further explanations... hopefully!

Qiaozhi did a good job, there is noticeable rejection which is working by logic quite opposite than conventional discrimination.
Must say that this works exactly the same as at Delta Pulse, but considering higher pps now this is having much more sense... at least to me.
Ok, enough me talking, enjoy!

First video (No Rejection):

[josewashere]

Hi Multieagle
I used the larger 6.8amp version of that battery in mine. The 3 amp version at about 30 hours of operation is big enough though. If like mine its got a switch on the side then you can hack into the side of the battery around the switch and remove it. Then you can extend the three wires of the switch and led to your own switch and led on your detector. Output lead of battery goes to mmp and input charge lead goes to charge socket on mmp

[ivconic]

Ivica - For your info: I've just replaced the LT1054 with an ICL7660A, and there was no problem with the audio. So it looks like you have a different problem.

Good to know that too, thanks!

[Qiaozhi]

Battery question:

Would a battery pack such as this work: http://www.ebay.ca/itm/12V-Genuine-3...item2a2508189c

Or same battery, larger dimensions?

Thanks

That looks a good choice.
The 3000mAh capacity will give a long detecting time with the MPP.

[multieagle]

Battery question:

Would a battery pack such as this work: http://www.ebay.ca/itm/12V-Genuine-3...item2a2508189c

Or same battery, larger dimensions?

Thanks

[Davor]

Ok, here is schematic we can work on together Davor.
You may add your mod on it or i can do that with your help, whatever.

I'll make the GB circuit on a protoboard and see what happens and what part values will be the best for it. The rest of the mods will come as I (finally) start building the device. I completed inventory of the parts on stock and I'll start making something. I should make some provisory coil just to have something to play with on a table.

[Qiaozhi]

Ivica - For your info: I've just replaced the LT1054 with an ICL7660A, and there was no problem with the audio. So it looks like you have a different problem.

[ivconic]

Ok, here is schematic we can work on together Davor.
You may add your mod on it or i can do that with your help, whatever.

[Qiaozhi]

Frankly, non-motion makes more sense, and with additional LP it will most probably take care of the residual charge injection spikes and become more calm.

The problem with non-motion is drift, which requires the operator to constantly tweak the threshold control. A third variation would be to replace R29 with a 1M pot in series with a 100k resistor, so the SAT speed can be adjusted.

Remember the MPP was created as an alternative to the Surf-PI and Baracuda designs, and to be an easier project to assemble (with a greater chance of successfully ending up with a working detector), with a faster preamp for early sampling, and the minimum of options and adjustments. It was also intended as a good experimental platform for more knowledgeable Geotech members to try out new ideas, add extra features, or make various improvements. I expect the MPP design to basically stay as it is, but other variants may emerge in the future from the efforts of various members.

Later versions of the Build Document may include an Advanced Topics appendix, which could describe additions such as how to add an adjustable SAT, and switch between motion and non-motion modes. More advanced stuff, such as GB that would need additional components, would require a new PCB layout. In this case, we would need to create a new variant, maybe called MPP-GB (for example).

[Davor]

Frankly, non-motion makes more sense, and with additional LP it will most probably take care of the residual charge injection spikes and become more calm.

[Qiaozhi]

What are the chances we to include motion/nonmotion mode switch?

To remove the SAT permanently and use non-motion, you can swap C15 (470nF) for a 100k resistor, and R29 (1M) for a 470nF cap. (See original MiniPulse schematic.)

Or - you can probably simply add a switch in series with R29 to toggle between the two modes. I haven't checked this as a solution, so you'll have to try it.

[josewashere]

[QUOTE=Qiaozhi;194910]Did you carefully follow the instructions in the Build Document? ->

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If you go through the following steps carefully, and in order, you will have a greater chance of
ending up with a detector that actually works. Do not proceed to the next step until you have solved
any problems encountered in the current step. If you get stuck at any stage during the build, then
seek help in the Geotech forums before moving on. Do not simply populate the whole board;
discover it doesn't work (which will be the most likely result) and then post in the forums: “I've
built the Minipulse Plus, and it's not working. What's wrong?”, as you will receive little sympathy
from other Geotech members.
To reiterate:
Please follow the instructions step-by-step.
---------------------------------------------------------------------------------------------------------------------

I suspect you've been a bad boy and populated the whole board before testing.
haha I've been a bad boy too but its nice to know the steps are there and one can refer back to them if something does not work as expected. Rainig here today so its hard to make a video. In doors here is mostly all tiled floor with wire mesh under it except for my man cave but that's full of equipment and many sources of interference.

[6666]

Hmmm is U4 somehow running as a independent clock
how does this thing operate Davor ?

[6666]

Maybe I dont understand how a 4017 works,
the counters need to be reset at some point in the sequence,but if the 555 pulse is connected to the reset pin (15), (not the clock pin 14), the 4017 will reset the counters back to zero with each 555 pulse, how do the counters cycle if the 555 is continuously resetting the 4017 with each pulse.

[Silver Dollar]

There is a clock on the reset line to restart the sequence. You get a first pulse,
a double GB pulse then a second pulse then after a time the reset starts it all
over again...

See here, the blue pulses are the reset or restart pulses;

http://www.geotech1.com/forums/attachment.php?attachmentid=30826&d=1406921335