Friday, November 02, 2007
Power for TIS DMK, DBK or DFK
DMK camera uses standard 6-pin 1394 power to connect to the computer, these type of cable will also carry 12V DC for the DMK. However, some notebook PC, despite having 6-pin ports, might not deliver power if they're in battery mode. Therefore, you will need something else to provide power for the DMK.
Normally desktop PC, or laptop PC in A/C power mode, will provide power through a 6-pin 1394 port, in that case, you don't need a seperate power source.
Another case is those notebook PC with only 4-pin 1394, this kind of port also will not provide power.
I found a 1394 hubs with power input is the best solution. The above 1394 hubs is acquired from ebay, it's inexpensive, light weight and compact. It has a small 12V DC in plug, with center positive just like most devices do.
The battery box can be found in many electronic shops, they carry 8 AA batteries. And the output terminal is those "9V" style connector as show above.
Since DMK cameras are rated at 8-30V DC, we can provide anything from 8-30V to the 1394 hubs, but to play safe, we should better stay around 12V DC which is the normimal value for 1394 standard. For the 8 AA battery box, it gives us two possible options:-
1. 8 AA standard akaline battery: 8 * 1.5V = 12V
2. 8 AA rechargeable battery: 8 * 1.2V = 9.6V
I have tried both options and they both work without problem. I even tried to power two cameras at once, one DMK 31AF03.AS and another one DBK 21AF04.AS, they work flawlessly.
Suppose I use 8 AA 2300mmAh rechargeable, the batter box can provide power for virtually a whole night of operation for a single camera. I've connected the battery box to the 1394 hubs with a simple DIY cable, but I believe such a cable can be acquired off the shelf easily.
A powered hubs has an advantage to let you connect two cameras, or even more to the same PC. IC Capture supports multiple cameras, but be sure to consider 1394 bandwidth capacity, for example, my DMK31AF03.AS when running at full 1024*768*30 fps, it will take up all bandwidth virtually so that you probably cannot use another device at the same time.
Apart from the above solution, you may also buy a 1394 Y-cable with power input from TIS, I didn't try it but I think it's simplest.
Finally, I have even tried to use a third option, it's to connect the 1394 hubs to a powered 1394 connection to get power from that connection. For example, my notebook PC has a 4-pin port which does not provide power, and so I also connect my desktop PC to the same hubs with a 6-pin to 6-pin cable, and then I connect my DMK to the same hubs, and everyone got power! Another bonus of this setup is that, you got 1394 networking between your desktop PC and your notebook PC.