I'm a big fan of Eggtimer products, I have several quark altimeters I use frequently and a bunch of eggfinders (5 I think including mini's and TRS's), I use one in nearly every flight. Big thanks to Cris for supplying such great products at great prices! But... I also love to tinker with things and can't leave well enough alone. I got this idea in my head to make my own transmitter. I wanted a transmitter with an integrated battery, USB charger, and a small enough size it would fit in most rockets. This is what I came up with. I just put it together last week and started testing stuff, but I was pleasantly surprised when it fired up, got a GPS lock and started transmitting GPS data. YAY! It works with my existing Eggfinder receivers as expected too! It uses the same transmitter module as the eggfinder and the same method of operation, it's simple and it works well. I did try out a new type of GPS module with a teeny tiny chip antenna. I was worried about that but it seems to perform really well so far. Here are the details - 16mm x 76mm PCB, about 10mm thick complete with battery and OpenLog (fits inside 18mm tube) - Push button on/off that requires a 1sec hold to prevent accidental presses. - integrated 300mah 1S lipo (~2.5 hour runtime) - integrated USB charger with LED's (green charging/red done) - blue power LED cuz I love blue LED's. - Orange 3D Fix LED, steady on when there is a 3D fix. - OpenLog micro SD card for logging flight data. - RP-SMA antenna mount, or wire antenna. - backup power to GPS module to remember previous satellites for quick lock - Off state current should be under 16 micro amps so it won't drain the battery when its off. I have some connectors coming for the battery, a stubby antenna, and some clear shrink tube to go over everything. already have a list of things to fix if I make more PCB's lol.