Surf Pi Professional Pcb's back in stock - NEW Prices

[satdaveuk]

Thanks for explaining that Silverdog.

Despite the voltage readings on the 7660 the detector seems to be working just fine with a 9v power supply I just picked up a new Coiltek 14" mono solid coil and it only needed me to tweek the tune and delay settings slightly for it to work. Didnt need to touch the offset.

I can hit most targets with it even small ones at about 30cm. It picks up my car keys at about 40cm.

Very happy with it.

Well its oviously working correctly, For good learning curve make yourself a home made coil for it.

Regards

[gcause]

Thanks for explaining that Silverdog.

Despite the voltage readings on the 7660 the detector seems to be working just fine with a 9v power supply I just picked up a new Coiltek 14" mono solid coil and it only needed me to tweek the tune and delay settings slightly for it to work. Didnt need to touch the offset.

I can hit most targets with it even small ones at about 30cm. It picks up my car keys at about 40cm.

Very happy with it.

[Lefizz]

Maybe that's my issue as well, I have been using a pp9

[silverdog]

The battery snap connector is a generic adapter, it will fit a PP3 9v
I include them normally as I bought a bulk lot
They are intended for use with batterey holders which normallly have the PP3 connector on them, so if you use 8 x 1.5v or 10 x 1.2v then both will connect to the snap connector

[gcause]

Pin 5 of 7660 should be -5v

you may have blown the 7660

you should use 12v as you supply

12v I assumed it was 9v as there was a 9v adaptor lead in the kit.

I will try the other 7660 chip from the other kit

[silverdog]

Pin 5 of 7660 should be -5v

you may have blown the 7660

you should use 12v as you supply

[gcause]

Hi All,

Ok here are the measurements for my Surf PI:

TP1: 4.54V

TP2: was 0.47V but that was before I set pin 6 on the 5534 down to 0V and now TP2 is 0V also interesting

7660: pin 5 is 4.59V and pin 8 is 4.89V

I am feeding the circuit at the +/- at the end of the board with 8.95V but I can regulate this to whatever voltage you recommend.

Do these value look alright?

Regards,

Grant

[TH Jim]

You need to use pots of the same value as specified in the schematic.

[gcause]

Hi All,

Also on the external pots I have a few questions and please exuse my ignorance as I am still learning electronics. Need advice on how to wire the pots. I am getting a spark / flame out of one of them in certain combinations of settings.

Normally when I do external pots on other projects they call for a bridge between the one of the outer legs and the middle leg of the pot and then its a two wire connection from the pot to the board. These boards have four solderpads for each pot but people seem to be only using three of them.

I notice in the pictures that most people run the three wires straight to the external pots which is what I have done and it seems to be working.

I used the back three solder pads and put the solder blobs on these on the back of the board and then soldered the wire onto the solder blobs. I am using insulated speaker wire so I couldnt fit it into the holes from the top of the board. It is working just fine and actually seems to offer a much stronger connection.

On the board there are 4 solderpads for each of the pots I only used the three solderpads that were aligned I did not use the middle 4th solderpad that is in line with the middle solderpad for the connection. I did notice in one picture for the volume pot an external pot using the back two outer solderpads and the 4th solder pad and not the using the one the outer solderpads were aligned with.

So did I wire these up correctly and does this mean there is already a bridge between the middle two solderpads for the pots on the board and it doesnt matter which one use?

Is there a difference for each pot as to which set of solderpads you should use or did I get it right?

Each pot does seem to be working.

However I have noticed when I was tuning in the coil that depending on how you adjust the pots you can get a situation where a small spark / flame will come out of the volume pot and it will glow at its base and start to smoke when it is turned completely off.

I quickly adjusted the pots again and the circuit still seemed to be fine so it didnt burn anything out thankfully. This happened to me twice while I was tuning the coil by adjusting the offset, delay and tune pots. It only happens in a specific combination of the three pots settings.

I am thinking there may be a need for some extra protection in the circuit around the volume pot for an over current situation. Or I may have wired something incorrectly but it all seems to be working.

Regards,

Grant

[gcause]

Hi All,

Got one of my Surf PI kits working today

I was able to get it to use my custom power supply as well a 12v drill battery with a Jaycar power regulator kit regulating the supply back to 9v.

I also wired it up to microphone glands for the coil and the battery as per commercial metal detectors. So this means I can plug in commercial coils and it is currently working with my large Coiltek UFO mono coil.

I have the piezo coming off a headphone phone jack and that going back to the speaker connections on the board so when I plug the headphones in it uses those and the piezo goes quiet. When I take them out the piezo works instead.

So I guess I am not a total loss at electronics after all.

I was beginning to get worried when I failed at getting the barracuda kits going. In the end I had to send the boards to Mr. 6666 who kindly fixed one for me.

However my Surf PI kit is working just fine.

I used external pots for all the but the offset pot which I also want to take out to an external pot as it is too fiddly trying to adjust it with the one that came in the kit.

I dont have a 100K external pot handy so I was wondering if I could replace it with another value pot as I have a 10K, 25K, 50K, 500K and a 1K available. I am hoping I can use the 50K would it be suitable or would it blow up the board?

I was also wondering if I could use the 500K on the Tune pot instead of its current 10K value as I currently have the 500K and the 25K setup in series from another project as tune and fine tune. This arrangement worked well on the other project. Would the 500k be ok on this circuit or would it blow a component or two?

Once I work those pots out I will be able to box it up. I was thinking of using a pringles tin as it is about the same size as the tube Minelab use on their Excalibur 1000, I want to set this up the same way they did.

Thank you for your assistance with this it is greatly appreciated.

Regards,

Grant

[golfnut]

Hey Tex make sure you swap the resistors on u3a

as in other posts of surf.

plus a guy has mods recently that look good - but he has not spilled yet.

steve

[Seeweed]

Just ordered my Surf PI 1.2 Kit

This my first project, I can't wait to get started. The Surf PI looks like one the easier PI kits to get started with. Hopefully it wont take too long for it get here.

[Comp]

Samples on the rising edge,,.. fair way up, (depending on the delay setting....)

I think there is a Surf PI DVD on You Tube, 3 x 10 minute sections,... and the last 15 mins is by a Whites design engineer, explains it really well, I'll see if I can find it, and link...

Cheers, Fred

Here it is,... starts about 3 mins in,,, All good stuff....

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

[golfnut]

Pulse energy

Looking at the schematic on surf, Does sampling for a target occur on the falling edge of the Tx pulse?

If So, why does it not sample for a return on the rising edg too?

As there is just as much magnetic enery in the rising edge as the falling edge.. (If they are similar times and amlitudes)

This way we would double the return energy of the product.

S

[mikebg]

Scary question isnt it.

If your PI isnt doing depth... take a look at your battery choice.


You need cells that laugh at delivering approx 6AMP pulses.

S

Steve, this is not correct. There is a large capacitance connected in parallel to supply rails. It delivers the large current for TX pulse.