Minipulse Plus Rev My time has come!

[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]

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)???

[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]

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]

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]

Ok George

Ive just came back from a field near my house,an agricaltural field sand soiled,there i realise how iron-trashy my backyard is..The detector was as suposed to be,i found some pieces of fence wire and other stuff.Came back to workshop placed detector on the air test position,calibrated the timmings frequency at 1KHZ and the first sample not before 10us and took scope readings from the Rx Preamp..First stage all looking good (to my eyes) pin2 as attached photo,pin3 at zero,pin 1 as photo (same with pin5) but at the output pin7 i think there is lot of noise,should be like that???No electrical interference near the detector

[Qiaozhi]

That looks like external noise pickup. Try changing the orientation of the coil (horizontal and vertical) and see if anything changes.

[mushaba]

That looks like external noise pickup. Try changing the orientation of the coil (horizontal and vertical) and see if anything changes.

No change George..I dont have a spare NE5532 to see if there is a problem with the ic..If is an external noise pickup shouldnt show on input pin?

[mushaba]

.

[godigit1]

HEY Mushaba,
Going back a little bit in this thread I found this vid complete with a Scope set up and lazy mans math A online calc for checking L without a Lc meter.
Its a way to double check ours meters as well .https://www.youtube.com/watch?v=RhS8m38ef0Y

[green]

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.

I think it was 6666 suggested using a fridge magnet. I tried one awhile back and thought it worked good, not detectable and would cause a signal when pulled away from coil. Tried one this morning, not detectable but didn't cause a signal when pulled away from coil. Tried a craft ceramic(ferrite)magnet. Thinking ferrite core and ceramic magnet not detectable as a Tx off target, lot less signal than ground(maybe none except for a shift right when coil is decaying). Target distance was adjusted for 200mV change when Tx on. Last picture is sweeping the magnet across the coil a few times. Wondering what your white board magnet is made of. Would your ferrite pot core look closer to a ground signal decay than the one I used? They would look similar to ground with a VLF.

[mushaba]

Hello green.At left of the photo the waveform is preamp out?Is it from a MPP?

[mushaba]

HEY Mushaba,
Going back a little bit in this thread I found this vid complete with a Scope set up and lazy mans math A online calc for checking L without a Lc meter.
Its a way to double check ours meters as well .https://www.youtube.com/watch?v=RhS8m38ef0Y

Hello godigit1,a function generator is on my wish list.Still a very good way,with a pulse can easily produced with a simple 555.Will try it soon .

[mushaba]

Question of the day,how does the EFE work?I imagine it takes a sample of the field,then invert it and substract it from original sample?To achieve that it should drive three op-amps one with sample another to produce the inverted sample and a third to substract them?

[green]

Hello green.At left of the photo the waveform is preamp out?Is it from a MPP?

No, preamp out from my target response tester. Don't have a MPP.