فلزیاب تفکیک دار Chance

ممنون کوروش جان. داغ کردن 7805 در این مدار کمی عجیب به نظر میاد! چون قسمت قدرتی پالس که اصلا از 5 ولت استفاده نمیکنه! قطعا باز یک اشکال دیگه در طراحی هست بهرحال با گذاشتن هیت سینک روی 7805 این مساله تا حدودی قابل رفعه.
کوروش جان من به شدت درگیر ردیاب جدید هستم و فکر میکنم تا 1 ماه طول میکشه!

دیدم دوستان سخت تلاش میکنن گفتم یه کمکی بکنم بد نیست .
این لینک روسی که میزارم بهترین کوئیلی هست که جواب بیشتری داده و همه راضی هستن و اندی هم تایید کرده .

.http://www.metdet.ru/Sensor_K1.htm

داداش رضا وقتی اسمتو دیدم که پست دادی تنم لرزید - گفتم لابد یه سند دیگه واسه محکوم کردن چنس آوردین

دوستان انجمن فلزجوو اگه داداش رضا و حمید جان قدرتشونو واسه این دستگاه بزارن از نمونه خارجی 100% بهتر خواهد بود

داداش رضا اطلاعات چشمگیری دارن

واقعا ازتون ممنونم رضا جان که به کمکمون اومدی- انرژی فوق العاده ای بهم دادی -

تشکر داداش

تشکر

مشکل اونا تو پایداری بالانسه که وقتی نوع و جنس خاک عوض میشه به خطا بار رو میزنه . من دشمن کسی نیستم و فقط دوست دارم شما به نتیجه برسین .

این فایلو اندی به رفیقاش داده برا تئوری کار دستگاه .

As the author of this project say, Chance is build on the basis on US5506506 patent Smiley
You can download this PDF and check the schematics and PCB files

دوستان یکسری عکس از دستگاه های ساخته شده امیدوارم کمکتون کنه .

ادامه تصاویر .......

یکسری اطلاعات که میتونین با گوگل ترجمش کنید مشکلات و راه حل های مهم در ساخت این دستگاه در سایت روسی و ژئوتگ .


I finally get Chance working. After soldering all connections second time I installed

Hammerhead coil and everything start work. Guard interval was set to 25.
Coil spec: 0.566 mH, wire thikness=0.4, number of turns = 26.
I still need to try original basket coil.
Anyway "constant tone" is now gone away.









Hi, I've built a Chance PI and it's not working. The buttons work OK but when I turn it on I

only get a continuos sound. The coil it's not working, doesnt react to a metal piece, only

constant sound......

Any help would be appreciated

http://www.youtube.com/watch?v=ZHU2PPuNosg


Chance should work (somehow) even whit 6 AA cells, but use 12V supply first. If problem

persist, try this "defectation" using just DMM:

First measure positive voltage at pin 7 of U5 (OP37) and negative at pin 4, should be

somewhat lower, volt or so, than supply voltage. If negative voltage is absent, close to 0

volts, check circuit around U1, part orientation etc, if necessary replace 7660.Also check

surrounding parts around Q4 (inverter disable). Without -V power stage will not work either.

Also, if you have slightly lower voltages present at both pins, remove U5 and try again

(maybe U5 is damaged, then check orientation and integrity of protecting diodes D7&D8 and

replace chip.
If this is ok, check +5V (obviously good, MCU working) at pin8 U6, and also reference at pin

1 U6, should be about 4.1V. If not, check parts around U3, TL431.If this is OK, problem is

probably in the power stage whit MOSFETS. Measure current consumption whit and without coil,

should be around 100ma whit coil, and, say, around 20 without. If it differs slightly, too

high without coil, or too low when coil is connected, check all parts in power stage, around

Q 1,2,3,5,6,9,D1, 4,5,6, orientation, resistor values etc. Will be helpful to have scope at

this point. Good luck.









As I recall from testing, any selection of Iron Mask does somewhat degrade small gold

detection. However the tests I have done are air tests on top of my pool table in the

basement of my house, being careful not to have metal within 3 feet of the coil top and

bottom and more than 2 feet from the coil edges. All flourescent lights turned off and all

TVs and radios off. In fact having my old CRT TV in the basement turned on prevents the

detector from operating properly. That said, the performance outside and away from

civilization and it's electromagnetic signature may very well improve.

The settings of the Chance parameters for my tests are: Barrier - 1, Volume - 3, Guard

interval - 17, Iron Mask - NO. I try to keep my supply voltage at 12 volts nominal from Nimh

rechargeable cells. Max current draw with display lit is about 115 ma and about 90 ma

without display lit.

A friend of mine has an 18 grain gold nugget he will lend me for further tests and I'll post

the results here as soon as possible. I'm hopeful to detect this natural nugget at > 4

inches using the 8" coil...we'll see.

I'll also test the effects of Iron Mask 1 on detection distance this next week and let you

know. Since the Iron Mask function is driven by time I believe any large piece of metal has

the potential to present as Iron or be screened out by the masking. Wouldn't it be a shame

to miss a golf ball size nugget because the Iron Mask screened it out? The discrimination

does an OK job on targets of similar small sizes with gold consistently showing up on the

left of the scale. Silver consistently shows up near the right end of the scale and Iron

always at the right end. Bigger slower targets go towards the right end.











I have been building/optimizing the Chance for about two years. Started with software

version 0.8.4 and currently running 1.2.1. The software much improved the performance.

Recommend the axial lead 220uh choke be avoided and replaced with one capable of greater

current handling capacity. I wound my chokes on toroids using 26 awg enameled copper wire.

Also the author's original basket weave coil is OK for coins and jewelry but not for

fine/small gold flakes. I am using a 'spider wound' 8" coil for small gold detection

shielded with graphite al la Satdaveuk process outlined in the COILS forum with a heading of

Graphite Shielding.

All schematics of the Chance detector are in detached form but the website is pretty clear.

If you have Silverdog's recent boards you can ignore the Mods required for the older

production boards. I have done one of each.

I use the OP37 opamp as it has superior parameters to the NE5534.

Regards,










I'm reposting this from the Chance PI Problem thread because I think it is more appropriate

here. This isn't so much about a Chance problem as it is about optimization and improvement

of the Chance PI detector and the associated coil.

I've been away from the forum for a while but have been doing more optimization on my Chance

PI. The current coil I am using is 8" dia wound in the previously discussed 'spider'

configuration on a .091" thick 1.050" wide polycarbonate form machined with 37 slots .400"

deep on the inside and outside rims. The wire I am using is Teflon insulated stranded,

silver plated, #26 AWG, .040" O.D. and after extensive testing the optimum inductance for

small gold detection with my electronics is 330 to 340uh and about 2.0 ohms resistance. On

this coil form this is achieved with 32 turns wound in spider coil fashion.

I have also eliminated the coax feed to the coil as it contributes too much capacitance thus

slowing the coil down. Instead I use a continuation of the coil wires twisted at a rate of 3

twists per inch. This I will sheath with heat shrink. The low capacitance coil created in

this way will run at a Guard Interval setting of 17 on my Chance PI. My previous best was a

setting of 19. This 8" configuration will detect a 1cm square of .001" thick aluminum foil

at 4" in air. It will also detect a 10.5 grain piece of dental gold at 4" and an 8.4 grain

piece at 2". This will also detect my 10K gold ring at 12" in air.

I am running this coil without shielding at this point until I can determine if it is truly

necessary. In thinking about this specific coil winding configuration I wonder if it

somewhat self shields when the outermost winding end is connected to system ground. This is

because the successive windings are wound over and around all previous windings. I am also

looking at the possible increase in sensitivity if the outermost winding end is connected

instead to the high side of the system in/out. In that case graphite shielding in the range

of 2000 ohms per inch may be required.




After doing a bit of reading it appears that the 390 resistor is only an adjunct to the

active damping provided by the IRF9640 mosfet. I wonder if there is any point to trying to

optimize the 390 ohm damping resistor? It still seems that an optimized value might benefit

detection of small gold in the low microsecond ranges. Has anyone used another value for the

damping resistor in this detector?






Please insure that you are using the latest modifications to the Chance as the KP505 was

replaced with a 2SC945 transistor. This was necessary in order for the unit to operate

properly with the version 1.2.1 software.


The diode HER208 is not going to get here. I could maybe replace this by Ultrafast diode

UF4007?
Where can I download the PCP layout. Best known as SPRINT layout. On the site there is the

http://fandy.hut2.ru/Chance.htm programs and a pdf. Or did I overlooked something?
Thank you!

The UF4007 diode has the same voltage rating but 1/2 of the current ratings of the HER 208.

It does have 1/2 of the capacitance which should be a benefit to performance if it will

stand up to the demands of your coil/detector electronics.

I'd give it a try, good luck!


I have the Ultrafast diode MUR 240 used (CASE 59, 400V, 2A). I'm curious to see if it works

....
All the best,

رضا جان ، تشکر دوست عزیز ، از این همه زحمت

رضا جان ممنون داداش -

میدونستم با اطلاعات شما این دستگاه بهتر میشه

تشکر عزیز