chance pi build

[baum7154]

dantech,

Still 390 might not be optimum for that coil as it is possible to have too little resistance for most efficient impedance match and therefore quickest energy transfer out of the coil. There is a somewhat narrow range of resistance for optimum coil damping. I would increase resistance over 390 ohms until you just begin to see ringing appear and then slightly lower it just until it is gone. This is the point called 'Critical Damping'.

Regards,

Dan

[dantech]

Any report from field about v165?

[dantech]

http://chomikuj.pl/dantech/Chance+PI

The latest v169 (and probably last at all) for ATmega8

v300 is first compilation for ATmega328P.
Because of lack of flash memory in the ATmega8 I have ported the code for ATmega328P (32kb flash ram). The price of both controllers is the same but flash memory is 4x bigger. Both ones have the same pinout.

Every software will stop after 50 runs. Reflash is necessary. This is protection against commercial use

[baum7154]

Dantech,

Thanks for the update.
Sorry I have not been able to reply on field performance as I have to put a programming setup together for the Atmega chips. Are there any other changes in the V169 besides limiting its turn-ons to 50 runs? This is a very low number and will be a nuisance for CHANCE users in the future. On just a two week trip afield I could easily exceed 50 runs and have to reprogram the Atmega. I do however like the idea of the 32kb flash ram for future enhancements. Thanks for your efforts on the firmware and I look forward to using the latest version.

Regards,

Dan

[dantech]

There is a few code improvements and simplification above v165. 50 runs is enough but I shall take into account 100 runs in the future releases.
Do not affraid 50 runs limit in the field. There is runs counter at start.


BTW. The latest stability tests give R9=470 ohm

[baum7154]

Dantech,

Have you tried to detect a 6mm square of soda can side wall yet? If it isn't detected try a 1cm square of soda can side wall. These targets simulate small pieces of gold.

Good info on the 470 ohm R1 change. I think it could go even higher as the original coil has a very fast self resonant frequency without the electrostatic shield necessary for work in the field at short sample delays. However because of the original coils broad and flat geometry, the addition of the shield slows the coil down significantly with the added distributed capacitance.

Dan

[dantech]

Not R1.
R9=470 near Q6. Sharp edges are critical in that circuit to make VDI stable and independent from signal strenght.

I did special release generating main pulses only (for ATmega8 to see coil ringing).
For dedicated coil R13=390 ohm and one is great. Ringing is visible above 500 ohm

I still do not have another coil than dedicated one.

Would you give me the size of your "racetrace" coil and winding scheme?

[baum7154]

Dantech,

Sorry, R13 my mistake going from memory.


All of the posts in the Chance PI Coil thread in the COILS forum related to the Race Track 3DSS coil are as follows:

'Since this build has been going on for quite a while my posts on its construction are spread across several pages in this thread. Below are the post numbers in this thread that pertain to this build.

POST NUMBERS: 126, 134, 136, 138, 139, 142, 169, 173, 177, 179, 215, 216, 228, 229, 232, 236, 254, 255, 256, 257, 258, 262, 263.

Hopefully this will help to find construction details quickly.

Dan

Additionally the coil is 12.5" long by 4" wide to its midpoint. The coil is wound in the same fashion as the round version in the same thread on a slotted coil form having 37 slots on the outside perimeter and 37 slots on the inner perimeter but staggered to the midpoints of the outer slots...see photos. The coil measures 328uh in inductance.

Are you able to see the 1cm square aluminum from the side of a soft drink can with your original coil?

Dan

[baum7154]

Dantech,

What AVR programmer are you using for the Atmega8? I have the LCsoft Studio V2.0 USB to 10 pin hardware shown in post #91 of this thread. I am looking for compatible software for this device to program ATmega8 & ATmega328P chips.

Thanks,

Dan

[dantech]

The one is called USB ASP and it is compatible with AVR dude (controlled by console). GUI frontend is called AVR8-burn-O-mat. I use linux everywhere I can (I hate Microsh*t).

I saw AVR ASP on aliexpress for $3-4. This is quite popular programmer in europe and it is available locally

[reptooyep]

Dantech,

What AVR programmer are you using for the Atmega8? I have the LCsoft Studio V2.0 USB to 10 pin hardware shown in post #91 of this thread. I am looking for compatible software for this device to program ATmega8 & ATmega328P chips.

Thanks,

Dan

Hi Dan,
Your programmer is a clone of USBASP. So, you can use any software you want :
AVRDUDESS
EXTREME BURNER
ARDUINO (you can programm standalone chips with arduino software by Ctrl+Shift+u)
You can also use avrdude by command lines such as ; avrdude -c usbasp -p m328p -u -U flash:w:yourfirmware.hex

Regards

[baum7154]

Thanks reptooyep,

I would like to have software compatible with my personal iMac V10.11.6. Since my programmer is a V2.0 do I need to be careful what software I choose as well? Another question is can I program the ATmega while in the detector socket through the 10 pin header? If so, do I turn on the detector power and either give an interrupt command or is it automatic when the programmer is connected?

Thanks

Dan

[reptooyep]

Hi,
The power supply is delivered by the programmer.
The interrupt is done by the rst pin of the 10 pins header.
I don't have any experience with mac but i'm sure someone here can help you with that...

[dantech]

AVRDUDE likes slower AVR clocking then default one.
You should add software/config switch -B6 to slown down. It is most common clock setting

[dantech]

http://chomikuj.pl/dantech/Chance+PI

v170 for ATmega8 and V301 for Atmega328 (still beta)