PI CHIP

[6666]

Hi Max
I built the complete stock Surf PI, and it works very well, with the R22 & R18 problem fixed
but as yet not much spare time to combine the the two projects, ( Pi chip & Surf pi)

[satdaveuk]

Hi Moodz
Ive almost finished this project based round the minipulse 3 with extra refinements, its based around the ATMEGA8-16AU chip.
If you notice on the circuit x9 at the moment is not used but by replacing the gain pot for a twin gang maybe bring it to 10bit sampling what do you think?.
Just wondering with mods wether it would be possible to maybe introduce your design based around the DISPIC30F4012 and or also your front end design, or infact any pointers to improve the design.
Anyway food for thought I know your a busy man, the full spec sheet is on the designers web page as bottom right hand corner of sch1.

thanks in advance

Regards

[moodz]

Hi Moodz
Ive almost finished this project based round the minipulse 3 with extra refinements, its based around the ATMEGA8-16AU chip.
If you notice on the circuit x9 at the moment is not used but by replacing the gain pot for a twin gang maybe bring it to 10bit sampling what do you think?.
Just wondering with mods wether it would be possible to maybe introduce your design based around the DISPIC30F4012 and or also your front end design, or infact any pointers to improve the design.
Anyway food for thought I know your a busy man, the full spec sheet is on the designers web page as bottom right hand corner of sch1.

thanks in advance

Regards

Hi Dave ... The circuit has alot of similarities to the surf PI however I am unfamiliar with the performance .... it may be good or bad ... maybe others on this board have some experience they could contribute ?? ....
Anyway I would advise you complete the project as per the design then maybe we could establish some benchmark measurements upon which to determine if any change we make might actually result in an improvement.
I am presuming the designer knew what he was about ... however straight up we can see that the sync feed for the synchronous power through C6 is right dodgy driving off the receive signal .... As for sampling at 10 bits I am not entirely sure what you mean by using a dual gang pot .. maybe you had some particular scheme in mind .

Cheers for now ... moodz

[satdaveuk]

Hi Dave ... The circuit has alot of similarities to the surf PI however I am unfamiliar with the performance .... it may be good or bad ... maybe others on this board have some experience they could contribute ?? ....
Anyway I would advise you complete the project as per the design then maybe we could establish some benchmark measurements upon which to determine if any change we make might actually result in an improvement.
I am presuming the designer knew what he was about ... however straight up we can see that the sync feed for the synchronous power through C6 is right dodgy driving off the receive signal .... As for sampling at 10 bits I am not entirely sure what you mean by using a dual gang pot .. maybe you had some particular scheme in mind .

Cheers for now ... moodz

Thanks Moodz
Will do ive just got to do the wireing now everythings mounted, the upgrade to 10 bit was actually on the designers web page just repeated what he purposed.
Im back to it after cooking sunday lunch for the family, thanks again.

Regards

[moodz]

Thanks Moodz
Will do ive just got to do the wireing now everythings mounted, the upgrade to 10 bit was actually on the designers web page just repeated what he purposed.
Im back to it after cooking sunday lunch for the family, thanks again.

Regards

OK Dave ... let us know how you go with it ... I see now what you were talking about ...I did not read that bit about the 10 bits I must of only read 9 of them ... ( a little joke there LOL ).

moodz.

[moodz]

Thanks Max ,

I will draw up a schematic on the weekend to indicate where the UNIPI chip can be connected in the surfPI.
The descrimination is a work in progress .... works fine on largish iron obejects but smaller targets like coins etc the results are not so clear ... in other words still working on that LOL. Have had alot of success with a novel coil damping method though that should add a bit more to the puzzle. ( I mean solve a bit of the puzzle LOL ).


moodz

Max ...as promised ... here is your schematic ... I have chopped out everything that was not needed ...could do a bit more chopping however I have preserved the critical parts that characterise the surfPI design ...
The schem is a modded rip from here ... http://www.geotech1.com/forums/showp...7&postcount=18 ... thanks to Jim.

moodz

[6666]

Great work Moodz
is there still a xtal on pins 9/10 ?

[moodz]

Great work Moodz
is there still a xtal on pins 9/10 ?

Ah ... I'll put that in on the next update ...:

Moodz

[hdphilip]

A surf PI home run......

moodz,
now that's cool

the Surf PI with the perfect computer interface, sweet!!!

This takes all of the guess work on setting up the timing!!!

The Mosfet damping would be icing on the cake!!




Philip

[satdaveuk]

OK Dave ... let us know how you go with it ... I see now what you were talking about ...I did not read that bit about the 10 bits I must of only read 9 of them ... ( a little joke there LOL ).

moodz.

Lol, Ok ive wired all up, all thats needed for me to do now is drop the 5v down to 3.2v on my 16x2 which shall do by inserting 3 off in4007s in series , then build a programer for the ATmega, then a coil.
What I will do Moodz is let you know how it fires up on here and then put the project on a new thread because otherwise it will hijack your thread which is unfair and very anoying for others.
Your circuit mods to Jims already nice circuit with his layout all controls fitted on the pcb and gagging for plugs and sockets rather than just soldered on random is a piece of art shall certainly go for that after ive finshed the pulse3 as ive got all main components in stock just sat there.
Thanks for your time
Regards

[moodz]

moodz,
now that's cool

the Surf PI with the perfect computer interface, sweet!!!

This takes all of the guess work on setting up the timing!!!

The Mosfet damping would be icing on the cake!!

Philip

Ok ... I have added the icing .... Q1 is the damping control Mosfet and is controlled by a filtered PWM signal.

Moved the sound to a PWM pin ... so you can have nice tones or clicking ( have to add menu item ).

Added an SPI port to the ICSP port which is also a TTL level RS232 port (so its a three way port LOL ). Never know when we might add some handy SPI chip to the Surf Pro

Added the crystal oscillator ( which was an oversight )

moodz

[moodz]

... and a board to match .... placed and routed but needs more work ..... watch this space.

moodz

[javahitman]

... and a board to match .... placed and routed but needs more work ..... watch this space.

moodz

Hi Moodz,

which software can i use to print different layers of that PCB image ?


Regards,
Denis

[6666]

Hi Moodz
you have been busy, good work
I am but a mere mortal but R36 seems a bit high, is it really a 100k ?
cheers

[moodz]

Hi Moodz
you have been busy, good work
I am but a mere mortal but R36 seems a bit high, is it really a 100k ?
cheers

R36 forms a low pass filter to control the gate voltage on the damping mosfet. We are using the mosfet as a variable resistor here not a pulse driver. Any noise on this will modulate the damping and cause false target noises.

moodz