White's PI3000 re-build

[kt315]

[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.

[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]

all are in files.

This data gives between 29 and 32 turns app.

[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]

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.

[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.

[nickel_n]

Not very clear but it may help

[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.

[Octopulse]

Well I am happy to report that the PI3000 is up and running and out of intensive care.....R16 is now a "happy" resistor. Ran the detector for over an hour and R16 (0.6W 5R6) was cool to the touch.

Initial tests on my gold ring were better than I was expecting....18K average size wedding band.

Thanks to everyone that contributed to the thread......it's good see another White's detector that should have a good deal of life left in her.

6 x new capacitors
1 x new charge pump (rated to 12v)
1 x new diode
1 x new resistor
1 x new 9V snap connector

All other IC's, resistors, transistors and diodes all checked and tested good. Hopefully the other non-electrolytic caps should be good.

[kt315]

can you send me pics of the board in high resolution? my email [email protected]
i have PI1000 pics sent on a request from a geotecher and i see big similarity with yours one. just for an archive.

tia

[kt315]

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.

hi geo

i am just taken files from the forum, keeping, and put them back later, on an occasion, but i do not keep authors names. just sometimes but not always.

pleasure

[dbanner]

Well I am happy to report that the PI3000 is up and running and out of intensive care.....R16 is now a "happy" resistor. Ran the detector for over an hour and R16 (0.6W 5R6) was cool to the touch.

Initial tests on my gold ring were better than I was expecting....18K average size wedding band.

Thanks to everyone that contributed to the thread......it's good see another White's detector that should have a good deal of life left in her.

6 x new capacitors
1 x new charge pump (rated to 12v)
1 x new diode
1 x new resistor
1 x new 9V snap connector

All other IC's, resistors, transistors and diodes all checked and tested good. Hopefully the other non-electrolytic caps should be good.

Great! Happy hunting.

“I love the smell of napalm in the morning. It smells like victory”

I just love that movie.

[GeoMax]

hi geo

i am just taken files from the forum, keeping, and put them back later, on an occasion, but i do not keep authors names. just sometimes but not always.

pleasure

Hi kt315,

okay... I do the same. I saved the PIDX files somewhere in the year 2002 already. There was also an actual picture of the detector that time. The detector was built by C.Pruysers, also a member in this forum. I had in mind to contact and ask him about this detector but he was seen online last time about 20 ago. Anyway, here is an actual picture of the detector he made that time. The resolution is not great, but you can identify the detector as the "PIDX detector".


The info saved together with the image was this.... "Detector Name PIDX (Picture_5 built by C.Pruysers (11-11-2002))"

[kt315]

this part of board of PI1000 with R16, pics sent me by Pete M. on his pcb he deleted marking of Whites so ID number is absent, in assumption.