Surf Pi Pro Build

[Darin]

Hey I am building that same board. You should have waited a few days and we could have worked together..

I drew this schematic it looks similar to other Surf schematics. I haven't verified all parts yet...

[ATTACH]34970[/ATTACH]

Did you get yours from ebay ? The reason I ask is I did and got it assembled and have multiple problems with it. The reason I got the MPP kit from Silverdog, built it without a scope and it seems to be working quite well for the coil I have to work with.
Looking forward to see how your build goes, please keep us posted as I would like to try and get my surf pro working.

Thanks
Darin

I have the schematic that came with mine if it will help any.

[cddz]

Hey I am building that same board. You should have waited a few days and we could have worked together..

I drew this schematic it looks similar to other Surf schematics. I haven't verified all parts yet...

[ATTACH]34970[/ATTACH]

I spent enough time trying to figure the boards quirks out. Too many trips to parts store to swap parts trying to find what part was causing the issue. The next step was to remove the IC sockets and directly solder them to the board. That didn't go over too well, solder plunger pulled a tab off....

[kt315]

no detailed data on original whites board. i am looking for somebody who can help but without success.

[FatBob]

Hey I am building that same board. You should have waited a few days and we could have worked together..

I drew this schematic it looks similar to other Surf schematics. I haven't verified all parts yet...

[cddz]

boom... unusual way to fix off the problem... i can give right schematic, with all mods... if you want....

[ATTACH]34966[/ATTACH]

I don't think this will buff out lol

[kt315]

boom... unusual way to fix off the problem... i can give right schematic, with all mods... if you want....

[cddz]

Well, it is now fixed! The schematic did not even match the board..... guess I will only buy from reputable board makers.

[baum7154]

Sorry I can't be much help as I have never built the Surf PI. I'm sure there is more help out there on this though.

Dan

[cddz]

Anymore Ideas with this? Should I just start replacing parts. The schematic that was included with this is not even accurate to this board...... So many versions of this board and so many different schematics, no wonder there are so many issues with the Surf PI

[cddz]

Testing indoors can be frustrating for metal detector use. There are plenty of sources for interference in any home even if no appliance is turned "on", as there are standby modes etc and switching power, also interference is carried from other apartments by powerlines. Therefore, test outdoors if there seem to be problems depending on where you stand or how you orient the coil.

Capacitance is something that affects detectors as well. Squeezing your coil cable will increase its capacitance, which slows down a coil and requires smaller damping resistor. This is why many commercial PI detectors are slightly over-damped (also for coil change tolerance etc.) Coaxial cable is mostly needed to guard the single-end coil's "hot end" from capacitance, not as much for RF reasons where twisted pair would be enough. You will need to shield the coil if you want to run short delays, since wet grass, ground distance and other things make for a rapidly changing capacitance from your coil to the ground. The shield you did with the mesh was not overlapping itself or making a complete circle?

Your detector will also pick up the cable leading to its coil (and the coil itself to some extent!) which is why some designs use litz wire, curious cables and such for their approach. This is why pushing the cable around near the coil will also make for the magnetic field based false detections, not just capacitance false detections. Coaxial cable is usually quite solid and does not change the capacitance much when bent compared to loose paired wire.

Working on your first detector can be frustrating, I wish you some luck and a lot of patience and determination with it.

No on coax, the coil feed is a continuation of the coil wire, which is Hook-up Wire 22AWG 7/30 PVC. I can touch the coil(as long as the cable doesn't move) and it won't sound off. Maybe I should reattach the +coil wire, that is one joint I did not check......Growing up I would build the kit electronics, many while in High School, never had these kind of issues lol

[cddz]

I have a question about your coil feed, did you twist at a rate of 3 turns per inch and then heat shrink it? Is your coil and feed wire PTFE aka Teflon insulated?

The damping looks pretty good to me.

Dan

It is braided close to 3 turns per inch, the wire is Hook-up Wire 22AWG 7/30 PVC tin plated. After this issue occurred I removed the coil connector, removed the board from the enclosure and used carbon paint to shield it. I left a gap of 1/2 inch x 4 on the top side. I should have mentioned that while testing, I used a known good 10K 10 turn pot to test each pot. When I touch the pot post it would also sound off.

[baum7154]

ODM is correct about testing indoors and false triggers. I cannot carry my detector turned on from the basement to the main floor and outside without triggering on the re-bar in the concrete, the air ducts, floor nails, wiring, and a bunch of other items in the house. Once outdoors the detector also triggers on the red bricks in the patio floor. Out in the mountains is far better than out in the yard too.

This still may not be the problem you are seeing but should be considered and minimized in testing.

Regards,

Dan

[ODM]

Testing indoors can be frustrating for metal detector use. There are plenty of sources for interference in any home even if no appliance is turned "on", as there are standby modes etc and switching power, also interference is carried from other apartments by powerlines. Therefore, test outdoors if there seem to be problems depending on where you stand or how you orient the coil.

Capacitance is something that affects detectors as well. Squeezing your coil cable will increase its capacitance, which slows down a coil and requires smaller damping resistor. This is why many commercial PI detectors are slightly over-damped (also for coil change tolerance etc.) Coaxial cable is mostly needed to guard the single-end coil's "hot end" from capacitance, not as much for RF reasons where twisted pair would be enough. You will need to shield the coil if you want to run short delays, since wet grass, ground distance and other things make for a rapidly changing capacitance from your coil to the ground. The shield you did with the mesh was not overlapping itself or making a complete circle?

Your detector will also pick up the cable leading to its coil (and the coil itself to some extent!) which is why some designs use litz wire, curious cables and such for their approach. This is why pushing the cable around near the coil will also make for the magnetic field based false detections, not just capacitance false detections. Coaxial cable is usually quite solid and does not change the capacitance much when bent compared to loose paired wire.

Working on your first detector can be frustrating, I wish you some luck and a lot of patience and determination with it.

[baum7154]

I have a question about your coil feed, did you twist at a rate of 3 turns per inch and then heat shrink it? Is your coil and feed wire PTFE aka Teflon insulated?

The damping looks pretty good to me.

Dan

[cddz]

Seems Every time I move the detector to a different room something else goes wrong.
If I touch the cable it sounds off. It does this through the entire range of pulse delay and on the other good coil that I made for it. I have tried searching for this problem but can't seem to find the topic. It only seems to happen if I touch the +coil wire. I have changed nothing since 2 days ago, just took a break from it. I have gone back over solder joints(again), can't seem to figure it out. I tried fine tuning the dampening resistor(545R), it didn't help either. Here is a picture of the dampening, maybe some one else can see something this noob can't. Any help is appreciated.