The Eggfinder Mini - A Very Small GPS Tracker

Crazyrocket said:

Can you post a picture of where you put the Aeropoxy on the GPS antenna. I am not picturing it too well at this point. Thanks!

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Sure, It's in #57 in this thread: https://www.rocketryforum.com/showt...-Very-Small-GPS-Tracker&p=1680403#post1680403

I see the mini has the pads on the sides of the board so I think a fore and aft fillet is going to be workable here. I'm going to try to build one tonight.

Kurt

KenRico said:

Dont forget a drop of epoxy on the batt connector where it meets the board !

Kenny

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I've learned over the years if a part has the potential to wear out and need replacing, using a permanent installation can make
it difficult to make a repair. Maybe hot glue on top of a direct wired connection or something that would not be too hard to
remove if having to desolder a terminal block or wire. The GPS module is less likely to break with epoxy fillets and if the hit
is a direct ballistic rocket-to-earth hit, the board is going to be trashed anyways when it breaks out of the mounting screws.
Don't ask me how I know!

Kurt

Received two minis yesterday and built them in a few hours as there are not many parts. Mounting the gps has been made much easier with the large through holes to assist in soldering the ground plane to the board. The addition of some via holes on the boards edge makes it easier to solder the connections. A very small tip on your iron and magnification are really needed. Mounting the diode is the hardest part. I filled my power hole on the first one I made. The second time I attached the power connector before soldering the diode- now the diode is easy to solder! Another diagnostic to add to the library.... power up, one blink, then nothing. Did not get a good bridge on one of the RF modules data lines. Both working! Hopefully we will see a programing utility to set the frequency as getting access to my receivers guts is not so easy. Really great kit and fits those tiny rockets too! Small enough to attach to cords! I have attached a picture of the front and back as none exist yet on Eggtimer site to assist you with build orientation.

How'd you do the 3 pin header? Looks different than the instructions. Is it a better variation than shown in the assembly pics? Kurt

re 3 pin connector: trimmed a bit of length, bent, mounted. photo angle doesn't show it too well

Thanks��

That 3 pin connector leaves a tough clearance for getting to the programming pads. I will do as you have done and clip them down a bit on the next one. I'll also probably do a wire bridge on the "Run" pads as that should be easier to disconnect than the solder bridge. I think a short piece of solid core wire will work well for this. The program pads I will just tin and leave disconnected, so I don't have to find the solder if I ever want to reprogram.

I also like putting the JST on before the diode. That will save some pain.

I hope no one reading, including Cris, takes any of these comments as a criticism of the device. The thing is amazingly tiny for what it does, things are inherently going to be tight.

Hey, I like feedback...

I kind of agonized over the header and the pads, I ended up putting in the header rather than something else (maybe a JST-XH, one of those little connectors) because it didn't require a pigtail to connect to the pairing cable. That would have run the cost up, for something that you're going to use a few times, maybe. Most people that I've spoken with change the frequency on their Eggfinders exactly ONCE... to "their" frequency/ID, then they leave it there. Considering that, the header/solder-pads was a reasonable choice. You'll notice that in the picture of the GPS glue joint there's no header... I removed it after I programmed it to make it easier to fit into a Dino Chutes 1" shock cord protector. Yes, it fits... along with a 300 mAH 2S LiPo.

I'll probably suggest that users put a toothpick into the "+" battery pad before they solder the diode, like I do with the TX's antenna hole before you solder the RF module's antenna pad. That should take care of any issues.

cerving said:

Hey, I like feedback...

I kind of agonized over the header and the pads, I ended up putting in the header rather than something else (maybe a JST-XH, one of those little connectors) because it didn't require a pigtail to connect to the pairing cable. That would have run the cost up, for something that you're going to use a few times, maybe. Most people that I've spoken with change the frequency on their Eggfinders exactly ONCE... to "their" frequency/ID, then they leave it there. Considering that, the header/solder-pads was a reasonable choice. You'll notice that in the picture of the GPS glue joint there's no header... I removed it after I programmed it to make it easier to fit into a Dino Chutes 1" shock cord protector. Yes, it fits... along with a 300 mAH 2S LiPo.

I'll probably suggest that users put a toothpick into the "+" battery pad before they solder the diode, like I do with the TX's antenna hole before you solder the RF module's antenna pad. That should take care of any issues.

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Ummmm, I suspect with the popularity of the units Cris there is the potential for frequency and ID clashes coming up soon at larger launches. I would be so progressive as to suggest that major launches have a flier accessed spreadsheet that
they can fill out their frequency particulars in advance as an informational service. In that manner, other fliers can reprogram theirs in advance so not to clash. EggFinders and TRS's can have their own header, Missileworks their own, the Ham Guys
can just "fill in frequencies for their trackers and there can be a list for "all others" say like out of production units or limited production GPS trackers.
There could likewise be a list for RDF stuff.

I've seen things like this listed on boards in the past and it would help avoid having to tear a rocket apart just to reprogram a tracker. If one has a fixed frequency tracker, they can make that known so others with frequency agile units can reprogram
accordingly in advance out of courtesy. Kurt

Some clubs do a member frequency registry so they know who's using what. Some have a frequency posting board at the RSO/LCO table. And some (most?) don't do anything at all, leaving it up to the flyer. My advice at this point is to always turn on your receiver first, let it run for awhile to make sure that nobody's on your frequency, then turn on your transmitter right before you go to the RSO/LCO. The only conflicts that I have personally seen have been on the default 915/0 frequency/ID... that's why I recommend changing it.

Some clubs do a member frequency registry so they know who's using what. Some have a frequency posting board at the RSO/LCO table.

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That's what we do in Tripoli down here in Victoria. Works well. We had a frequency clash at one launch that showed instigating the procedure was necessary.

I mainly was suggesting for large launches. Where I go we're lucky if 10 people show up to fly and then one or two have trackers. It's usually one or two Hams and I've been the only one who does EggFinders/TRS so far. I do APRS tracking too.
If a club has popularly attended launches, frequency control could be desirous. If a launch is announced on an internet site, folks could pencil in what they're frequencies (and/or id's) are in advance and then can plan accordingly.
Sure their might be some no shows but worth trying if clashes start to happen. Kurt

There were a lot of people with Eggfinders at LDRS last year, and I'm not aware of anyone that had issues. I had some conversations with the ROC staff, and they hadn't hear of any either. But it IS just a matter of time before this becomes an issue, so being proactive is certainly a good course of action.

warnerr said:

Received two minis yesterday and built them in a few hours as there are not many parts. Mounting the gps has been made much easier with the large through holes to assist in soldering the ground plane to the board. The addition of some via holes on the boards edge makes it easier to solder the connections. A very small tip on your iron and magnification are really needed. Mounting the diodeView attachment 315940 is the hardest part. I filled my power hole on the first one I made. The second time I attached the power connector before soldering the diode- now the diode is easy to solder! Another diagnostic to add to the library.... power up, one blink, then nothing. Did not get a good bridge on one of the RF modules data lines. Both working! Hopefully we will see a programing utility to set the frequency as getting access to my receivers guts is not so easy. Really great kit and fits those tiny rockets too! Small enough to attach to cords! I have attached a picture of the front and back as none exist yet on Eggtimer site to assist you with build orientation.

Click to expand...

Looks good , another fine build Warner .. looks like your ready to fly in Stereo

Kenny

At a recent launch we had several conflicts. I have three trackers, soon to be four, all on different freq. Even though I only run one at a time. We are now talking about setting up a frequency board. They are getting more and more popular. Which is a good thing!

Looks like I dorked up my first Egg-thing. I guess I didn't heat the alignment pin enough before removing. :sigh:



I offer this as a warning, and an example of what not to do.

Edit: looking at the board that trace appears to go directly to one of the GPS through mount holes, which appears to also tie into the second pad from that side of the hope Rf connection. Could I just bridge a wire from this pad after the Rf module is in place directly to the GPS. All appears to be one big happy connection anyway. This has to be more complicated than that isn't it?

Edit2: Contacted Cris, and he says it is a ground, and since there are 7 more I will probably be ok...woohoo.

Edir3: It works. Looks like I messed up possibly the one place I could have...better to be lucky than good.

The edge via half holes so nothing electronically- they are there to help you get the heat to the edge pads on gps[emoji106]

ksaves2 said:

Where the Rf module sits has no bearing on the GPS receiver. One just wants the GPS antenna "pointing out". The Rf modules energy is routed out the
antenna so where it sits on the board is irrelevant.

The screw hole thing could be of concern for someone who would plan to mount this in a larger tube. If in a minimum diameter project, would just need fore and aft
thrust blocks as the tube would keep the unit in place. Choose the EF according to what it is going to be used for. Kurt

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Anything that the GPS signal has to travel through is going to reduce the signal strength, be it be a nose cone, sled, battery, altimeter or RF module. Also being the RF module it is also going to add a bit of noise to the GPS receiver being so close. Just something that should be kept in mind.

SpaceManMat said:

Anything that the GPS signal has to travel through is going to reduce the signal strength, be it be a nose cone, sled, battery, altimeter or RF module. Also being the RF module it is also going to add a bit of noise to the GPS receiver being so close. Just something that should be kept in mind.

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Ok, I'll concede you are correct if the base of the GPS is facing the the sky and the antenna is face down on the ground. Looking through the RF module I expect has the potential to attenuate the lock. I did a drive with the antenna facing up on the dashboard and had a 10 out of 12 lock most of the time. Interestingly I only had 5 or 6 last nite with a quick test out in the garage but I didn't leave it on for long.

Only beef I have is not with the Mini but GPS Rocket Locator is consigned to using OSM maps and the datum line from the base location to the rocket is white and hard to see. Also the altitude digits don't show well either in the upper left.
Things were fine with a color map but the if OSM is going to be the only options, might help if the course line to the rocket showed up better. Only thing I could suggest is to zoom out and see if one can pickup the rocket position and go from
there.

I have to read up again on programming the stock EggFinder and I suspect I'll have to remove a solder bridge on RUN and add one on PRGRM. When done, will have to reverse. An "L" shaped piece of bare wire should do it. Tack solder and desolder when done. The tail of the "L" will give one something to grap hold of to put on and off. A little tedious but understandable due to the small size of the Mini.

I'd suggest if anyone flies at larger launches to pick out a frequency and ID that's not stock to avoid issues with others. Kurt

Hey Cris,

Thanks for another thoughtfully designed product. I spent a couple of hours this evening working through my first build with no issues. I appreciate the heads-up about the diode & the battery lead. It helped things go smoothly.

My little carbon fiber, 29mm MD rocket has seen many Estes F15s. Time for an H238 and a Mini.

Igotnothing said:

My little carbon fiber, 29mm MD rocket has seen many Estes F15s. Time for an H238 and a Mini.

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Stick an I205 in that puppy...

cerving said:

Stick an I205 in that puppy...

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h399, i224, i243 :-D

I got my mini on Monday and got everything together and it passed all of the initial testing. Soldering the GPS unit on is a pain in the butt. I did not follow the direction for mounting as the soldered leads were seated too far in and I could not get the module to sit flat on the board. I ended up removing the leads and carefully taping the module in place and soldered it up. I just need to reprogram it and mount the LCD system into the box. I will be flying in this weekend at LDRS and will be taping it to my harness. Hope it holds together!

I love the product and you cannot beat the price!

Put mine in a Recon Transmiter Protector from Wildman this weekend !

https://www.wildmanrocketry.com/ProductDetail.aspx?product=7173

Just attached to shock cord of my V2 and the Patriot ... this time I did tape it and the battery to a scrap piece of G10 instead of each other ..

Worked Great !

Kenny

dhbarr said:

h399, i224, i243 :-D

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Zounds! Tickling the waiver.

<sets off to go do stability analysis>

Ken, did you clip it to the shock cord or did you physically tape it to the shock cord to prevent it from "flopping" around. The picture in your wildman link shows a quicklink at the top to attach to the shock cord. Thanks!

Just got my kit today. Man this thing is tiny! any range reports? I've had no issues at 15k feet with the regular eggfinder.

Crazyrocket said:

Ken, did you clip it to the shock cord or did you physically tape it to the shock cord to prevent it from "flopping" around. The picture in your wildman link shows a quicklink at the top to attach to the shock cord. Thanks!

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I just clipped it , had seen one fall out of the sky from a few hundred feet without incident so wasnt overly concerned. .. but a wrap of tape can only help.

Kenny

assembled and tested, works great. I still need to epoxy the GPS antenna and I'm trying to think of better smaller way to do the program pins. for now I'll just use 915 since two of my other eggfinders are on that freq.