The basic ingredients are shown above:
A commercial 2.4GHz microwave wireless audio/video transmitter and receiver; an Aerotech ARCAS rocket kit and (below) a colour CCD bullet camera. Creating a lightweight system and suitable airframe for black powder has been deferred while the microwave link system is explored and debugged.
The image above shows (from left to right):
The 12V powered AV receiver, an 18mm motor for scale, a bullet or lipstick style security camera in a metal body and the 12V powered AV transmitter still in it's metal case.
Clearly, boosting the camera, transmitter and a 12V power source using black powder motors would represent a challenge due to weight and bulk.
|In order to fit the transmitter inside the ARCAS body tube the circuit board was removed from the metal casing. It was necessary to cut a small slot in the case using a Dremel cutting disc mounted in an Arlec SuperTool to enable the antenna to be freed from the case. I did not want to get involved in de-soldering the delicate antenna wire from the circuit board.|
|Rather than use a plug and socket arrangement for power to the transmitter board a 12V line was soldered directly to the board for improved reliability during flight. The ground connection is made via the regulator heat sink tab (see below).|
The image above shows the system configuration:
The black RCA audio plug and red video RCA plug are disconnected for clarity.
The TX board has been mounted to a piece of modelling ply using nylon bolts and standoffs. The red 12V line shown in the preceding image above can be seen connected to the 12V bus.
Camera power and ground are also connected on this side of the assembly. The video output from the camera is connected to the red RCA plug along with video ground from the central ground point.
At the extreme left of the piece of ply is an electret microphone insert to pick up essential on board audio. The mic connects to an audio preamplifier board on the other side of the ply (see below).
Mounted on the other side of the ply is a kit audio pre-amplifier from Dick Smith Electronics and the power supply.
The 12 volt power supply consists of four 3V EL123(CR123) Lithium cells in series mounted inside two short lengths of Apogee Components body tube.|
These cells are quite expensive but appeared to offer high energy density and low weight.
The power and microphone connection to the pre-amp board can be clearly seen.
|Removed from the case the board just fits inside the ARCAS body tube. It needs to sit deeply enough down inside the body tube so as not to foul the long shoulder of the ARCAS nosecone.|
The camera and antenna are positioned along the axis of the body tube.
The nacelle is carved from a solid block of balsa and secured via a long nylon bolt. Evidence of the shock absorbing role of the nacelle is obvious from the field repairs.