CHANCE Pcb's Finally Here

[silverdog]

Chance PI

If you install google toolbar it will translate each page as you view it

The three jumpers should be linked, as should a jumper around C4, this links 2 ground planes underneath

good luck

Silverdog

[mario]

Silverdog, I received the Chance PI board and parts from you and the board looks great! I am wondering if anyone on this forum can point me to a site that has construction information and details. It appears the there are 3 wire jumpers to be soldered onto the board near the microprocessor. Can anyone confirm this?

Also does anyone have coil build information for this PI, i.e. coil inductance and resistance specifications? Joe Rogowski's tutorial on this site, "Making a Fast Pulse Induction Mono Coil" is a great help in coil design. At the moment I am plannning on building both 6" and 8" 'fast' spidercoils for the purpose of small nugget detection.

Toward that end I am considering changing the IRF9640 mosfets out to much lower (Coss) capacitance units in order to keep most of the speed inherent in the spidercoil design. I am looking at using the Fairchild FQD5P20 mosfet as it has only 75pf versus 370pf for the IRF9640. My concern is the device dissipation for the FQU5P20 is at best about 1/3 that of the IRF9640 so heat sinking will definitely be included. Even so I think the mosfet can handle pulse currents up to 14 amps dependent on duty cycle and repetition rate.

I appreciate any assistance you and the other members can provide in this effort.

Regards,

Dan

Coil specs, connected to X1:

L = 400 uH , R = 1.7 Ohm.


Has any one built a working unit yet?

The board has an ISP header for programing the chip. How cool is that?!?

I also find it interesting that the atmega's DAC is relegated to battery functions, while offloading the more important processing to Microchip's MCP3201 instead.

Still, how is this design based off Minelab Pi tech? I see 1 channel for the signal: OC1A? Another channel (OC1B) for sound, which would explain the use of that odd crystal.

I personally like rotary encoders instead of switches, but Andy is really pin constrained with the atmega8. Then again, the next step up would be a 40 pin atmega, which would be overkill. A drop-in replacement would be the atmega328p, easily quadrupling his memory and interrupts with very little code modifications.

He's able to fit his program within the 8k restrictions and is awesome. He probably writes in assembly.


Interesting and all very cool....

[baum7154]

Thanks for the info. Now I'll find a russian translation on the web and really make some progress. It does show 3 jumpers on one of the drawings on Andy's site.

[silverdog]

Chance PI

Chance author andy_f has many details on his site http://fandy.vov.ru/Chance.htm

[baum7154]

Chance PI Build Instructions

Silverdog, I received the Chance PI board and parts from you and the board looks great! I am wondering if anyone on this forum can point me to a site that has construction information and details. It appears the there are 3 wire jumpers to be soldered onto the board near the microprocessor. Can anyone confirm this?

Also does anyone have coil build information for this PI, i.e. coil inductance and resistance specifications? Joe Rogowski's tutorial on this site, "Making a Fast Pulse Induction Mono Coil" is a great help in coil design. At the moment I am plannning on building both 6" and 8" 'fast' spidercoils for the purpose of small nugget detection.

Toward that end I am considering changing the IRF9640 mosfets out to much lower (Coss) capacitance units in order to keep most of the speed inherent in the spidercoil design. I am looking at using the Fairchild FQD5P20 mosfet as it has only 75pf versus 370pf for the IRF9640. My concern is the device dissipation for the FQU5P20 is at best about 1/3 that of the IRF9640 so heat sinking will definitely be included. Even so I think the mosfet can handle pulse currents up to 14 amps dependent on duty cycle and repetition rate.

I appreciate any assistance you and the other members can provide in this effort.

Regards,

Dan

[Legaucho]

Order Delivery

Hi all,

I receive todaye from silverdog my Chance PCB. Quick delivery and very good quality.

Many thanks to silverdog.

[asguard]

New CHANCE boards are here and working !!
..................

Hi Silverdog,

Can you mention who/where you get your boards manufactured, good job and looks like the price might be right. I require some with silkscreen etc. for other projects.

Cheers

[Legaucho]

Chance Order to SilverDog

I spent this morning an order for 1 x CHANCE + Atmega8 . Now I am waiting the arrival of this command to begin execution. Regards

[Mudflap]

Good news

That is good to hear!! Don't want to have to set up to program the Atmega. Had enough of that with the z80s and 6502s Can't wait for the kit!!

[silverdog]

That is bare wire, it goes around the cap, thru a pcb hole on each side and is soldered undeneath, used above I believe to join 2 ground areas together. Not required on my 2 sided boards but there as they are in ANDY_F's original design

[taliesin]

CHANCE problems

I have been working on mine this week and along with Jakub have noticed missing grounds etc...
I fear I may have made a mistake on these, although I am still a bit confused
The light blue layer in andy_f chance.pdf I thought was a solder mask and appears to be a top copper layer - hopefuly we can still use these boards with some jumpers as a test
If a top layer ground is also required how is the one working shown below ? I guess not using Andy_F board layout ?
If a copper top layer is used, I guess it is ok to use thru hole plating on every hole still ?

My apologies for anyone with one of these boards - lets work together and sort these jumpers wires out so we can get a working unit
I promise anyone who has purchased a board, once sorted and a new layout agreed, and if CHANCE works ok, I will get new boards made and
you can have a free replacement - I would have to ask for the $4 postage though

Silverdog

what is that wrapped around that large cap ?

[silverdog]

New CHANCE boards are here and working !!

I have added the boards to my shop, in the kit section I have also added the board with a preprogrammed Atmega, should you not have the ability to do your own. Full kits will be added in a few days.

A few more components have been added as well

www.silverdog.co.uk

regards


Silverdog

[BillBert]

CHANCE problems

I have been working on mine this week and along with Jakub have noticed missing grounds etc...
I fear I may have made a mistake on these, although I am still a bit confused
The light blue layer in andy_f chance.pdf I thought was a solder mask and appears to be a top copper layer - hopefuly we can still use these boards with some jumpers as a test
If a top layer ground is also required how is the one working shown below ? I guess not using Andy_F board layout ?
If a copper top layer is used, I guess it is ok to use thru hole plating on every hole still ?

My apologies for anyone with one of these boards - lets work together and sort these jumpers wires out so we can get a working unit
I promise anyone who has purchased a board, once sorted and a new layout agreed, and if CHANCE works ok, I will get new boards made and
you can have a free replacement - I would have to ask for the $4 postage though

Silverdog

Silverdog, Any updates on when the new boards will be available? Thanks.

[geminis74]

just started

[geminis74]

with the bridges I do not work.
may be that some component is damaged?
now I have no time, if you get it to work, I'll put here