CHANCE Pcb's Finally Here

[bo198673]

Need to purchase CHANCE PI, any person to sell can contact me [email protected]

[bo198673]

Need to purchase CHANCE PI, any person to sell can contact me [email protected]

[kt315]

Your average detector from the shop will do a lot better.

golden words... maybe a time to begin new project there... I can ask Konstantin Saveljev to deliver PCB and chip for SPEKTR M1036 if you need about...

http://md4all.ru/index.php?showforum=24

[joop]

Did anyone do a field test with this detector yet? I have only read about air-tests on this forum. I have taken it to a field yesterday. Results seem a little disappointing.

Fields I visit tend to have a lot of iron. The Chance detector goes nuts on these fields, I keep on digging the somewhat larger iron objects. With iron mask set at 3, the detector is a lot quieter, but it misses copper coins in this mode.

Have been playing with the guard interval, does not seem to help.

Also, depth is about 15 cm for a copper coin. Your average detector from the shop will do a lot better.

Can anyone share their experience please?

[mickstv]

Hi All, I just finished making the chance PI and it's running firmware ver 1.2.1 it seems to be functioning correctly. I did the mods replacing Q2 and changing R9 but I did leave out D9 which normally would be located in parallel with R25 470k. So D9 doesn't seem to serve any purpose.

Other changes I did where the replacement of D4 and D6 they are now BYW96e because I didn't have access to the originals. Also I used BC639 and BC640 transistors in place of the ones listed.


The coil I used for testing was one half of a DD coil which is about 8" diameter and about 27 turns of magnet wire then electrical tape over it and a layer of foil then another layer of electrical tape. The coil lead is about 6ft of 75 ohm TV cable because that's what I had on hand.

Testing in my backyard I was able to detect an Australian 20c coin at between 30-35cm and a 1/2gram lead sinker at between 10-15cm. That was with the barrier set at 1.

Next will be testing out of town away from interference.




Mick

[smity]

question

dear tepco
my coil is tight.
first you need to know, my circuit is not exact chance circuit,it is a mod.
software is my own , on the otherhand right now R13 is 1K , ıf I use 390 R it gets our of saturation much more later.

with 390R at R13 monocoil construction , decay starats around 8us
but with this coil starts at 22us with 1k damping.

Please write more detail about their firmware and a modified scheme. Thank you in advance.

[selim]

change software 1.20 test video

http://www.youtube.com/watch?v=THM6_DXe9Ww

[joop]

I have built the default search coil today. I have used 0.4mm wire, did not have any 0.8 lying around. The coil has an inductance of 360 microHenry and a resistance of about 3 Ohms. Will be testing Silverdog's kit later this week.

[Tepco]

I have scope pics, will send it to you

[okantex]

dear friend,
yes this russian monocoil is a kind of monocoil , I call it basket coil,
because generally round pi coils are called mono,like used in delta pulse and other.

with 390 R damping resistor,
mono 8us
basket 29us
with 1k damping
basket 21us are my end out saturation , btw I do not have scope, just get this reading with LCD and software.
do you have scope
can you show me scope pictures of different metal with this coils.
does the curve change when considered by mono coils.

[Tepco]

I was completely unaware that your circuit is modified. Also, i'm not sure what you refer as a "monocoil", some other coil design perhaps? This on picture looks like original Russian monocoil. Still, whit this coil 22uS is way too slow and 1K to high, but still looks like good value (if time is increased when changed to 390R). It seems to me that something in the circuit increase total capacitance. If your power stage is similar to original, first check D4 and D6, using slow "ordinary" diodes (like 1N400x) instead of HER or FUF types can produce similar effect.

[okantex]

dear tepco
my coil is tight.
first you need to know, my circuit is not exact chance circuit,it is a mod.
software is my own , on the otherhand right now R13 is 1K , ıf I use 390 R it gets our of saturation much more later.

with 390R at R13 monocoil construction , decay starats around 8us
but with this coil starts at 22us with 1k damping.

[Tepco]

This "original" coil is not especially fast, built and measured to specifications, will provide ca. 13uS when amp goes out of saturation. And detector samples after 17uS. Most probable cause of problem whit your coil is that it is not built "stiff" enough, you should flatten and tighten windings on coil former. This way, you probably have more wire length and more inductance, and this will slow down the coil. If you use other (faster) monocoil, try to adjust (decrease in value) R13, to "overdump" the coil, so detector can see exactly right part of waveform when expected.

[okantex]

dear friends
excuse for late photo attachment
sizes are same as original andy_f 's coil.I got drawing form his site and made mould.

all wiring is in clockwise direction.

when I use mono coil my delay starts at 8 us ,
but with this coil it starts at 22us

btw I calculate and got result as 8 us but It may be wrong.
on the other hand whatever the timing unit is not important.
my op finishes saturation 3 time late than mono coil assembly.

regards
Okantex

[Legaucho]

Q2 is wrong on the pcb, S is ground, G goes to R3, D goes to Q1 For 2sc945 see pins in picture - Emitter to ground, Collector to Q1, base to R3

Hey Silverdog

Silverdog thank you, I would make the correction as soon as I get a free moment. Again thank you for your help. PCBs that you provide is truly professional quality.

Best regards