Eggfinder receiver case and GPS

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amiliv

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Did anybody have problems with optional Eggfinder GPS module in the Blackaero case? If I lay out boards on the table next to the window, no problems getting GPS fix, generally under a minute or so with limited view of the sky. But once I put everything in the case, it fails to get fix even after 5-10 minutes outside under unobstructed skies.

When assembling, I made sure no wires or cables run over the GPS chip (power, button, BT module and GPS module; all wires and cables are clear from it).

I suspect it's because, once in a case, its view of the sky is shielded by the main board (in Blackaero case it ends up right under it). But on the other hand, this is extremely popular case, and if that's the real problem, there's no way I'd be the first to hit it and/or ask about it.

Or maybe... did the main board changed recently in a way that would interfere with GPS chip if it ends up somewhere under lower left quarter of the main board within the case (my main board is revision B2, if it matters).
 

n27sb

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This is my solution. In the current configuration the GPS antenna is pointed at the dirt. Mounted on the top also allows you to view the LED. 6D98A2F8-284B-4FB3-B839-28EF941E6B23.jpeg
 

amiliv

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Mounted on the top also allows you to view the LED.
Hm. Sadly, if the case was just 1/8" longer (ideally 3/16" longer, but I think even 1/8" would have worked), it'd comfortably fit next to the LCD display. Just like on your photo, but inside of the case. I'd simply cut two slots in those bumps on the inside with a dremel. That'd support one edge of GPS module. Then drill two holes for the screws through the top of the case to support the other edge of GPS module (and an optional hole to see LED through it).

I'm attempting to figure out if it'd fit positioned like in your photo, but inside the case, between LCD and main board. The chip would overlap with the LCD board for just a tiny fraction of an inch, so it'd still provide way better view of the sky. If it fits in vertical space between boards, I think it should. The only thing is that it'd be supported by only two screws along the long edge of the module. Which would mechanically be less than ideal, but I think I can make it work. Like on this photo:

PXL_20210326_211023881.jpg
 

cerving

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... did the main board changed recently in a way that would interfere with GPS chip if it ends up somewhere under lower left quarter of the main board within the case (my main board is revision B2, if it matters).
We did add about .1" to accommodate the GPS header on the later board but it fits fine inside the BlackAero case; I have three of them. The BlackAero case mounting for the GPS has it point at the ground or be mostly obscured by the LCD panel. It would be better if the case was extended heightwise about 3/4" so it could be mounted below the LCD panel with the GPS antenna pointing "up".
 

amiliv

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Hm. Wait. You mount it with GPS chip pointing down (towards ground)? I mounted it so that GPS chip points up towards the sky (i.e. into the case). So it ends up being sandwiched between it's own board and the main board. Maybe that is the problem :)

OK. I'll try flipping the other way around so the chip is on the bottom pointing into ground and see if that solves it.
 

cerving

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No, you misunderstood. It is SUPPOSED to be pointing at the sky like in your picture. I don't know if the way that you have it mounted in that case will work, but it's better than having it point at the ground.
 

amiliv

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I think we misunderstood each other :)

The way I attached it originally was like in the instructions video, with the back of the module towards the lid. So once lid is on the case, the chip points up. I guess I misunderstood the "point to the dirt/ground" part in above replies.
 

cerving

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If you mount it on the backplate, the antenna is blocked by the PC board and the LCD display. I like your method better... it's only partially blocked by the display. It would still be better if the case had more room...
 

amiliv

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Well... I think I have a weekend project to make a bit bigger case. With few more modifications (threaded inserts, etc), while I'm at it.

Last time around, I made custom egg-shaped (if you use a lot of imagination) case. Which is now baking under the Nevada desert sun out there on a random playa... And can't find where I stored STL files. I think I'll just make a simple box this time around, and go artistic as follow up if I feel like it later.
 

amiliv

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We did add about .1" to accommodate the GPS header on the later board ( ... )
FWIW, a tiny suggestion for the next time main board is revised... If standard hex #4 or M3 standoffs are used between boards, they rub against the buzzer on the main board. Moving it few millimeters further away from the mounting hole would be awesome ;-)
 

amiliv

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Well... First fruits of my weekend project. A rough draft if you will.

The case is still basically Black Aero design. Just a bit taller and using threaded inserts for attachment points instead of through-the-case screws. Added hole for the second switch (backlight) as well as hole for GPS LED. Excuse a bit of "dirtiness"... Previous filament was black polycarbonate (PC), and for some reason it tends to stick in the extruder and "contaminate" next print or two. This prototype case was printed in orange PETG.

PXL_20210331_052724270.jpg


LCD board and GPS module fit inside a larger case side by side. Yay! The hex standoffs screw into threaded insert under the LCD board, keeping it securely attached, as well as provide support and attachment point for the main board. These were metric 11mm long hex standoffs, which is just shy short for distance between boards; hence thin washers. 11.5 mm would be ideal. The washers are a bit wide for my taste, I'll try printing narrower plastic washers; they'll be gentler to the PCB too.

PXL_20210331_054154676.jpg


And here it is with everything inside and connected. There are some plastic #4 washers under the M3 screws. The head on M3 is commonly 6mm diameter, while head on #4 is just shy of 5.5mm. I should probably find some 5mm or 5.5mm head diameter M3 screws.

Except for the Bluetooth module. It'll attach to the lid, like on the original Black Aero case. However I plan to position it horizontally so its connectors are aligned with connectors on the main board; should make for a bit simpler cable routing.

PXL_20210331_064638819.jpg


The side has (S)witch, (L)ight and Power markings.

PXL_20210331_064705791.jpg


Some areas for improvement:
  • The two momentary switches look atrocious... Need to find something better looking. I simply re-used switches that came with Black Aero case and with Eggfinder receiver for this prototype. The feel on these momentary switches is terrible as well. The on/off switch is really good. I'll keep that one.
  • Should have labeled the button switch with B for button... Not S for switch.
  • The light switch should be replaced with rocker switch (like the power switch, but then danger of confusing them, maybe non-momentary push switch?).
  • Move the switches for button and light a bit further apart.
  • Heads on regular M3 screws are a bit too large (6mm diameter). If not for the plastic washers under the screws, two of the screws would almost touch exposed contacts. I think I have some M3 screws with smaller 5mm heads somewhere, someplace. 5.5mm would likely work too, it's about same head diameter as on #4 screws. Looks like McMaster has a narrower 5.5mm head diameter M3 screws under JIS (Japanese standard) category. Not a big deal since plastic washers are a good idea anyhow to protect PCB.
I still need to finish the lid, halfway there... The original handle will fit on this case, so I can reuse that one... But I might print my own so it's a matching color.
 
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amiliv

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Uh. Was scouring Digikey for nicer looking pushbutton switches that would fit... Not much choice there given space constraints. Found these NKK HB series switches that are not exactly beauties and would maybe fit maybe not in the space between boards... At whooping price of about $10 per switch. And these E-Switch LP1 series at much more reasonable price, but there's no non-illuminated version. Their RP8500 series looks nice, but it doesn't seem Digikey has them (and not sure about fit yet). NT Electronics S127 series might be a very tight fit too, but not beauty winner. Search continues...
 

amiliv

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Just as follow up. Made few changes... Switched to M2.5 inserts/standoffs/screws for mounting the boards. Much better fit. Kept M3 screws for the handle/lid/clip attachments. Engraved the "Eggfinder" down the handle.

I ended up using NKK HB switches, non-illuminated option with solid caps, regular momentary for the button (HB15CKW01-C) and latching for the backlight (HB16CKW01-G). They are very high quality, nice click and good feel when they are pressed. Expensive at $8 each at Mouser. I used 12mm spacer between boards to have comfortable clearance between switch and both boards.

The E-Switch LP1 are more economical choice at about $2 per switch, Not as good as HB's, but still a good upgrade compared to the switch that comes with the case. They only come with transparent cap. Much more compact than HB switches and only momentary option (i.e. user would need to hold backlight button pressed, some people may prefer that).

Either switch will mount nicely through 8mm hole (I made it 8.1mm to have some tolerance). Since both these switches are inserted from the outside a way to disconnect/reconnect them from the board during installation is needed. I got a JST PH connectors with lead wires, and connected that to the board and switches instead of wiring them directly. I swapped out wires between connectors so that I have one set with all black wires, and another with all red wires (they are crimped, carefully lift plastic tab on connector and pull out the wire, and insert it into the other connector). So that they are color coded (all red wires for button switch, all black wires for backlight switch).

I kept the on/off switch that came with the case (AFAICT, it seems to be ZF Electronics PR series, part number PRK22J5DBBNN).

So, few days worth of designing, prototyping and searching the Internet for parts later, which simply buying the case off the shelf was supposed to avoid... not to mention many many hours of printing all the prototypes... I have an ultra cool uber upgraded Blackaero case... Which still looks like utilitarian box compared to my original old case design. I'll have to recreate that one one of these days.

Hey, but at least it was fun.

Oh... And in the meantime, I managed to find the Eggfinder receiver that I lost in the middle of Nevada desert. So, now I have two receivers. Turns out, on the playa you can spot tiny things from many hundreds of feet away. I simply walked to the approximate area where it should be, spotted it from far away, and walked right to it.

The old lost then found case vs. new case...

PXL_20210412_004421693.jpg
PXL_20210412_004939539.jpg
 

cerving

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I recommend using tape or heat-shrink to insulate those bare switch terminals. I've seen some issues with cases in which the terminals are very close to the board...
 

amiliv

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I recommend using tape or heat-shrink to insulate those bare switch terminals. I've seen some issues with cases in which the terminals are very close to the board...
Totally agree. Might not be visible on the photo, but there's actually decent clearance between terminals and the board. FWIW, the two bare terminals on the outside are for LED, but these two switches are part numbers without LED, so the two LED terminals are not connected to anything on the inside of the switch, because, well, these part numbers don't have LED in them. Regardless, should have put some heat-shrink on them for extra safety.

The switch that is between the boards is of more concern. Because it sits right above RF module. I went with a bit too long 12mm spacer between boards (the "normal" spacing between boards should be 7/16" or 11.11mm) to get it a bit more additional clearance there. This results in a small (bit less than 1mm) gap between headers on the main board and LCD, but the pins are still inserted enough to have reliable contact, and the entire thing is firmly fixed with mounting hardware.

My bigger concern was the metal mounting ring (nut) on the outside perimeter of the switch. I made the case a tiny bit wider than it needs to be and also recessed the wall around the switch hole on the inside to ensure the metal mounting ring is not extending over the RF module (and thus can not touch it). The two switches end up positioned like this between boards (though, in reality, it visually looks like a bit more distance on an actual real world assembled part):
Modified Blackaero Case v117.png
 

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