On 15/12/2010 17:25, V G wrote: > On Wed, Dec 15, 2010 at 8:17 AM, Olin Lathropw= rote: > >> I guess I missed something in the flurry of messages, but I thought you >> were >> now using a switcher so the input voltage above 5.5V is not a problem, i= n >> fact desirable. Certainly a switcher can be set to deliver pretty close= to >> 5V out, so what's 5.5V got to do with anything now? > > The switching supply that I'm using, > http://focus.ti.com/docs/prod/folders/print/tps63020.html, has only a 1.8= - > 5.5 volt input range. Wrong kind. That's for running off 2 x AA or one LiPoly. For 5V and 1A that would=20 not be a good idea. You want the OTHER kind of switcher that reduces the voltage, always.=20 Using a higher voltage makes it easier to recharge from 12V or Car and=20 gives less losses generally as diode drops or IxI xR loss is lower.=20 Double input volts then nearly 1/2 current. 2 x AA or 2 X C input volts,=20 gives twice current, Regarding D cells. In theory they exist, In practice very very expensive or really C cells=20 in a bigger box. AA 1800mAH to 2200mA 2500mAH Higher seem to be optimistic and self=20 discharge fast. C 3000mAH to 3,500mAH. The 4000mAH seem to be related to 2700mAH=20 fantasy AA cells I use 18 x C NiMH to replace 19 x D NiCd and it's only slightly less=20 capacity than original. The NiMH seem to be slightly more volts. Hence=20 18 rather than 19. It's for a 24V military man Pack. About 100mA to=20 250mA on receive and about 3A to 5A peak on transmit. --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .