On Thu, 28 Apr 2005, Rob Studdert wrote:
I guess I forgot that. Sleep being different from the first one (standby, no meter) in that the top LCD is also off. Will measure that next time I bring it into school just for completeness.On 28 Apr 2005 at 8:30, Cory Papenfuss wrote:
- You will need the AC adapter for any long-time exposures. I posted awhile back on the voltage/current of the power adapter and someone responded with 6.5V, 3.0A. Since I'm a cheap bastard, I have modified a 6V 1A wall-wart power supply to provide 6.5V. Yes, the 0.5V difference is important... the camera will shut off on long exposures thinking the battery is dead with 6.0V. I measured the current requirements under various conditions as follows (6.5V lab power supply)
0.073A On (standby, light meter inactive) 0.172A On (meter active) 0.253A Meter and LCD active 0.608A Bulb, shutter open 0.450A Noise reduction frame in progress (after Bulb shot) 0.120A SD card write 0.3-1.5A Internal flash recharging.
Good stuff, you didn't happen to measure the sleep mode current did you?
My modification of the power supply basically involved replacing the built-in LM7806 fixed regulator with an LM317 adjustable one. Both are spec'd at 1.0A, but since they're linear they're mostly a heat-limited (average) device they should be able to tolerate some peaky loads of the flash. I don't know why the official supply is spec'd at 3.0A, except that it's a switching supply (and thus more limited by peak current). Since the largest current value that lasts an appreciable time is the bulb mode, I'm planning to benchtest the power supply and make sure it doesn't fry the chip/heatsink after long (10s of minutes) drains of >0.6A.
-Cory
************************************************************************* * Cory Papenfuss * * Electrical Engineering candidate Ph.D. graduate student * * Virginia Polytechnic Institute and State University * *************************************************************************
