Help to design a PCB for my PI design!

[1843]

Updated PCB and Schematic?Where? I thought I was On the Last of Revision of this!
Maybe I missed something?more Ic sockets,Im lost an confused!
I must be wasting my Time,Oh No!

Your are on the last revision! Keep on!
The board has more IC sockets doesn't belong to PI-111 !

[1843]

To Night

Hi Night,
Please ask your questions here. There are many experts who can help you sooner than I do.

Can you post a diagram of your LCD connection? What pins...?

The fuse setting(in Ponyprog) is illustrated here!

[Unregistered]

hi 1843 help me pls my lcd problem only bottom line character To exist

[1843]

hi 1843 help me pls my lcd problem only bottom line character To exist

Hi,
Do you get a 2KHz pulses at PB2 ?

[night]

hi 1843 not pulses 2 KHz BP2 atmel become out of order? I fastened without the coil Q2 ,Q9 ,IRF9640 and 7805 is Burned change New. device write and read okey flash is write and read okey eeprom write and read failed..
only bottom line character to exist ..

tanks
regards

night....

[1843]

hi 1843 not pulses 2 KHz BP2 atmel become out of order? I fastened without the coil Q2 ,Q9 ,IRF9640 and 7805 is Burned change New. device write and read okey flash is write and read okey eeprom write and read failed..
only bottom line character to exist ..

tanks
regards

night....

Measure the frequency of PB2 (pin 16) and make sure it is 2KHz. If it was ok, then you have problem with your LCD wiring.
You must use the pins 1-6 and 11-14 of your LCD. In other words the pins 7-10 are not used.

If the frequency wasn't 2KHz, you have problem with fuse bits setting or a wrong or bad crystal.

[Sean_Goddard]

If you have FINAL schematic, I will layout the PCB in four layer with ground screening and impedence matched tracks throughout for you.

I'm currently doing this for the Whites Surfmaster schematic posted on this forum. I've simulated the PCB and the noise is almost non existant as I'ce used differential inputs on all critical stages and full guard rings around inputs AND outputs, so NO leakage AT ALL.

I will layout PCB on ONE CONDITION though, that if you use my design, you build me one of the PI's please as to lay out one of these PCB's will take around a week to get perfect.

I am VERY busy with five projects at te moment, but I will fi it in when I find the time. just tell me which schematic you are using

Check out the Surfmaster so far.

[Sean_Goddard]

Not finished yet, Very low noise though

Two layer ultra fine clearances (must be professionally made) impedance matched traces, star ground (not yet added) analogue one side, digital on the other, and I MAY make it four layer with a ground plane and screening cans with feed-through filters on the supply rail to each stage. This will be the ULTIMATE Surfmaster PCB when it is done.

[Rov]

Surfmaster??? PI-111??Whats this?

[Sean_Goddard]

The PCB I posted is a Whites Surfmaster (unfinished) clone. Just to show you what a PROFESSIONALLY designed PCB looks like and shows you what CAN be done to make this Atmel based design very quiet too (note the GROUND traces around ALL inputs AND outputs)!!

I have not divided up the analogue stage to add screening cans on this version, but MAY do that on a Mk.2.

The original Whites board could be so much quieter if it was designed in the way I am doing it. I have spent three months calculating placings and copper dimensions for the best possible board. When it is finished, I will post the PDF and the Protel format of the PCB here.

Laying out a board in this manner means that the analogue path MUST be done by hand with accurate measurements taken as you go along to ensure correct matching of stages.

This unit has the non-motion pinpoint mod added.

[moodz]

noise and careful design.

What an interesting read this thread is ....
I have just registered with geotech.

Here are some photos of my version attached ...

Note the careful layout

Oh and I made some changes ... to remove alot of noise issues the coil feed line passes through a bifilar "balun" ... it does not affect the pulse.
ie reduces the unbalanced antenna effect of the feedline. ( I used to be an RF guy )

I use a CA3130 as first amplifier ( FET inputs ... much higher input Z )

The uP is a DSPIC 30F4012.

A switch mode supply provides 16 volts for the analogue no sync.

A 12 volt batt pack from a $15 dollar drill powers the circuit for 4+ hours.

[Sean_Goddard]

Darn it.. Why didn't I think of that? That balun is a top idea. I'll incorporate that into my Surfmaster design if you don't mind

[simonbaker]

What an interesting read this thread is ....
I have just registered with geotech.

Here are some photos of my version attached ...

Note the careful layout

Oh and I made some changes ... to remove alot of noise issues the coil feed line passes through a bifilar "balun" ... it does not affect the pulse.
ie reduces the unbalanced antenna effect of the feedline. ( I used to be an RF guy )

I use a CA3130 as first amplifier ( FET inputs ... much higher input Z )

The uP is a DSPIC 30F4012.

A switch mode supply provides 16 volts for the analogue no sync.

A 12 volt batt pack from a $15 dollar drill powers the circuit for 4+ hours.

I love that construction layout! No PCB! It reminds me of the old time radio wiring where everything is attached to the chassis. Really nice! Very creative design. How well does it work?

I'm interested in the balun concept. Would that apply to VLF metal detectors also?

Cheers,

-SB

[Aziz]

Hi moodz,

Note the careful layout

Oh and I made some changes ... to remove alot of noise issues the coil feed line passes through a bifilar "balun" ... it does not affect the pulse.
ie reduces the unbalanced antenna effect of the feedline. ( I used to be an RF guy )

nice layout!
It seems, you have a 1:1 current balun. Isn't it? (it is difficult to see the details). What about using a 1:4 or 1:9 voltage balun? (almost inherent noiseless amplification).

Aziz

[moodz]

re balun mod

I was having the same problems with noise getting into the front end amp and though the switching 16 volt supply would be generating way more hash than a switched cap supply 7660 I could see from the circuit that essentially the amp has an antenna hanging off it because the coil is not differential.
ie one side is grounded and the other is fed to a high gain amp .

On that note why hasn't someone come up with a differential coil sensor for PI ? A differential coil sensor would be inherently self shielding from EM interference but still sensitive to magnetic fields.

OK the balun idea was tried on a whim ... I thought at the time that it would not work ... but then why not ... the balun is used in many situations where you need to couple an unbalanced Z ( pi circuit ) to a balanced Z (coil ) and the balun is ideal for broadband applications ...
ie keep broadband common mode interferance out ... but pass differential pulses ( also broadband ) which is what we want in this application.

I have not experimented with a voltage mutiplication scheme ie 1:4 or 1:16 balun however it may raise the possibility of driving coils with extremely low impedance ( ie inductance ) as the balun would appear to 'magnify' the inductance. Providing the benefit of an extremely 'fast' coil.

If anyone wants to use this idea you are welcome ....

To make a simple balun .... I find the best supply of the ferrite core comes from an old PC power supply where they are used as chokes . Locate a yellow / white toroid 1 " diameter ( doesn't really matter however make sure the toroid is not too small or the current pulse will saturate it ). Remove the original single winding. Wind on approx 10 turns of twin lead ( bifilar ) evenly spaced around the toroid. Secure with tape or glue and your done. connect the coil to one pair and you PI to the other. The balun should be as close as possible to the electronics to gain the full effect.