- by Ned Nassif)
Having always wanted to add
functionality to my rockets, I decided that adding a camera would be a great
start. I scoured the internet via Rocketry Online, as well as directing my
browser to any camera link mentioned in RMR. It seemed a lot of rocketeers had
used the circuit on Rob Nee's AYUCR page. It seemed simple enough, so I was off
to the races. I had a Minolta Freedom 50 camera that my wife had discarded and
replaced because she was having problems with it. It needed minor attention and
soon found itself on the operating table. What I had failed to realize was that
this camera had a mechanical shutter button. DOH! I had already started the
circuit and was having problems getting it to work right. (note: Rob was very
helpful via several email exchanges) In my searching for another way to operate
the camera, I stumbled upon a servo testing circuit that seemed to be what I
So it was back to the electronics store for more components. I was going to use
a servo to somehow press the shutter button on my camera......
Then a couple of months ago, Ray Dunakin posted to the
ROL forums that he had just posted some new pictures to his website. After
seeing some of the best inflight pictures I have ever seen, I fired off an
email to him to find out how he operated his camera. He replied in short time
with a nice description and a picture of his "capsule". In his note
he mentioned that he used a servo and cam to drive his camera. From the picture
that he sent me, the setup seemed pretty straight forward.
Ray Dunakin's Camera
In scrounging around my house for the materials to build
the pod, I decided that for my 1st attempt I would not use the mirror for
downward boost shots, but instead have the camera looking straight out upon
boost and face down upon descent. This was due to the fact that I had a little
over a week till our next club launch and I wanted it to be functional by
The capsule is made of board,
plywood, a coupler the size of the booster, some foam, and surplus 3.9" BT
. I used 5min. epoxy for my glue joints with CA here and there. I also opted to
glass the entire pod.
The first step is to measure your camera
dimensions and make sure that you calculate for the side pieces. You want to
have a snug fit to keep the camera from shifting, yet leave a little room on
the right side for the lever you will make for the shutter (approx
1/4-1/2"). What you are doing is making a boxed rectangle into which your
camera, servo, batteries, and any circuits you choose will fit. See
diagram below. It goes together supprisingly fast. For the top of the
pod, cut a piece (semicircle) of body tube of the appropriate depth and glue to
the back and sides at the top of the camera compartment. Cut out an area of the
front piece to allow for the lens and light meter to be fully exposed.
I glued a 1" piece of BT to the bottom
section, then used 3/4" foam to form my transition. The coupler was
attached using a piece of allthread to facilitate my altimeter. You can skip
that and glue the coupler inside the 1" BT if you want.
What you are trying to accomplish
is to have the servo arm rotate 360 degrees continually. You will have to take
the servo apart and remove the "stops" which prevent this. NOTE:
While you're in there, if you choose the simpler method of powering the servo,
remove circuit board and solder black and red wires directly to the motor. Run
these wires out of the servo case when you put it back together.
With your camera in position in the
pod, glue a piece of plywood that will run from side to side just in front of
the camera. Make sure that you can easily install and remove the camera before
you glue it in (see diagram). You will also need to make a sturdy base for the
servo. I traced a line around the servo and cut out the hole that will support
the base of the servo. I also glued 2 vertical braces that extend to the top of
the servo. You can screw a piece of wood to the top of the 2 supports or use
velcro to secure the servo in place. Cut a piece of hardwood block or laminate
2 pieces of plywood to make the block or the cam fulcrum to be screwed into. I
used basic radio control items for the fulcrum and lever. The lever that
connects the cam to the fulcrum is 4-40 allthread that is used for push rods.
Both the fulcrum and connecter to the servo arm are plastic swivel ball links
with brass inserts and threaded ends. I used a 4-40 threaded screw eye to
connect the cam setup to the lever. Use a 4-40 nut on the allthread to retain
the screw eye.
Depending on your setup, you may
have to build up the area where the lever makes contact with the shutter
I secured the front piece to the
unit with electrical tape. On future pods I will use some strips of plywood or
hardwood blocks around the perimeter to facilitate small screws. I used foam
padding in the pod and where the front makes contact with the camera to make
On my first flight, the servo was
driven by the circuit that I mentioned earlier. It used potentiometers which
enabled me to adjust the rotation of the servo. It worked well, but when trying
to add a timer to it to delay the activation till apogee, I must have fried the
electronics in the servo, because it no longer would receive the pulses from
the circuit. So, in another email to Ray, I asked him how he drove his servo.
He said he used 2 "AA" batteries wired directly to the servo motor.
When I read this, I laughed almost convulsively at all of the hours of head
scratching, fiddling and 10+ email exchanges with Doug Sams, trying to get my
fancy circuit to work right. Well, the second outing used the 2 "AA"
batteries and everything worked fine. It gives the servo very close to 1
rotation per second, which is what I was looking for. YMMV. Use whatever method
of servo operation your abilities allow. To start the servo, you can either
flip a switch prior to launch, or make a switch that is actuated at liftoff.
Don't be afraid to ask for help. I met some very nice rocket folk in my
journey, who were very willing to help me out.
|1 standard servo
|1 sheet foamcore board
|2 plastic swivel ball links
|1 length 4-40 allthread
|screw eye 4-40 thread (pkg)
|1/8" aircraft plywood
|misc. wire, batteries, switches
|Total (less camera, foam)
* You may have some of this stuff lying
around or use substitutes