The helmet-cam is useful anytime you want video but you don't want to use a hand or second video-person on the project. We use ours to record the designing and building of HowToons projects. It can be an invaluable anlysis and learning tool for rapid prototyping.
photo: Erich Brandeau sports a sweet helmet cam.
Step 1: Parts Layout
Materials List for Waterproof, hands-free video recorder. I've listed the specific parts I used to build a working helmet cam, as well as the basic functional requirements for each part so that alternatives can be explored.
+ Camcorder: Sony HCR-DC32, $300 @ bhphotovideo.com
This model, now discontinued by Sony, has a/v input and LANC remote control capabilities in a miniDV format. When bought new, it also comes with an a/v cable and parts necassary for uploading video to computer for editing. Look for any camcorder with a/v input and LANC in a modestly sized package.
+ Camcorder Case: Pelican 1120 Case, $20.95 @ bhphotovideo.com. These cases come in different sizes, the 1120 works well with the camcorder we spec'd. I would not recommend cheaping out on this step - you want your box to be able to go swimming, in case you fall off of you kite-powered catamaran or something.
+ Waterproof Connectors:
As described later, you will need 3 sets of plugs to connect the outside world to the world inside the pelican case, 1 for the remote, 1 for the microphone, and 1 for the external camera lense.
I use Conxall waterproof connectors (pg. 264 of the current digikey book).
In digikey-part#-speak: order sc1275-ND & sc1264-ND (for lanc), sc1277-ND & sc1266-ND (for video signal), and sc1281-ND & sc1270-ND (for microphone). There are a number of connector combinations that will work. By using three different connector pairs, the connections are mechanically programmed not to get mixed up. Total cost of connectors should hover around 30$.
+ External Camera Lense: 580 Line Sony ExView HAD Helmet Camera (3.6mm), $205.99 from hoyttech.com, and $34.99 for the camera protector (get the protector). A number of bullet cameras are availiable, but this lense is fairly high-res. The 3.6mm lense makes for a decent field of vision, though if I could find a wider angle lense, I would probably use it.
+ Remote Control: LANC remote control, $64.99 from hoyttech.com. LANC comes in a few versions for different cameras. See the website to pick the version for your camera.
+ Microphone: stereo high gain microphone, $28.99 from hoyttech.com
(hoyttech sells the above mentioned parts in packages, too.)
+ Camera Mount: there are a lot of options here. Hoyttech, among others, distributes mounts for a helmet and a headband for no helmet. $10-30
+ Backpack: any backpack should work, though a sports or outdoors oriented pack will fit tighter, minimizing fatigue and distraction. I use a camelbak M.U.L.E., $80 at REI.
+ 12 V Battery (to power mic and video): Easiest to use 8 AA batteries in series; you will definently want rechargables for this operation. I chose to separate the video and audio signals, so I used 2 battery packs. A set of batteries and charges ~$40.
+ Battery Holder: An 8 AA battery pack is overpriced at hoyttech. These are available at radioshack or digikey for well under $10 each. You can also make your own.
+ miniDV Tapes: if you start documenting everything you build the tape-time will fly. I get tapes at 33$ a half-dozen at bestbuy, but that's largely a location convenience ... shop around.
+ Hardrive Space: if you start editing video heavily, you will probably need disc space. Using typical video uploading, 100GB will get you ~7 hours of video. $___.
Step 2: The Information and Power Flow
Building the helmet-cam is not very hard. It's a matter of getting all of the parts together, understanding what connections need to be made, and soldering it down.
Building the helmet-can becomes very hard if you incorrectly interpret the flow of information and power between the components, or if you solder poorly.
When you get all of your parts, assemble the system using the connectors that come with the parts. Particularly if you use all hoyttech parts the connectors should play nice.
+ Plug a battery pack into the camera, and the camera signal (a yellow RCA cable) into the yellow input of the camcorder's a/v cable.
+ Plug the microphone into a battery pack and the stereo audio signal (a red and a white pair of RCA cables) into the matching input of the camcorder's a'v cable.
+ Plug the LANC into the camera.
There is a design choice in this step. You will notice that the hoyt micrphone has two power lines: 12V in and 12V out cable. You may put the camera and the microphone on the same power line (and use a single battery pack). I put the two on seperate power so that I can take the microphone out of the system without disrupting the camera power or doing additional wiring. There may be more elegant ways of doing this, but it works fine.
Play with your sweet-new-setup! With the camcorder "off," you should be able to press the LANC controller and turn on the camera. Once the camera is on, press the LANC again to start recording. The LED on the LANC is green when "on" and not recording and red when "on" and recording. Holding the LANC control turns off the camera, this is indicated by a flashing red LED and then no power. The camcorder sometimes acts confused if you plug and unplug the LANC remote in while the camcorder is on. If you lose video feed, etc. while this happens, power cycle the camcorder.
Step 3: Information and Power Flow, Attaching the Waterproof Connectors.
Now that you've checked the un-hacked system, it is time to replace all of the given connectors with the connxall waterproof connectors. If you aren't an all-star solder-er, take a five minute break, get yourself a bite to eat, and prepare to focus in for a while.
There should be 3 sets of connectors (as listed in the parts layout). In each connector set there is a mounting piece and an end piece. The mounting piece has threads on it, and will eventually go through the wall of the pelican case (shown in a few steps).
The end piece involves some "assembly." There are 3 parts that must be in place over the wires and connector before any soldering should be done. If you solder before adding a piece, you will have to cut your connection and do it over again, so get it right the first time! The hard part here is not how these parts go together, but remembering to do so. (see the attached video on connectors ...to be added soon)
The next few steps are specifics for each of the three connector sets.
(this step is waiting on a picture, video)
Step 4: Wiring the LANC
the LANC has three wires: brown, red, and black, or something. Cut the wire fairly close to the "plug" end of the LANC. The plug side is going to go inside the box. If you don't want to do any planning, leave enough wire behind the plug so that it can reach anywhere inside the pelican box.
Strip both sides of the cut wire, exposing a bit of copper for each of the three wires on both sides of the wire. Solder the LANC connector side ends to the connxall wall mount connector and the LANC button side ends to the connxall wire ends. Just line up red with red, brown with brown, and black with black.
When you are done, it should look something like the picture.
Plug the LANC into the camera and make sure it still works! Then hot-glue your connections to make sure things stay the way they oughta.
Step 5: Wiring the Video Camera
the video camera takes a 12V line and gives a video signal.
Cut and strip the wires coming out of the bullet camera. Cut near the connectors to leave lots of extra wire.
Under the insulation there should be 4 distinct wires. The red and black pair are for power, and the other two (yellow and black or insulated and not insulated ?) are for video.
+ the 12V line +
Cut and strip the ends of a battery pack. Use a multimeter to find the positive (+) and negative (-) lines coming out of the battery pack. Label the lines in some way so that you don't forget. On the connector match the (+) coming out of the battery with the red line on the camera, and the (-) with black.
The camera power lines connect to the connxall end piece, and the battery pack connect to the connxall wall mount piece.
+ the video signal +
The a/v cable should have 3 RCA connectors - red, white, and yellow. The yellow one is for video. Cut the a/v cable at a length that the connection to the camera will fit nicely in the box. The color theme will prevail inside the cut a/v cable.
The video signal (yellow and black pair) from the camera goes on the connxall end piece, and the video signal in the a/v cable goes on the connxall wall mount piece.
The picture shows the a/v cable (on the right) connected to both video and audio connectors. The camera is attached, microphone unpictured.
Step 6: Wiring the Microphone
The microphone has 6 wires that need connecting: stereo audio signal (4), and 12V power (2).
The audio signal cables are yellow and black pairs, the power signal cable is red and black.
Cut and strip the microphone wires close to the connectors, like with the video camera. Remember, the design described here does not use the "12V out" signal. Don't use that wire pair.
+ 12 V Signal +
Find (+) and (-) on the second battery pack. You will connect (+) to the red power line and (-) to the black power line.
The microphone power lines go on the connxall wire end, the battery pack linesgo on the wall mount.
+ Audio Signal +
The red and white pairs of wire on the a/v cable should already be stripped. Pair the red cables with one of the yellow and black audio signals coming out of the microphone, and pair the white ones with the other yellow and black pair.
There's too many uses of the word pair here: the stereo signal is a pair of paired wires. Connect the wires so that each black cable from the microphone goes to an "unshielded" wire of the a/v cable, and each yellow cable goes to a shielded one. It is ok to put the yellows both on the unshielded and the blacks on shielded, but make it continuous one way or the other.
watch the short video on this, too.
Step 7: Putting It All in the Box
Now, all of your waterproof connectors should be attached and the entire system should be electronically functional.
The connxall mount pieces will be attached through a wall in the pelican case, with camcorder and batteries inside, and microphone, remote, and camera outside.
I used a 5/8" endmill to cut holes in the pelican box. It seemed sensible to put the connectors on a side wall, though make sure everything will fit (and wires are long enough) before cutting any holes. Nothing ruins a water proof case like holes. After a bit of planning, I put a mark on the outside wall where I wanted my hole and then eyeballed it; the placement does not have to be very precise, but it should be logical.
Take the nuts off the connector. The rubber washer that comes with the mount piece goes on the inside wall. Insert the connector, and tighten the nut on it. You'll want a 13/16" wrench for the tightening.
If the holes weren't too sloppy and the connector is tight enough, this case is now waterproof. Take out the expensive stuff and submerge your box to convince yourself. If the box is not waterproof, go through the steps again, and maybe seal the holes with hot glue or something until it's actually waterproof.
Step 8: Mount the External Camera; Play With Your Setup
you should now have all of the pieces in place for a hands-free helmet cam.
Where to put the box and how to mount the external camera is another science altogether. It seems everyone has their own style and needs when it comes to the head (or other body part) mount. both hoyttech and b&h video have some good mounts.
microphone placement depends on application. If you're going to be in a windy environment, concealing the microphone tips from wind is important. If you're taking footage in the shop, you just want the microphones not in the way. The REI backpack has really conveniently placed loops on the shoulder strap for putting your microphones in. (see picture)
The other picture in this step is Erich jumping on the trampoline, reading a text message, and taking video footage of the whole ordeal. One might be able to do this with a regular camcorder, but probably not as awesomely!