White's PI3000 re-build

[Octopulse]

how do you know that your R16 was in fact 5.6 ohms?

It still bothers me that someone counted 36 windings in the original coil(not the pulse diver 950).

Please, if you can, check your board to see if you have 150pF cap, 100k and 82k around CD4069 clock.

(It's written on the PI3000 schematic).

Both those resistors measure exactly 100K and 82K.....the capacitor is labelled 151 so that should be the 150pF cap.

[nickel_n]

Not very clear but it may help

[GeoMax]

all are in files.

Hi KT315,

the set of "PIDX pages" reassemble the Whites PI2000 model. I traced that and compared it with a "Whites PI2000" labeld schematic. My questions are now the following. Maybe someone knows the answer.

1) Were the PIDX pages issued by Whites Electronics? If not, does someone knows who published them?
2) If it is not published by Whites, has Whites Electronics copied this detector from someone else?
3) Was the PIDX dokument published before or after Whites launched their PI2000 detector? The year?

Unforunally there is no information in the whole document about the true developer of this detector and the cover page is missing as well.

[dbanner]

if you wrap a mono-loop with two wires at the same time 18 turns and then cut the coil open and count the individual conductors you will have 36.

Yes, but why wrap such a coil? Unless you require a well balanced centre tapped coil. I don't think parasitic C or even sheilding would be much of a consideration at a first sample @30uS

Maybe they were going for higher series resistance coil, but with relatively small inductance, anyways, that all.

[Altra]

if you wrap a mono-loop with two wires at the same time 18 turns and then cut the coil open and count the individual conductors you will have 36.

[dbanner]

all are in files.

This data gives between 29 and 32 turns app.

[Carl-NC]

If one was careless enough to short the IC charge pump when powered up (like being stupid and not replacing the plastic insulating piece that separates the back of the PCB to then shorting to something metallic like a battery pack)......could R16 burn because I took a look at the old charge pump and it looks bubbled. It has since been replaced with a new one. I also found some pictures of R16 before I did any updates and it is looking burnt. Obviously the problem continued after my updates and was there the whole time?? I guess I will know tomorrow when I replace R16 and then reconnect the coil wires. Stay tuned.

I see no relation between R16 and the charge pump. Assuming dbanner 's timing is correct then the coil is on for 30us with a drive voltage of 9V. I will assume the coil is 250uH and the total resistance (R16+coil+switch+etc) is about 7.5Ω. This makes the turn-on tau 33us, which is about the same as the pulse width. So the turn-on current will be a 1-tau exponential with a turn-off current of 0.75 amps. This is why there is a series resistor, to limit the peak current. Otherwise it will be over an amp. Total integrated power in R16 over the pulse period is about 0.22 watts so a 1/2W resistor should be sufficient.

Right now I see no red flags. Unless there is a coil problem then it should work.

[dbanner]

Lucar may have counted 36 turns and be correct. It could be 18t + 18t in parallel? The original ML Sovereign used this technique to lower the capacitance and resistance while maintaining the same inductance. Trust Bill Lhar's information.

Lucar is no idiot, besides, how in the world can anyone count to 36 with just 18 turns of wire in a mono-coil loop available to be counted. Nah, not possible.
I think it might be some leftover AF108 coils which were adapted by Whites UK.

[kt315]

[kt315]

[kt315]

I believe you counted them correctly. The assumption was that you were not an idiot.

Strangely enough, the AF108 circuit bore a close resemblance to the PI1000/2000/3000 circuit. That detector AF108 had a centre tapped coil.

Another clue is R17 on the PI1000/2000 circuit. It is 1K.

So it would be nice for somebody to measure their pi1000 coil(the older coils)

all are in files.

[dbanner]

The AF108 had the same coil, at least the housing looked the same. I am now suspecting 18+18 turns with a centre tap for the AF108.

[Altra]

Lucar may have counted 36 turns and be correct. It could be 18t + 18t in parallel? The original ML Sovereign used this technique to lower the capacitance and resistance while maintaining the same inductance. Trust Bill Lhar's information.

[GeoMax]

Hi DBanner

I asked the same question some time ago.... Here the answers I saved.


Coil specification for a Whites PI-1000 or PI-2000 or PI-3000 detector needed
02-27-2023, 11:22 PM
Hello,

does someone knows the inductions or specification of the mono coil for a White Treasuremaster PI-1000, PI-2000 or PI-3000 underwater metal detector?
In one of the schematic diagrams I found the information that the coil diameter is about 11 inch and has 18 turns. Is this correct?

thanks...



Info posts by ALTRA, Geotech Forum (date 28.02.2023):

My old notes show 200uH, 1.25 ohms. The original 11-inch coil had 18 or 19 turns. The inductance of 200uH is an actual measured value. Several different PI-1000 coils were measured that time.
Wire size, I think something like stranded tin #24 or #26 gauge with PVC insulation will work just fine. Avoid using magnet wire; litz wire would be a waste on this detector.
The cable to the detector was equivalent to RG58A/U stranded coax.

Source:
https://www.geotech1.com/forums/foru...etector-needed


Other Info to the coils

Whites PI3000 coil info.
Early ones before 1995 had open coil, they later became available with flat Pulse Diver 950 weighted loop.
Source: https://forum.kimbucktwo.com/whites-pi-3000-t27474.html

[dbanner]

I believe you counted them correctly. The assumption was that you were not an idiot.

Strangely enough, the AF108 circuit bore a close resemblance to the PI1000/2000/3000 circuit. That detector AF108 had a centre tapped coil.

Another clue is R17 on the PI1000/2000 circuit. It is 1K.

So it would be nice for somebody to measure their pi1000 coil(the older coils)