From: Daniel S. <de...@pm...> - 2008-11-14 18:47:54
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You are actually throwing away a lot of power doing this with a linear regulator. These days you can get simple switchers as drop-in replacements for linear 3-terminal regulators (without the need for external inductors). They have around 90% efficiency, and provide high current output with little power dissipation. This is a much abetter way to go with battery-powered applications. Here is one I have used recently: http://www.alliedelec.com/Images/Products/Datasheets/394-0052.pdf At 09:48 AM 11/14/2008, you wrote: >I have already done the mod that Dave suggested. The battery that I am using >is a 14.4V 2500mAh Roomba APS battery pack. Ideally I want to run it through >the Roomba, but for now I'm running directly from the battery for debugging. >I'll run over to our ECE shop at 1:00 when they open again to see if I can >get the caps that you suggested and I'll let you know how it works. > >Thanks, >-Russ Morin > > >m_ahlenius wrote: > > > > Hey, > > > > let me change that electrolytic cap size. Actually I'd bump it up to a > > larger size - more like 100 uF or 200 uF or so. These new ones are > > quite small. > > > > 'mark > > > > Mark Ahlenius wrote: > >> Hi Russell, > >> > >> what I would do is to go over to Radio Shack or your electronics parts > >> supplier and pick up a small electrolytic capacitor - say 25 to 50 micro > >> farads (uF) at at least 20 vDC which is the working voltage (greater if > >> fine). Also get a small 0.1 uF decoupling cap as well with the same > >> voltage range.. Both are quite cheap > >> > >> The decoupling cap usually does not have polarity, so just solder it > >> from your 7805 power output to ground. The electrolytic will be > >> polarized, so also attach it from the power output to ground, but make > >> sure the + side of the cap goes to your power output pin. Both of these > >> should be as close as possible to the gumstix board. > >> > >> Let us know if this solves your problem. BTW - what is your battery > >> size and voltage? These gumstix devices are power hungry and if you > >> don't have enough battery current - that will be your problem. > >> > >> 'mark > >> > >> RussellMorin wrote: > >> > >>> Mark, > >>> > >>> Currently I just have battery power going into the L7805 and the > >>> regulated > >>> power coming out. I don't know enough electrical engineering to have > >>> tried > >>> adding caps. I hooked a DVM up to the leads and noticed that the voltage > >>> starts to drop off from 5.02 Volts down to 4.83 and dropping. How should > >>> I > >>> configure my circuit to stop this from happening? > >>> > >>> Thanks, > >>> -Russell > >>> > >>> > >>> m_ahlenius wrote: > >>> > >>> > >>>> Russell, > >>>> > >>>> out of curiousity, do you have a decent sized cap as well as a small > >>>> decoupling cap on the output of the L7805? You might put scope or DVM > >>>> on the power output and see if you can detect a dip in voltage. I do > >>>> recall that the Wifi does suck down some power. > >>>> > >>>> best, > >>>> > >>>> 'mark > >>>> > >>>> RussellMorin wrote: > >>>> > >>>> > >>>>> Dave, > >>>>> > >>>>> I am having a similar resetting problem. I have a > >>>>> Connex200xm/Robostix/Wifistix setup running Buildroot 1629. It runs > >>>>> perfectly fine on a Gumstix power supply, but I'm trying to disconnect > >>>>> my > >>>>> robot from the wall. I'm getting power to the stack through a L7805CV > >>>>> regulator to give it 5V and up to 1.5 amps. Since the wall wart for > >>>>> the > >>>>> Gumstix is rated for 5V at 1 amp this should be fine. > >>>>> > >>>>> Right about when the Wifistix starts to kick in the stack reboots and > >>>>> goes > >>>>> into an infinite reset loop. Are there any mods besides the pullup > >>>>> resistor > >>>>> mod that I could do to make this work? > >>>>> > >>>>> Thanks, > >>>>> -Russ Morin > >>>>> > >>>>> Dave Hylands wrote: > >>>>> > >>>>> > >>>>> > >>>>>> Hi Jostein, > >>>>>> > >>>>>> > >>>>>> > >>>>>> > >>>>>>> I received my Gumstix and Robostix two weeks ago for my project this > >>>>>>> fall > >>>>>>> at > >>>>>>> the Norwegian University for Science and Technology (NTNU). The > >>>>>>> first > >>>>>>> thing > >>>>>>> I noticed was the weird dents on top of one of the chips on the > >>>>>>> Verdex > >>>>>>> XL6P. > >>>>>>> I don't know if they are normal, so I've attached an image of it. > >>>>>>> > >>>>>>> > >>>>>>> > >>>>>> I think I see the dent that you're talking about. It really depends > >>>>>> on > >>>>>> how it was created. > >>>>>> > >>>>>> > >>>>>> > >>>>>> > >>>>>>> The other > >>>>>>> image shows how I've connected the Verdex to my computer. The Verdex > >>>>>>> is > >>>>>>> plugged into the Robostix, and the Verdex FFUART available from the > >>>>>>> Robostix > >>>>>>> is connected to my Atmel STK500 - which also powers the board with > >>>>>>> +5V. > >>>>>>> The > >>>>>>> STK500 contains a level converter and RS232 out which lets me > >>>>>>> connect > >>>>>>> it > >>>>>>> to > >>>>>>> my computer. > >>>>>>> Using kermit I can connect to the Verdex, and at first it seems ok, > >>>>>>> but > >>>>>>> then > >>>>>>> it starts resetting. > >>>>>>> > >>>>>>> > >>>>>>> > >>>>>> That's not good. If you have a Wifi chip, then the resetting is > >>>>>> normal. If you don't, then I would be inclined to return the gumstix > >>>>>> for RMA. > >>>>>> > >>>>>> -- > >>>>>> Dave Hylands > >>>>>> Shuswap, BC, Canada > >>>>>> http://www.DaveHylands.com/ > >>>>>> > >>>>>> > ------------------------------------------------------------------------- > >>>>>> This SF.Net email is sponsored by the Moblin Your Move Developer's > >>>>>> challenge > >>>>>> Build the coolest Linux based applications with Moblin SDK & win > >>>>>> great > >>>>>> prizes > >>>>>> Grand prize is a trip for two to an Open Source event anywhere in the > >>>>>> world > >>>>>> http://moblin-contest.org/redirect.php?banner_id=100&url=/ > >>>>>> _______________________________________________ > >>>>>> gumstix-users mailing list > >>>>>> gum...@li... > >>>>>> https://lists.sourceforge.net/lists/listinfo/gumstix-users > >>>>>> > >>>>>> > >>>>>> > >>>>>> > >>>>>> > >>>>> > >>>>> > >>>>> > >>>> > ------------------------------------------------------------------------- > >>>> This SF.Net email is sponsored by the Moblin Your Move Developer's > >>>> challenge > >>>> Build the coolest Linux based applications with Moblin SDK & win great > >>>> prizes > >>>> Grand prize is a trip for two to an Open Source event anywhere in the > >>>> world > >>>> http://moblin-contest.org/redirect.php?banner_id=100&url=/ > >>>> _______________________________________________ > >>>> gumstix-users mailing list > >>>> gum...@li... > >>>> https://lists.sourceforge.net/lists/listinfo/gumstix-users > >>>> > >>>> > >>>> > >>>> > >>> > >>> > >> > >> > >> ------------------------------------------------------------------------- > >> This SF.Net email is sponsored by the Moblin Your Move Developer's > >> challenge > >> Build the coolest Linux based applications with Moblin SDK & win great > >> prizes > >> Grand prize is a trip for two to an Open Source event anywhere in the > >> world > >> http://moblin-contest.org/redirect.php?banner_id=100&url=/ > >> _______________________________________________ > >> gumstix-users mailing list > >> gum...@li... > >> https://lists.sourceforge.net/lists/listinfo/gumstix-users > >> > >> > > > > > > ------------------------------------------------------------------------- > > This SF.Net email is sponsored by the Moblin Your Move Developer's > > challenge > > Build the coolest Linux based applications with Moblin SDK & win great > > prizes > > Grand prize is a trip for two to an Open Source event anywhere in the > > world > > http://moblin-contest.org/redirect.php?banner_id=100&url=/ > > _______________________________________________ > > gumstix-users mailing list > > gum...@li... > > https://lists.sourceforge.net/lists/listinfo/gumstix-users > > > > > >-- >View this message in context: >http://www.nabble.com/My-Gumstix-keeps-resetting-tp19638258p20505292.html >Sent from the Gumstix mailing list archive at Nabble.com. > > >------------------------------------------------------------------------- >This SF.Net email is sponsored by the Moblin Your Move Developer's challenge >Build the coolest Linux based applications with Moblin SDK & win great prizes >Grand prize is a trip for two to an Open Source event anywhere in the world >http://moblin-contest.org/redirect.php?banner_id=100&url=/ >_______________________________________________ >gumstix-users mailing list >gum...@li... >https://lists.sourceforge.net/lists/listinfo/gumstix-users **************************************************************************** The lame man who keeps the right road outstrips the runner who takes a wrong one. The more active and swift the latter is, the further he will go astray. -Francis Bacon, essayist, philosopher, and statesman (1561-1626) **************************************************************************** Daniel E. Sampson Instrument Engineer A232 Earth and Marine Sciences University of California Santa Cruz, CA 95064 dsa...@es... (831) 459-4992 office (831) 359-9075 cell (831) 459-3074 FAX **************************************************** |