On 28 Apr 2005 at 9:46, Cory Papenfuss 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. > > 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.
I assume that your bench supply doesn't have a peak recording ammeter? I would guess that through each of the actions or combinations of them there would be some peak that may potentially catastrophically overload an underrated switching PSU hence the 3A margin. An LM317T in (TO-220) should be able to cope with 1.5A continuous leads and up to 3A instantaneous peaks without too much fuss as as long as it's got a suitably rated sink attached, and so long as the input to output differential is sufficient under load. Good luck and don't burn your fingers testing the Vreg :-) Cheers, Rob Studdert HURSTVILLE AUSTRALIA Tel +61-2-9554-4110 UTC(GMT) +10 Hours [EMAIL PROTECTED] http://members.ozemail.com.au/~distudio/publications/ Pentax user since 1986, PDMLer since 1998
