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Old Nov 21, 2002, 12:02 PM   #1
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Default Current Input needed to power a dimage 7i

HI

What is the current the DC input ont he camera needs for the camera to start up and power the flash

i'm making a power pack out of a radio controled car battery

The output voltage should be 7.2V
and the resistance of the wire is 0.9 ohm

giving if my theory is right

V = I * R
7.2(V) = I(A) * 0.9(ohm)
move the R under the V to gie the max current.
7.2 / 0.9 = 8A

i don't bellieve the wire is capperble of 8Amps as it really small core.
but does this sound possible?

Many thanks As always.

Tony J
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Old Nov 21, 2002, 12:38 PM   #2
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Default Re: Current Input needed to power a dimage 7i

Quote:
Originally Posted by tonyjobson
HI

What is the current the DC input ont he camera needs for the camera to start up and power the flash
The voltage at the D7i side should be a bit above 6 volts (around 6.1 VDC)

Quote:
Originally Posted by tonyjobson
HI

The output voltage should be 7.2V
and the resistance of the wire is 0.9 ohm

giving if my theory is right

V = I * R
7.2(V) = I(A) * 0.9(ohm)
move the R under the V to gie the max current.
7.2 / 0.9 = 8A

i don't bellieve the wire is capperble of 8Amps as it really small core.
but does this sound possible?
Your equation is quite right only in the case you short the 2 conductors at the end of the cable ( may be 2 x 0.9 ohms if you measured 1 conductor )
(In reality , you have to add the internal resistance of the battery too)
So 8 A does not mean at all that your battery is capable of a such an ouput at rated voltage.
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Old Nov 21, 2002, 3:05 PM   #3
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Default

My bet is you can hook up the 7.2V RC battery right up to the D7's input! Look @ the Minolta external battery pack specs, they are lithium and rated @ 7.2V (ie 8.4v at least when measured initially after removing from the charger).
http://www.bhphotovideo.com/bh3.sph/...ID=F1E0F5E7160

The camera internal switching voltage regulator will then maintain proper voltage to the camera (I'm also willing to wage that it'll also run cooler since since the 'on-time' of the regulator has a smaller duty cycle).

Actually there was an earlier post:
http://www.stevesforums.com/phpBB2/v...257&highlight=
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