felezjoo PI(the best pulse induction metal detector that I made until now)

[useus]

do I have to modify some components to use an 8ohm 0.5w speaker?

[TufaN]

you do not need to replace any components at all. you can use

[sbalio1]

,..
https://www.youtube.com/watch?v=flJh...&feature=share

[sbalio1]

...
https://www.youtube.com/watch?v=Y88S...&feature=share

[sbalio1]

..
https://www.youtube.com/watch?v=gQ4X...&feature=share

[sbalio1]

it is better to use a sensitivity lower than 17

delay between 10 and 40 lose almost 10 cm on a plate of 20 cm copper and stainless steel .delay more than 40 loses a lot.
medium size coil better used delay between 30 and 40. for more stability
ground 1 = more stability and less detection ..... ground 10 = less stability and more detection ...... ground 1.2.3 = on moist soil or soil with many minerale like red soil .... ground 5.7.8 = in dry soil and less minerale
ground 9.10 = Rocky ground
integ is the reception delay .between 32 and 44 .... more than 44 = more noise with a few centimeters of ditection. 25 and 20 = more stability and less detection
Pulse between 150 and 200 with magnetic wires. More than 200 does nothing. With PVC wires more than 270 = more detection
speed .preferable use 6 or 7 .more than 7 = less stability. 5 = more stability and less detection
Iron reject = -15 with a signal of 100 or more. If it gives less than -15 it does not reject the iron well. If it gives more than -15 will reject another metal.
must use a plastic connector .the metal connector Affects the three digits.
Graphite shield does not work with this detector the ground wire gives continuous noise
you have to use a real cable rg58 or rg59 for stability in the ground.
Walk slowly to avoid false signals

[useus]

I built a new coil 0.9 ohm. Unfortunately I don't have an inductance meter and I built it with arduino.I am also waiting for the new pcb to arrive. From the calculations on the site coil32 should give me 350uh, but with arduino the value is between 380uh and 390uh. In your opinion is an acceptable inductance for a coil with an internal diameter of 20cm and an external diameter of 24.5cm?

[dbanner]

I built a new coil 0.9 ohm. Unfortunately I don't have an inductance meter and I built it with arduino.I am also waiting for the new pcb to arrive. From the calculations on the site coil32 should give me 350uh, but with arduino the value is between 380uh and 390uh. In your opinion is an acceptable inductance for a coil with an internal diameter of 20cm and an external diameter of 24.5cm?

Your coil looks excellent, and should work well. Measuring inductance is always a tricky thing. Try measuring a small inductor of known inductance(such as from an old radio set), something in the micro henries range, and see how far off the reading is. That would give you an indication of the margin of error. Better yet, you can purchase one of those component testers off of Ebay which seem to do the business pretty good. The M328 tester. It goes by other names too. It's an LCR and component tester.

[useus]

Your coil looks excellent, and should work well. Measuring inductance is always a tricky thing. Try measuring a small inductor of known inductance(such as from an old radio set), something in the micro henries range, and see how far off the reading is. That would give you an indication of the margin of error. Better yet, you can purchase one of those component testers off of Ebay which seem to do the business pretty good. The M328 tester. It goes by other names too. It's an LCR and component tester.

I finished assembling the electronics, the debug values are very close to 300 700 800 with this coil (296/698/796 are the best average values I obtained by adjusting frequency and pulse). I have no gold to see if it detects it :P but a 1 euro coin takes it at 25cm

[useus]

I am very happy with the operation of the metal detector, air test playing with the parameters finds 1 euro at 34cm, 0.2 grams about small gold medal 5cm. When I get the bms for the batteries immediately field tests!

[Altair]

Useus,
very good job!
I am wonder how you have wound your beautiful coil; could you explain, please?

[useus]

Useus,
very good job!
I am wonder how you have wound your beautiful coil; could you explain, please?

thanks!!

30 turns SWG22 enamelled copper wire internal diameter 20cm, I applied a good quality scotch over a board to hold the wire during the winding, then with a plastic circle of 20cm I started clockwise and I wrapped very patiently. finished wrapping I passed the hot glue as you see in the picture always very patiently holding the flat wire with two plates and bench clamps. in the end I wrapped the wrapping in the upper part and poured the epoxy resin just enough to cover the coil. finally I filled it all with polyurethane foam. For the base I used polystyrene, for the edges and the lid the polypropylene

[useus]

some photos, built on my size. fully diy. As a telescopic rod I used a damaged carbon fishing rod. I have to finish covering the top of the plate, reinforce the bracket and complete the power circuit (3x18650 + BMS + Boost converter) but the bulk is done. Finally a nice cleaning

https://imgur.com/a/vhIubEI

[mushaba]

I dont know if the picture is misleading but it seems you ve got your 7805 placed wrong,does it work?

[useus]

I dont know if the picture is misleading but it seems you ve got your 7805 placed wrong,does it work?

you saw it wrong, it is positioned correctly and is fully functional