The Eggfinder - A Low-Cost GPS/RF Tracking System

KenRico said:

Pulled up the datasheet..it mentions 'requires Requires proximity ground plane' with non metal enclosures.

https://www.mouser.com/ds/2/238/ANT-916-CW-QW_Data_Sheet-10538.pdf

Kenny

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Read about the dipole "Tiger Tail" https://www.hamuniverse.com/htantennamod.html

If you are trying to milk as much range out to the system, you could do a full 1/2 dipole on the transmitter by getting a terminal connector that fits the SMA connector and solder a 3inch wire for a 1/2 wave antenna. With a metal box, the RP-SMA connector has contact with the box that acts as the ground plane.
Do this if your monopole is a 1/2 wave antenna.

If you want more "listening" capability from the receiver, get a patch antenna and Cris makes a suggestion in the documentation of an economical choice. Kurt

The ground planes on the PC board act as the counterpoise for the wire antenna element. It's not ideal, but it works OK. When I was first testing, I got a round piece of tin, put a small hole in it for the antenna wire to pass through, and soldered it to the end of the PC board perpendicular to the antenna. It didn't seem to make any appreciable difference in reception, (it was on an RX prototype), so I didn't pursue it any further.

The commercial 1/4 wave antennas actually have two opposing elements, one is the signal element and the other is grounded. That's why they work better than the wire... they're a "true" 1/4 wave dipole.

cerving said:

The ground planes on the PC board act as the counterpoise for the wire antenna element. It's not ideal, but it works OK. When I was first testing, I got a round piece of tin, put a small hole in it for the antenna wire to pass through, and soldered it to the end of the PC board perpendicular to the antenna. It didn't seem to make any appreciable difference in reception, (it was on an RX prototype), so I didn't pursue it any further.

The commercial 1/4 wave antennas actually have two opposing elements, one is the signal element and the other is grounded. That's why they work better than the wire... they're a "true" 1/4 wave dipole.

Click to expand...

Gotcha..was not worried as Jus Rockets took this antenna to 12.5k ft and got it back - only asked because there are aluminum av bay lids now..but they are annodized.

So sounds like no real benefit to having the short antenna mount to one..I would use the std fg for the other lid

Kenny

KenRico said:

Gotcha..was not worried as Jus Rockets took this antenna to 12.5k ft and got it back - only asked because there are aluminum av bay lids now..but they are annodized.

So sounds like no real benefit to having the short antenna mount to one..I would use the std fg for the other lid

Kenny

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Kenny, Did he have the EF GPS with the 916-CW-HWR-RPS antenna mounted in the ebay with Aluminum lids with all-thread running through it?
Or did he have the aluminum lids drilled to put the antenna outside of the ebay either on a cable or a bulkhead mount? If the antenna was outside the ebay,
I'd expect the Rf range would be fine and the ability of the GPS to receive the satellite signals not impaired much as long as the walls were transparent to the GPS satellites signal. Kurt

Anyone tried this to mount the transmitter in?

https://www.etsy.com/listing/200137112/29mm-smart-altimeter-sled?ref=listing-shop-header-3

ksaves2 said:

Kenny, Did he have the EF GPS with the 916-CW-HWR-RPS antenna mounted in the ebay with Aluminum lids with all-thread running through it?
Or did he have the aluminum lids drilled to put the antenna outside of the ebay either on a cable or a bulkhead mount? If the antenna was outside the ebay,
I'd expect the Rf range would be fine and the ability of the GPS to receive the satellite signals not impaired much as long as the walls were transparent to the GPS satellites signal. Kurt

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Neither he had it and the antenna mounted to a sled that slid into the nosecone (I assume) ..the antenna is connected directly to the TX with no bulkheads in between..

Kenny

You know you guys could just ask. I just tape a piece of 38mm motor tube to the shock cord, inside is a sled with the eggfinder. Both of the bulkheads are wood, the bottom is glued on and the top gets taped.

Old setup with 8" antenna

Just a stupid question/statement...

Would it be nice if the Eggfinder could somehow transmit to an iphone (using whatever radio bands the smartphone is capable of receiving) so it becomes a convenience device for locating your rocket... (or rather, is it possible?)

My rx is connected to a Bluetooth tx so i can use my android phone. Not as direct but it works well.

taiwanluthiers said:

Just a stupid question/statement...

Would it be nice if the Eggfinder could somehow transmit to an iphone (using whatever radio bands the smartphone is capable of receiving) so it becomes a convenience device for locating your rocket... (or rather, is it possible?)

Click to expand...

It would indeed be nice. Unfortunately, Apple has their bluetooth locked up to make such unworkable. If you can find an equivalent circuit to the bluetooth that the LCD unit is designed for that instead uses BluetoothLE then you would be set (other than software). But that would then become feasible at least.

Kirk

The Bluetooth-serial connection is only one obstacle, the other is that IOS doesn't support external GPS's. That's probably the larger of the two... you're not going to able to overcome it by just using a different Bluetooth-serial module than the HC-06.

Since you don't really need the phone part of a smartphone to use it with an Android, you might want to think about picking up an inexpensive Android tablet or a used phone (if you want it to fit in your pocket). Then you can use Bluetooth GPS with any number of nav apps to set the Eggfinder coordinates as a waypoint and navigate from the Android's GPS to that waypoint, and/or track in real-time.

Any suggestions on the tools or method to cut the opening for the LCD screen in the lid of the box Cris supplies ( or any other box) and get a nice clean edge?

Any suggestions on removing the bulkhead on fiberglass nosecones so that they can take the eggdfinder? With an epoxied in welded eye bolt, I can't even simply hole saw out an opening.

You can use a smaller bit and drill a series of holes around the eyebolt washer.. drill the holes side by side . Once the eyebolt is removed you have room to do what you want.

When I did that to my Vindicator nose to fix it..I drilled the outside perimeter and ended up removing the whole bulkhead

Kenny

Drill series of small hole and cut it with abrasive cords like brain surgery...

But it's not brain surgery, it's rocket science!

KenRico said:

You can use a smaller bit and drill a series of holes around the eyebolt washer.. drill the holes side by side . Once the eyebolt is removed you have room to do what you want.

When I did that to my Vindicator nose to fix it..I drilled the outside perimeter and ended up removing the whole bulkhead

Kenny

Click to expand...

That is what I was thinking about. Just looking for verification or a better idea. At least I think I didn't foam these cones. That was a mess removing the foam from a Darkstar mini cone to add a tracking bay to that one.

etoyoc said:

That is what I was thinking about. Just looking for verification or a better idea. At least I think I didn't foam these cones. That was a mess removing the foam from a Darkstar mini cone to add a tracking bay to that one.

Click to expand...

One comment: Make sure the interior of the nosecone can contain the tracker in question before tearing into it. Another alternative would be to simply buy a new nosecone and "fixin's" to make what you need if the current one is too hard to convert. Kurt

The interior has plenty of space, there will be at least 10-11 inches if it isn't foamed. And then it will just be a matter of unfoaming. I will be putting a 24mm tube in for the eggtimer and then foaming around the tube. At this point I am not even sure if I will mess with putting a bulkhead back in.

I built 2 EggFinder Tx boards and the EggFinder LCD today. It was all pretty easy. One of the GPS boards was built with cables for the momentary switch, Yellow LED, and Green LED. I plan to mount those on a small board that I can place near a vent hole in the nose cone shoulder of my Formula 200. It will be paired with a 430MHz BRB BeeLine TX for now so I can have a backup method for locating the rocket. These are nice units and easy to build. I have one more GPS Tx unit to build and I'll probably build that one with the remote switch and LEDs too. I ordered a smaller box for the EggFinder LCD. The one it comes with is silly huge. I plan to mount the box on an L-Com 3dB and/or 9dB Yagi. I can see a few more of these in my future. Thanks for marketing a great product.

I love the Eggfinder!

I have been slowly designing and 3D printing an enclosure for the LCD Receiver. Here is the first half as I need to design the handle that will hold the battery.

The switch positions are not final as I am still waiting for my rocker switch in the mail from china.

Now THAT is a thing of beauty. Excellent job! I'm curious to see how the battery handle thing works. I keep drooling over the 3D-printed things on this site, I'm going to have to buy one of these printers for myself.

I mounted my LCD in a Twin Industries B20-7100, 5.3"x2.9"x1.9" enclosure. I did a pretty terrible job cutting the LCD opening with my rotary cutting blades and so-so on the other holes using my drill press (except for the antenna hole which wound up way off even though I tried to make a template for it :bang: ), I'm tempted to buy another box and try again. For mine I have two switches, two buttons and an external LED. One switch is the battery power switch obviously (using a Turnigy 1800mAh 2S battery I got from HobbyKing velcro'ed to the back lid, converted to clip the two large leads it had and changing to the 2-pin JST header as with my other 2S batteries, I put one of these on the 4xAA box the LCD came with as well), the other is for the speaker (as a mute switch so I don't have to listen to the beeping all the time ). One button is for the on-board "TRS" button obviously (I re-located that physical button to the reset pads for easier access to that when updating), the other is for the LCD backlight (I figured a button instead of a switch so that it couldn't be left on, though this battery could run the thing all day I think). And I removed the green LED from the Hope module and wired up an external green LED for that so that I can see when it's receiving data right at power-up. Everything but the LED is soldered to 2-pin headers so that I can easily disconnect things (since the switches and buttons install from the outside, the LED mounts from the inside so I didn't bother with a header here). Everything pictured was purchased from my local Fry's except for the Eggfinder LCD itself and the battery.



I'm also planning a BT module to connect to the 4-pin header, but using a BLE Nano not an HC-06 so I have some coding to do there first (I can't find any pre-existing UART-to-BT code for this amazingly).

And I just got the shipping notice for my TRS and another RX today (I already have 2 TX's, an RX and the LCD), so I'm looking forward to some more soldering this coming weekend!

Can be done in a vertical fashion if one is so inclined with the aftermarket cable:

https://www.rocketryforum.com/showt...for-Eggfinder-GPS-Tracker&p=739782#post739782

The additional parts are listed in this post:

https://www.rocketryforum.com/showt...-for-Eggtimer-Eggfinder&p=1394589#post1394589

Kurt

Wayco said:

Just got back from the TRA/PHX launch and I had to post up and brag about my last flight. I have been gradually working my way up the motor choices for my 3" carbon fiber Mongoose. Today I flew it on a CTI L1115 to 18,773 ft. The Eggfinder worked flawlessly, despite the estimated 1.7 mach speed. Tracked throughout the flight, and we recovered it using "Rocket Locator". Took less than 15 minutes to recover. I'm using the "rubber duckie" antennas on both the TX and RX.

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Congrats Buddy ! 20k is shakin in its boots cause you are coming for it quickly !

You have the best pit crew also !

Kenny

Wayco said:

Next month will be the M840 long burn, sims to 25k. My sims are pretty close, the L1115 simmed to 18,857.
Sharon says hi, and wishes you could make it to one of our launches.....

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Man what a beautiful flight that was! It's going to be hard to keep up with you and Sharon.

I am thinking I want to get the Eggfinder TRS but from the instructions (without a lot of good pictures too) it seems hard to do, and very easy to mess up. I've haven't really soldered tiny surface mounted parts before so was thinking if this is even a good idea...

For a first time attempt; I would highly suggest you let someone else do it.
It is not a beginner project.
There are allot of parts ( smaller than you can imagine).
I was lucky enough to have another forum member nearby who has assembled the finder and the timer.
Even he was taken by the size and amount of parts.

I helped by building out the Receiver case and lending a hand holding the micro sized pieces.
It took us all day to build the TRS and the LCD / receiver.

I've attached pictures of them.

A magnifying light and a good soldering station are highly recommended.

JD

taiwanluthiers said:

I am thinking I want to get the Eggfinder TRS but from the instructions (without a lot of good pictures too) it seems hard to do, and very easy to mess up. I've haven't really soldered tiny surface mounted parts before so was thinking if this is even a good idea...

Click to expand...

FYI:

It cost about another $150 or so in extras; antennas,
batteries, case, Blutooth module, connectors, etc...


JD

I suppose I could ask the people at AARG if there is someone who could help... but I'm pretty used to high precision stuff (I built guitars for a living). Other than that, it would be nice if someone sold a pre made version of this.