Blog

The 433mHz AM beacon was updated. The  Atmel 328p now has its own PCB instead of the “legs-up-beetle” style of previous versions. The further reduce the size of the unit, the 328p board was placed in a sandwich orientation with the transmitter module.

Despite the small size, the board now has a programming port to enable reprogramming of the module.

Below the 433mHz beacon module in front of an Arduino Uno for size comparison.

The DRA818U radio module is known to produce harmonics at higher frequencies. To avoid problems with other radio equipment a low pass filter was installed in the latest version of the Talky GPS transponder.

To check the efficiency of the filter, a spectrum analysis was performed. Tx power at the ground frequency was unaffected (1 Watt) while the harmonic was reduced from 2.2 milliWatt to 13 microWatt.

Turning the O-ring groove in a 120mm diameter graphite nozzle.

Turn slow (30-45rpm) to avoid dust getting airborne.

The Chiron 3 rocket has two emergency beacons that operate for several days. One in the nose cone and one in a 3d printed shroud on the outside of the coupler section.

An Atmel  328p microprocessor awakes from hibernation every few seconds and generates a tone for 100ms . This low duty-cycle allowes for the extended duration.

STX882 and 328p glued together.

Transmitter module, lipo battery and external connectors in a 3d printed ABS shroud.

3d printer shroud on the outside of the coupler section.

All navigation and communication equipment is mounted inside the nose cone.

Side 1 with the pull-pin switches, 2S lipo for generation of 5V for the camera, a 3d printed housing with voltage converter and 1S lipo for the radio beacon (not yet installed) and the Talky GPS transponder.

Side 2 with two stacked 1S lipo’s and the SMS GPS transponder.

Despite the better performance of the mobius actioncam, the Chiron 3 will be equipped with the trusted #16 808 camera.The CCD was removed from the original housing and is now peeking through a small hole in the nose cone.

The CCD is protected by an aluminium shroud. New enclosures were 3d printed to hold everything in place on the inside.

The camera starts recording automatically when the pull-pin is removed from the nose-cone. For this 5v is provided by a 2S lipo and a voltage converter.

The graphite nozzle is nearly finished. Only the O-ring grooves remain to be cut. Time to clean-up after a messy day in the workshop. Despite the vacuumcleaner, still a lot of dust.

update April 2020: micro-switches (also the ones without lever) have proven to be unreliable for electronics without brown-out protection.  Vibrations can cause short disruptions is the power supply.

3d printed pull-switch array shown here without protective cover.

The Talky GPS transponder uses a dra818U radio module. Unfortunately, this module transmits harmonics at higher frequencies, interfering with other electronics.  Now that the Talky GPS transponder is equipped with a low-pass filter, this problem is solved. This now allows the GPS SMS transponder to work within the vicinity of the Talky GPS.

The GPS SMS transponder transmits coordinates at a 2 minute interval at ground level. When launched, the GPS SMS transponder transmits every 30 seconds.