| The following sketch and instructions should enable just about anyone to make a separable tally light indicator by themselves. The "separable" portion of the design allows the user to remove the video camera quickly and easily from the helmet if required. This also permits less drain on the battery when not in use because the RCA connectors can be disconnected. This system is particularly useful if the user is constantly removing the video camera, whether it be for placement on a belly mount or to film a family event.
What Parts Do I Need?
- One (1) red or green LED that you will be able to see in the worst conditions. Cost = $0.99 each.
- One (1) two lead photo cell (typically a cadmium sulfide photoconductive device that only allows the flow of current when exposed to light). Cost = $2.29 for five (5).
- One (1) 9VDC battery snap connector. Cost = $0.99 for five (5).
- One (1) set of male/female RCA (phono) jacks (2 conductor). Cost = @ $1.30 per set. Note: BNC jacks work well also.
- At least 4 feet of 18 AWG 2-conductor stranded speaker wire (or equivalent). Cost = @ $3.99 for 30 feet.
- One (1) 9VDC battery. Cost = $0.99 each.
- One (optional) resistor - Used to prevent damage to the LED. Most LED's cannot handle 9VDC, therefore a resistor might be necessary. Otherwise, you can use two AA batteries to power the system, but it may not last as long. Cost = $2.29 for a set of 50.
What Tools Do I Need?
- Soldering iron and solder
- Electrical tape
- Wire cutters/splicers
- Multimeter
How Do I Put It All Together?
- Gather all the components and determine the positive (+) and negative (-) sides of each. The "+" side of one component must be connected to the "-" of the next component. The RCA jacks and photo cell do not have distinct sides, and therefore may be installed in any configuration. See the diagram above.
- It is recommended that you test the components of your separable tally light indicator on a breadboard to ensure that they will be installed correctly. If one is not available, you should be able to temporarily connect each component by twisting the various wires together.
- Determine the length of wire that will be necessary from the photo cell to the RCA jack. The photo cell will later be attached to the tally light on your video camera while the RCA jack can be located at the top of the helmet. Typically, a 12 inch piece is required.
- Determine the length of wire between your RCA jack and the battery (typically 12"-16") and between the RCA jack and the LED (typically 16"-18"). The battery and snap connector can be stored inside your helmet while the LED is attached to a ringsight.
- Solder the RCA jack and photo cell connections first and check the effectiveness of your RCA jacks.
- Assemble and solder the battery snap connector and LED and attach to the RCA jack.
- Install the appropriate resistor according to the requirements of your LED, if applicable. See the diagram above.
- Verify that the system was installed correctly by attaching a 9VDC battery and apply light to the photo cell. You should be able to see the LED light up when a large amount of light hits the photo cell. When the photo cell is covered, the LED should be unlit.
- By using a 9VDC battery, you should get at least 1-2 years of service free performance out of this system.
How Do I Attach The Photo Cell To My Tally Light?
- Use a zip tie fed between the two leads on the photo cell to securely attach it to your viewfinder. Use duct tape and/or gaffers tape to seal the photo cell from outside light.
What If I Can't Understand Any Of This?
- Spend $45 (gulp) and buy one....or check out Skytools.
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