Minipulse Plus Rev My time has come!

[Qiaozhi]

I've just tested the way you describe at about 20 cm off ground,no signal except only above targets.

In that case the EFE seems to be working perfectly.

Sadly i dont have a ferrite pot core on my workshop,i do have a ferrite out of a laptop PS, a broken ferrite out of an iverter welder PS and a soft magnet.The first two are not detected at all.The soft magnet when i bring it near the coil no sound at all but when i take it away there is a little audio sound..I attach a photo below

[ATTACH]46266[/ATTACH]

Again, from your description, there doesn't appear to be any problem with ground response.

I don't think you have a problem with shielding in your ground conditions. If you were searching in wet grass without an electrostatic shield, then you might have some issues.

[mushaba]

If it "seems" to be reacting to the ground, then there's most likely some metal there (could be deep).

For sure there are lots of iron filings from grinding and lots of little pieces of metal..In the air tests i made i can detect a 0.1 gr lead weight i use in match fishing at about 5-6cm..It is supposed to be that sensitive?Sorry George might be a false alarm by me but i've never used a detector that sensitive.I only used Garrett GTI2500 and a Minelab Explorer SE in my hole life,but as they are VLFs i thought the response should be like them..In other air test in my workshop i detect a normal size soda can at about 70cm a gold coin at 28 cm(25 cm clear signal) my only worry here is not the MPP doesnt work but maybe i made something wrong with the coil.

The EFE only occurs when you wave the coil quickly from side to side. Try waving the coil in the air away from the ground, and if there's a signal at the end of each swing, the EFE is not working properly.

I've just tested the way you describe at about 20 cm off ground,no signal except only above targets..

You can also check EFE in an air test by waving a white board magnet across the coil a few inches away. Don't get too close or the material of the magnet will be detected. Air testing whether the detector reacts to ground can be done with a ferrite pot core. With default timings, the ferrite will not be detected.

Sadly i dont have a ferrite pot core on my workshop,i do have a ferrite out of a laptop PS, a broken ferrite out of an iverter welder PS and a soft magnet.The first two are not detected at all.The soft magnet when i bring it near the coil no sound at all but when i take it away there is a little audio sound..I attach a photo below

[Qiaozhi]

Calibrated to the instruction timmings,still interacts a lot with the ground,is there a way to see Earth Field Elimination canceling (except the EFE pulse width and delay pulse)???

If it "seems" to be reacting to the ground, then there's most likely some metal there (could be deep). The EFE only occurs when you wave the coil quickly from side to side. Try waving the coil in the air away from the ground, and if there's a signal at the end of each swing, the EFE is not working properly. You can also check EFE in an air test by waving a white board magnet across the coil a few inches away. Don't get too close or the material of the magnet will be detected. Air testing whether the detector reacts to ground can be done with a ferrite pot core. With default timings, the ferrite will not be detected.

[mushaba]

Calibrated to the instruction timmings,still interacts a lot with the ground,is there a way to see Earth Field Elimination canceling (except the EFE pulse width and delay pulse)???

[godigit1]

Thanks Qiaozhi,
I have two beach boards my intention is to keep one of them close to stock for use on the beach. Giong to turn the Ds I have into different tools.

I wasnt pitting the MPP against the TdI mearly Trying to say Im happy with the MPP and dont hesitate to grab it for a beach hunt over the Tdi.
For me its all about target recovery when I hunt I want to recover as many targets as possible good or bad. Mpp is faster for me recover more recent losses.
I know my hunts are guided by the laws of averages and really Ive figured every 100 peices of junk jewelry or right there I find one or two silver or gold finds.
For that !00 peices of Junk Im probably digging close to a thousand targets.
Its allabout the #s in a hunt yes experiance plays a huge roll I dont have to say that here really.
Ill just say I would rather dig foil and beavertails out of the park grass or the beach and small iron than to hunt for coins, soooo many peices of small odd shaped jewelry hit in the 35 to 40 area of a Fisher type disc scale its crazy. And soo many times have I kicked off a layer of dirt to have that small peice clean up from a garbage no vdi lock to a nice 52 and its a 1 gram blackhills gold maple leaf earing.
Ok Im going on but every detector is a different tool thats why experianced detectorists have a multitude of detectors not just beacuse its the next coolest thing.
Like we carpenters say you can have all the tool in the world Doesnt help you if you dont know how to use them. Choose the right tool for the job.

[mushaba]

Looking good Mushaba,

What kind of hunting do you actually want to do? Im getting mixed signals. Small iron will be unavoidable with most all coils. If you tune it out you will loose small gold as well. A fast coil is going to nail small iron all the harder.
The majority of my beach finds are in the sub 2 gram range. And I find allot of earings So many that I know what styles im not hitting due to detectability.
Where I can I hunt Beaches with a Higher Frequency (Gold Bug Pro Or G2 even a GM3). I can find earing backs and studs. With A Pi most of that is untouchable. But Im still hitting paper staples with a 12 inch dual field coil with stock MPP rev d Machine. Iron is very hard to get rid of and if you do you will surly loose small gold.

I will say this about the MPP that Ive used both it and my TDI on the beaches and I use the same dual field coil. That sure I punch way deeper with the Tdi but damn 3 feet for a can will wear you out after a while Plus The TDI is heavy. Hunts are 3 hours instead of 5 barely worth driving to the beach for. I love whites machines but why cant they get ergonimics right they just stay with that obnoxious box sticking out into your side forcing you to hold your arm at a funky angle to get the detector to not wear a hole in your side. Jusus Minelab is lightyears ahead just by turning the box verticle and rounding the corners. Pardon me square box fans .
The MPP hunts slower but is damn good at small targets within the first 1 foot of soil. And nickles at 12 + inches..
You dont have to keep remaking coils you can take a few wraps off one you allready made for experimenting. The other thing always over wrap and remove raps testing with your Lc meter you will probable see 15 to 25uh per wrap come off. You can dial your coil in to the inductance you want.

Hello godigit1.

Im not complaining about anything,my detector works GREAT,at this time the test made on my trashy iron-wise backyard as i say in previous post a lot of ironworks made here over the years leaving lots of iron of all sizes...Its detection range is exceptional (i will make a video with air tests) i say this because the same backyard i scanned with the gti2500 and lots of the small targets found with the MPP when the gti was allmost silent.Its a gold-coin machine and i like to keep it this way as it ment to be..Now about the kind of hunting,im new to all this,here all treasurehunters are looking for ww2 gold,gold coins etc.I will preffer a build in the future with ground balance and discrimination if possible..I just want my MPPtuned for small gold and to do that i should take it on a "clear" environment to test it and see its behavior...Also have Svens Mirage and KT's Delta Pulse Legend on hold..Also i ordered some CrossBow revC pcbs from jlpcb...

It is more likely that your detector is reacting to the ground due to the 8us delay. The MPP does not have a ground balance control, so you should keep the delay above 10us, and will probably need to increase that to 15us for hunting in the surf on the beach.

Hello George,at first thank you for designing a great detector and i dont know if you mind that i put your name on my MPPs front panel..I thought about the reaction with ground and i will follow ALL of your initial instructions about timmings.Also i should have started as the instructions said with a simple bundle mono coil but i didnt understand the hole shielding thing,so i tried the easiest,the 3dss that doesnt need shield.I will calibrate to the original timmings and i will get back with scope readings and photos.

Last to be said i know i was a GREAT GREAT pain in the *** for all of you and please accept my sincere apologies but believe it or not i've allready gained my piece of treasure and that is KNOLEDGE i did not have before,not saying now i have but im nothing like me on my first post..The MPP was a great school from me to begin working with detectors.I hope for all help and guidance from now on from all of you.

Feels like a "final" post but its not,i will try to make my MPP better,i will follow all advise and modifications made on site and im willing to help in anyway i can,only thing im asking is guidance because tons of great things are written in this forum but also imagine a rookie diggesting all this info,that is make my mind spinning like waltr said before.

[Qiaozhi]

I will say this about the MPP that Ive used both it and my TDI on the beaches and I use the same dual field coil. That sure I punch way deeper with the Tdi but damn 3 feet for a can will wear you out after a while Plus The TDI is heavy.

I'm not surprised that the TDI goes deeper than the MPP, as the TDI is a much more expensive commercial machine, and has a more powerful transmitter. However, the MPP REV-E should be deeper than the REV-D version when adjusted for the beach. In fact, it has comparable performance to Crossbow (an HH variant), which some people have claimed to be as deep as the TDI.

[Qiaozhi]

Done some testing on my backyard,a very trashy environment due to lots of ironwork done there.I should get it out in to a "clean" environment for field testing..The detector is very sensitive and i believe thats because my 3dss coil is unshielded.
Had to keep the coil at 10 cm above ground,gain at minimum threshold at almost minimum and delay early and narrow..The best delay with this setup is 8us (from end of tx pulse until negative curve comes to 0 at TP3). I attach 2 photos om my first find,i believe its a piece of rebar and the coil connector,a bnc T type were i can mount the damp resistor.
Your thoughts please

[ATTACH]46249[/ATTACH]
[ATTACH]46250[/ATTACH]
[ATTACH]46251[/ATTACH]

It is more likely that your detector is reacting to the ground due to the 8us delay. The MPP does not have a ground balance control, so you should keep the delay above 10us, and will probably need to increase that to 15us for hunting in the surf on the beach.

[godigit1]

Looking good Mushaba,

What kind of hunting do you actually want to do? Im getting mixed signals. Small iron will be unavoidable with most all coils. If you tune it out you will loose small gold as well. A fast coil is going to nail small iron all the harder.
The majority of my beach finds are in the sub 2 gram range. And I find allot of earings So many that I know what styles im not hitting due to detectability.
Where I can I hunt Beaches with a Higher Frequency (Gold Bug Pro Or G2 even a GM3). I can find earing backs and studs. With A Pi most of that is untouchable. But Im still hitting paper staples with a 12 inch dual field coil with stock MPP rev d Machine. Iron is very hard to get rid of and if you do you will surly loose small gold.

I will say this about the MPP that Ive used both it and my TDI on the beaches and I use the same dual field coil. That sure I punch way deeper with the Tdi but damn 3 feet for a can will wear you out after a while Plus The TDI is heavy. Hunts are 3 hours instead of 5 barely worth driving to the beach for. I love whites machines but why cant they get ergonimics right they just stay with that obnoxious box sticking out into your side forcing you to hold your arm at a funky angle to get the detector to not wear a hole in your side. Jusus Minelab is lightyears ahead just by turning the box verticle and rounding the corners. Pardon me square box fans .
The MPP hunts slower but is damn good at small targets within the first 1 foot of soil. And nickles at 12 + inches..
You dont have to keep remaking coils you can take a few wraps off one you allready made for experimenting. The other thing always over wrap and remove raps testing with your Lc meter you will probable see 15 to 25uh per wrap come off. You can dial your coil in to the inductance you want.

[mushaba]

What about the sensitivity issue?Should I go bigger on coil to reject smaller items since we cannot reject iron?Also is there a possibility EFE to not work as should because of higher operating frequency?

[waltr]

You found something. I just call this 'a rusty thing' and always finds lots of them.
With actual field testing you get to tweak settings to find what works best.
Then is learning what different targets sounds like for a better guess of what they might be.

Interesting way to do the damping R.

[mushaba]

Done some testing on my backyard,a very trashy environment due to lots of ironwork done there.I should get it out in to a "clean" environment for field testing..The detector is very sensitive and i believe thats because my 3dss coil is unshielded.Had to keep the coil at 10 cm above ground,gain at minimum threshold at almost minimum and delay early and narrow..The best delay with this setup is 8us (from end of tx pulse until negative curve comes to 0 at TP3). I attach 2 photos om my first find,i believe its a piece of rebar and the coil connector,a bnc T type were i can mount the damp resistor.
Your thoughts please

[waltr]

Looks good.
Do post pic of your first find.

[mushaba]

Loading 95% but still not finished...Remains coil critical damping on the detector and possibly another front panel i messed up..A little sneak peek please judge with generocity!



Battery compartment with 3 x 18650 batteries with charging connector...Want to put a BMS inside for correct charging



Didnt have in mind the OD of the pot knobs...I hope the designer doesnt mind putting his name on it..



The build so far. A headphone connector must be placed with a pot....I hope tommorow i will have my fisrt findings!!

[green]

Made an error measuring SRF with shield again. Did same thing awhile back, keep forgetting correct procedure. Connected shield lead of test coil to circuit common where it is normally connected. Should have connected it to one of the test coil leads. Flat radial_2.87MHz no shield, 2.475MHz shield to circuit common, 1.74MHz(2mm craft foam spacing each side between coil and graphite shield)1.9MHz(5mm spacing)with shield connected to one of the test coil leads.