The short-circuit current of a fresh AA cell is probably almost 10 Amps. It can definitely source more than 1.5 amps with a voltage well above 1 V. I don't know how many LEDs are in this tapestry so it is difficult for me to judge how much current I would expect it to draw, both on average and in terms of peak pulse value. How long do the AA cells typically last while powering this? By the way, I think that alkaline batteries are pretty amazing. I have measured the short circuit current of a Duracell alkaline D cell at something like 20 Amps and if I remember correctly, it sustained more than 10 Amps for several minutes. Even more amazing, a D cell is about a 13 Amp-hour battery! Compare the size of 8 D cells to a 12V, 13 Amp-hour lead acid battery. Of course, the lead acid battery is rechargeable but still, I think the volumetric and gravimetric energy and power density of alkaline cells is impressive. Sean On Thu, Jan 24, 2013 at 3:19 PM, William Bulley wrote: > According to Bob Ammerman on Thu, 01/24/13 at 14= :59: >> >> Just a dumb question: are we sure that the power supply has the "oomf" t= o >> drive the tapestry? Maybe it is being loaded too much resulting in volta= ge >> drop. Perhaps it is even shutting down due to overcurrent or thermally? >> >> Should check voltage across the supply under load! > > I was most worried about the "oomf" factor from day one. :-) > > The wall wart in question (4.5 VDC) has "1.5 Amps" listed on the label. > > According to Wikipedia: > > "An AA-sized alkaline battery might have an effective capacity > of 3000 mAh at low drain, but at a load of 1 ampere, which is > common for digital cameras, the capacity could be as little as 700 mAh= .." > > and: > > "The nominal voltage of a fresh alkaline cell is 1.5 V." > > Maybe the wall wart lacks the "oomf" after all... :-( > > Regards, > > web... > > -- > William Bulley Email: web@umich.edu > > 72 characters width template ----------------------------------------->| > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .