[ Thanks to Adam
Palmer for this link. ]
“The camera draws over 350mA@12V and there’s no reason
why I need it permenantly on. I’ve connected one of the Phidget
Kit’s outputs to a simple transistor/resistor/LED circuit, with a
12V supply passing into the transistor’s collector pin, through the
transistor, relay input and resistor. Then I’ve connected the
camera’s power over the relay’s output. The power on and off for
the camera/LED are now through setting the board’s digital output 0
to 1 and 0 respectively. Power consumption with no movement has now
dropped from 1.25A to just under 0.90A. I’ve also put all essential
USB hardware on one usb hub and all optional hardware on another
(USB to TTL adapters, sound adapter) on the other. The optional hub
is also on a relay now on the opposite side of the robot, and this
now reduces idle power consumption from 0.90A to about 0.50A which
I’m happy with.”