The Eggfinder Mini - A Very Small GPS Tracker

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The short version: Don't use a 1S LiPo.

The long version: If you use a freshly-charged 1S battery it will "appear" to work, however the threshold voltage of the regulator IC is 1.0V, so the minimum input voltage to get 3.3V out of it is 4.3V... about 0.1V higher than what you get out of a just-charged LiPo cell. At the LiPo's nominal voltage of 3.7V, you don't have enough voltage to feed the regulator, so it basically acts like a diode dropping the the input voltage about 1.0V, to 2.7V. The minimum input voltage for the RF module is 2.4V, but for the GPS module it's only 3.0V, so you're 0.3V BELOW the recommended input voltage of the GPS. You'll probably get an RF feed (weaker, obviously because you're running at a lower voltage), but chances are that your GPS data will be sketchy at best. Bottom line: Use a 2S.

BTW, there are regulators with lower dropout voltages than 1.0V, however none of them can source enough current for a RF module and a GPS module. It takes 250 mA minimum to guarantee that there's enough current for the GPS' startup plus the RF module's nominal transmit power.
 
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Bump to this thread.
I have some 600mAh 1S lipo batteries that I have been using with a newly assembled Eggfinder mini. It seems to work fine for a basic functional test around the house.
Is there any concerns with using a 1S instead of 2S? Lower range or runtime? I don't know where the voltage cutoff is.

I also tried the same battery on the deployment power of an Eggfiner TRS and it would NOT fire e-matches, so those definitely need the 2S.

Read Cris' note. Guy lost an L3 cert running an EF mini on a 1S battery last year. DON'T FLY A 1S battery here PLEASE!!
Kurt
 
Yup, this is exactly what I was looking for. None of my searches got me to a post detailing that out.
Tis no problem, just wanted to check first.
When I did my test it seemed like I was getting a lower than normal number of sats in view. Will load up a 2S and retest.
 
From a hardware point of view, yes, Bluetooth to an iPhone is certainly possible. Unfortunately, Apple does not support either serial Bluetooth devices nor external GPS devices in iOS, so you can't do it. Android does, which is why a lot of people use cheap Android tablets with Rocket Locator with their Eggfinder. Personally, I'm OK with manually entering the coordinates into MotionX.

Either the Eggfinder RX "dongle" or the Eggfinder LCD display receiver can be used with an HC06 Bluetooth module to provide a wireless feed to an Android running Rocket Locator. With the LCD, you also get the coordinates on the display as a backup... good to have in case you lose the Bluetooth feed.

..................Or hack ham radio software to navigate on a map: https://www.rocketryforum.com/showthread.php?137555-Eggfinder-Map-tracks

GPS Rocket Locator is the simplest though. It was advertised as being able to cache Google maps for offline use but I believe that is no longer the case.
I emailed the author and he said he will look into it. I noticed it when I tried to cache with a $49.00 Teclast X80a Christmas special. Might have been
my device though. On the flip side, the Open Source maps downloaded and cached properly. It's easy to simply walk toward the last known position and
of course when a new final position comes in, you have it made. Kurt

Maybe I'll snag a BTLE module and see if I can get iOS to do anything useful with it. I'm not gonna reinvent the wheel, though... unless it's an easy hack, something like Rocket Locator for iOS isn't in the cards.

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

Has anyone found a workaround to cache the maps for "Rocket Locator" running on Android? Are there any alternatives that will work with the Eggfinder mini over BT to my Android?
 
Has anyone found a workaround to cache the maps for "Rocket Locator" running on Android? Are there any alternatives that will work with the Eggfinder mini over BT to my Android?

Sure, not to sound snippy but the OSM maps I believe are still cacheable. Someone correct me if I'm wrong. The Google Maps are not coming back.
If someone recodes the program to use the ArcGIS photomap set that is a bit dated but is still very usable the would be workable.

Rest assured, there is no "perfect" mapping program out there for rocketry but they all can help to find rockets. When I mean "perfect" I mean caching, storing data, using photomaps versus line maps, having a rocket icon that has the pertinent data next to the moving rocket icon, easily calling up data tables, stuff like that. They'll all work but some have features that would appeal to different people if they have different desires.

The other NMEA tracking program Rocket Track (you'll have to look up the download link somewhere on TRF) get a live non-cacheable photomap that's fine as long as one
has a live data link. I keep both on my devices. Kurt
 
Are there any alternatives that will work with the Eggfinder mini over BT to my Android?

I use Bluetooth GPS app on my android tablet. https://play.google.com/store/apps/details?id=googoo.android.btgps&hl=en_US You get mapping, satellite status, and can see the NEMA data. I don't think this app allows you to download the NEMA data but I've never tried. I just use the map to get a visual reference when needed. Never had a problem running it. You have to disable location on your tablet before pairing with LCD bluetooth. With the new GPS module for the LCD I don't find the need for an app with my position and rocket position (I also never had much luck with Rocket Locator even before the LCD GPS module). Just having the map visual is enough to get me heading in the right direction. Used this app/setup multiple times this past weekend to quickly find rockets hiding in 4-6 foot tall grass.
 
I use Bluetooth GPS app on my android tablet. https://play.google.com/store/apps/details?id=googoo.android.btgps&hl=en_US You get mapping, satellite status, and can see the NEMA data. I don't think this app allows you to download the NEMA data but I've never tried. I just use the map to get a visual reference when needed. Never had a problem running it. You have to disable location on your tablet before pairing with LCD bluetooth. With the new GPS module for the LCD I don't find the need for an app with my position and rocket position (I also never had much luck with Rocket Locator even before the LCD GPS module). Just having the map visual is enough to get me heading in the right direction. Used this app/setup multiple times this past weekend to quickly find rockets hiding in 4-6 foot tall grass.

It's fine but one needs a live internet connection to get the map and one has to set their Droid to "allow mock locations" after one gets the device into the "developer options" mode
to use the Bluetooth GPS app. It can give you a rocket position but it won't give you your position with a datum line to the rocket hence not useful for direct navigation but
it's enough for some people.

GPS Rocket Locator can be squirrelly but it helps to be out in the open and make sure your HC06 or HC05 board has a good connection (I've had better luck with the 05 boards but
that might just be me.) I go outside and test the setup the night before and make sure my devices pair up properly. I've had bad connections to the HC board with the wire harness or
connectors coming loose.

Also, try to get away from anyone else who's HC-06 (05) is nearby. I try and link up in isolation and then walk back to the flight line or whatever. I tried pairing when I wanted to use two separate ground stations to test two different mapping systems on the receive end at once. I scrapped one and used the other one. I later found out I could successfully pair
the second system if I walked out of Bluetooth range of my 1st receive system (Using two LCD's with two different mapping systems one Android one Windows tablet)

Kurt
 
Unfortunately not on my phone. Maybe it's just mine then. When I select OSM as the map provider and try to download th e map it never completes. It either quickly says 100% complete and goes back to the default white screen or it gets hung on something of 12.

Cripes,

Shoot, I'll need to try it again and see what happens with GPS Rocket Locator with OSM maps as last time I tried it, it would download the OSM maps for caching.

I knew about the kinky photomaps provider and went to a high speed download site and got all the photomaps at various zoom levels for the two sites I frequent in the Midwest when they were available. Out of date now but still very usable. For hacked APRS stuff the ArcGIS photomaps are still
usable.

Kurt
 
Sorry to bring this thread back from the dead, but does anyone have the mounting hole spacing for the mini?
 
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