Surf PI - successful build

[chrisw]

Hi Ken,
I tried Georges idea of reversing the diode and connecting the cathode to the -5v. Right by the side of the diode connections in the pcb was a small hole which beleive it or not was connected to the -5v. So all I had to do was move the LED flying lead 3mm to the right and reverse the diode. So the mod only took 2 minutes. Unfortunately it still doesnt work; the LED is permanently on now and by varying the preset the LED just gets a bit brighter. So maybe I still need the track alteration.

[Qiaozhi]

Hi Ken,
I tried Georges idea of reversing the diode and connecting the cathode to the -5v. Right by the side of the diode connections in the pcb was a small hole which beleive it or not was connected to the -5v. So all I had to do was move the LED flying lead 3mm to the right and reverse the diode. So the mod only took 2 minutes. Unfortunately it still doesnt work; the LED is permanently on now and by varying the preset the LED just gets a bit brighter. So maybe I still need the track alteration.

The confusion here was caused by the LM311 having its inverting input on pin 3, and the non-inverting on pin 2; which is the other way round from other similar devices.
Also (when I suggested connecting the LED to -5V) I forgot that the LM311 has an open-collector output, so that's not going to work.
I'm afraid a cut-and-strap operation is the only alternative.

[chrisw]

Thanks for your investigatory time consuming research George it is appreciated. I will give the track alterations a look next.

Chris

[SVEN1]

I started up on a second board, everything is working to the point I am at.
So I will have to take a look at the LED section.
Thanks George for the upcoming revised Gerber files so everyone has a new reference tool.
Email is the same, if you need it again, will send it off to you.

[chrisw]

I havent fixed my led problem yet but I made a video today showing the depth test on my Crossbow; its an awesome detector board check it out;
http://youtu.be/wH4avCfVdHk

Chris

[Qiaozhi]

Email is the same, if you need it again, will send it off to you.

Sven - please can you send me an email? I sent you a PM yesterday about this. When I used the email address associated with your Geotech account, it bounced back as unknown.

[kenny444]

I havent fixed my led problem yet but I made a video today showing the depth test on my Crossbow; its an awesome detector board check it out;
http://youtu.be/wH4avCfVdHk

Chris

Sorry can you direct me please? I went to the Treasurelinx site, but could not find the "Crossbow" only the "Mirage PI" is it the same thing, thank you very much.

[sinclairuser]

i couldn't either, so i PM ed sven and they are not on yet, chris is a beta tester and sven said his is the first board running( of this board design).
he can explain better send him a pm, i would have grabbed a kit if there had been some, i have learned the lesson on this forum that you should grab kits when they come along.
even if you put them to one side for later on, i kick myself for not getting one of KT's cobras when he had them, always wanted a cobra and kt 315 did an excellent job oh well.
so even though i'm doing the mini pulse, and knocking up an arcade for a mate, i would have got one for a rainy day.

[chrisw]

Hi Guys,
Sven checks out these posts and Im sure will repond shortly. He is the man to speak to.

Chris

[kenny444]

Sven has emailed me, said he will order C version boards, with correction (Thank you George) when he has an interest list of 10 persons. I have said I would take two units, the B series were $13 so something similar I would presume plus the postage etc Paypal accepted. If you want one contact Sven. Regards to all.

[SVEN1]

HI,
The Crossbow is not mentioned on my website at this time, just the Mirage.
The Crossbow was intended as a personal project after seeing the glowing reports of those that bought one of the orig. 12 Crossbows built by George.
Since it was not possible to purchase a built Crossbow, George sent me files etc. to build Rev. B, which was not tested built yet. I took on the project with two others and had 5 PCB's made.
Due to this or that, only one built was completed with good results with difficulty. Remember this is an advanced project like the Hammerhead, if you don't know what your doing............
Anyways, I sidelined the project for 2 years concentrating on the Mirage PI. On my Mirage builders forum for those that bought a PCB from me, a question was posted if I had thought about
ordering some more Crossbow PCB's and giving the project another try. There was enough interest to for a restart and order a min of PCB's. So 6 of us are attempting the build again.
A number of Geotech forum members are on board helping out with this project.
Chris has the first one working with superb results, the rest of us are somewhere along in the build.

Due to the latest posts on Geotech, some other members might be drawn to this project, which is great. For a first project, your better off with building George's Min-Pulse Plus before even
attempting the Crossbow. Right now consider the Crossbow project in Beta-mode.

George just send me Crossbow Rev C Gerber files which corrects Rev. B LED error on the PCB.
For anyone interested in a Rev C PCB, I will have a batch made to order once I reach a min amount of 10.
Due to currency value changes, pricing will be in US dollars.
$13.00 per PCB , plus shipping to the US $8.50, Europe $11.00
PCB's are of high quality.
Please PM me if interested.
I do have sub-forum set up with all Crossbow info for those who get a PCB from me to help those building the Crossbow.

[chrisw]

Hi George,
When I made the LED modification by altering the tracks it still didnt work.
The only way I can get it to work is to remove C26. I dont know if its the wrong size or just shouldnt be there or maybe its doing
its job and only letting the voltage drop very gradually. If this is the case I cant set it up correctly because the LED stays
on all the time once it triggers. I am not into electronics enough to understand this.
Will it hurt to leave it out or shall I change the value?

Chris

[SVEN1]

Chris I changed the tracks on my board as well yesterday. I have not put in the IC yet to test it out.Personally don't care if this feature is installed or not.............if it can be left out, fine with me.

[chrisw]

Hi Sven,
I was going to leave it out, the board works fine without the chip installed, but I have designed the decals for my box and I didnt want to have to change it. It works fine now without the capacitor. It will be interesting to see if your does the same as mine.

[Qiaozhi]

Hi Sven,
I was going to leave it out, the board works fine without the chip installed, but I have designed the decals for my box and I didnt want to have to change it. It works fine now without the capacitor. It will be interesting to see if your does the same as mine.

I went back and looked at the REV-A schematic, and there's a note above the battery warning circuit which says: "LM311 has pins 2 and 3 swapped over when compared with other comparators. The LM311 symbol legend is incorrect in this schematic. Adjust R50 to light LED when battery voltage is 10.5V."
I have corrected this in the REV-B layout.

However, under the circuit, there is another note: "Pin 1 should be connected to pin 4."
So, I suspect that's the root of the problem, as pin 1 is currently connected to 0V.

Please give that a try. If you can confirm the circuit works, I will update the REV-B Gerber files I previously sent to Sven. Hopefully, no boards have been ordered just yet.