Build me an Eggtimer Ion, yes. First of a bunch of ET kits to build.

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Kim's Rocketeer
TRF Supporter
Jan 20, 2011
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The ION is just a WiFi enabled flight logger. No outputs for deploying or anything. And it is not like the Jolly Logic stuff in that it can not sit in the body tube (or so I assume). Nor is it powered internally - which sort of sucks as that makes the Pnut, Adept Altimeter One, and the JL things, a lot more convenient. However it will (barely) fit in a BT-50 payload tube with a 100 to 300 mah LiPo. I am building three. So I don't care if 100mah is good for 90 minutes at best. Unless I am launching at ROC, 90 minutes should be fine. :D :p And one can charge small LiPo bats almost anywhere. I like to throw altimeters in almost every flight. Really helps validate the sims. And its just fun. But I still have to pick... payload bay or no payload bay to figure out which goes up.

I replaced the tiny JST with the next up tiny JST. I have an adapter cable to go from super tiny, whatever its called, to just sort of tiny, whatever its called, connector. Its an old man thing. Cause I find batteries are all over the map when it comes to connectors. Most of the 400mah batteries I found used 'molex' connectors. Easy enough to cut off (BE CAREFUL) and replace.

Anyway the IONs are to drop into a payload bay with a battery strapped to its back (isolated by foam tape, don't want no punctures!). No way am I making a 'sled' for it. That's way too much work. It is not as small as a Jolly Logic Altimeter 1, 2 or 3, nor my beloved Adept Altimeter One's, nor the Perfectflite PNut, but its WiFi and cool, and is cheaper at $20 than all those I just mentioned. And I can brag I built it. :)

I assembled mine using a relatively cheap hot air rework station and a 'Pencil' soldering iron with a pointy tip. I did not use the supplied solder. I found it hard to use at any temp. The roll of .020 I got from Adafruit seemed to work a lot better. I have practiced using the hot air station using SMD practice kits from Amazon for like $5 a piece.

I must admit, using resistor leads to fake a chip socket was pretty brilliant. I have several ESP boards. Most are the more modern 32 bit variety. But I have to hand it to Chris at ET, another really nice job!

One thing I have not read in the docs. My ION beeps FOUR short beeps. Then a long one. Not three. Then self arms in 60 seconds, or is there to be dealt with on my phone via WiFi. Unless I missed it, I do not know what 4 instead of 3 means.

Again for $20 and less than 2 hours work, Chris' stuff is just the best.


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Four beeps instead of three, as far as I can tell, means there is a typo in the manual. There are a few others.

I've built a couple of these and have flown them some. I agree on the value proposition.

Like you, I like to put an altimeter in just about everything I fly.
What I dont get, is all my LiPo's and such are the opposite polarity of the ION connector. No matter. I ripped the connector out and soldered a pigtail with a reversed connector. Works fine. I looked at the recommended 400mah Sparkfun battery and shoor nuf honey child, it is wired as the ION is. Another reason why all connections IMO should be screw terminals. I'd not have to deal with creating custom pigtails. JMO
I just put the sockets on the IONs (I've just finished a third one today) in the other way so they matched the chargers I already had. I then pulled and swapped the pins in the connectors on the 1s LiPolys I ordered from Cris with the first two IONs to make them match that polarity.

Cris notes in the instructions that LiPolys sold for the RC market are wired the other way, and so to watch out.

I do have one LiPoly around that I got from Adafruit that goes with the Arduino-based altimeter that Will Marchant and Bruce Canino presented at NARCON back at the end of January (I assembled one of them). I'm going to have to be careful with that cell as it's not so easy to swap the connectors on the boards from Adafruit as it is when you assemble your own, so I have to have separate pigtail to charge it.

Screw terminals are heavy. I'm mostly an LPR guy and the ION is the heaviest altimeter of any that I currently use. But then, when you assemble it yourself, you have choices there, too. The trick would be getting the necessary terminal bit to install on the ION...I wouldn't know where to even look to get one. But you might know.
Again for $20 and less than 2 hours work, Chris' stuff is just the best.

Agree 100%

I have become a very big fan of Cris' products and will continue to buy his stuff. I have a full compliment of MissileWorks and Raven as well but the small size, simplicity, LiPo compatibility, and cost of the stuff Cris is putting out really has shifted my buying as of late. With the cost of motors going up, trying to find a small way to cut costs makes sense. Cris' stuff fills that gap very nicely.
I took the socket off of the ION. I soldered a pigtail on the pads ending in a JST-<something or another - next size up - XH 2.54?> instead and hot glued the around the wires on the board to not bend/break them. I bought 4pcs of GNB 380mah 1S LiPo's. Took off the Molex(?) connector (one lead at a time of course!) and added the opposite JST on with the correct polarity. The are long and slender. Course the ION wont fit anything smaller than Bt-50. But I have a Pnut or a JL Altimeter one for that.