## Re: [Gumstix-users] power plug dimensions?

 Re: [Gumstix-users] power plug dimensions? From: Dave Hylands - 2005-01-19 17:12:51 ```Hi Arthur, On Wed, 19 Jan 2005 16:39:41 +0000, Arthur Magill wrote: > > > > The jack on the board has a built-in switch, and I wired up my battery > > connector to take advantage of it. This causes the battery to be > > disconnected with the power jack is plugged in. > > > > Dave, > > Can you 'hot swap' the power, or does that make the gumstix reset? I > guess there must be a solution, using a capacitor to bridge the power > while the switch flips? That's a very good question. I'll have to try it when I get home tonight. Using a capacitor would probably work. I did a quick calculation (maybe somebody else can check this since analog electronics isn't my strong suit). If we assume that the gumstix draws 200 ma at 5v, then we get an effective resistance of 25 ohms. t = RC, so C = t/R. If we set t to be 1 second, then we need C = 1/25 = 0.04 F (or 40,000 uF). I know you can some small supercaps, like this one: http://www.solarbotics.com/products/index.php?scdfa-250100084-viewDetail-productzq3808zq4categoryzq34=true I have one these at home - I'll have to see if it fits in the case. -- Dave Hylands Vancouver, BC, Canada http://www.DaveHylands.com/ ```

 Re: [Gumstix-users] power plug dimensions? From: Chris Radcliff - 2005-01-19 04:50:33 ```Gordon Kruberg wrote: > Sorry, I will really try to get more info like this posted! > http://www.gumstix.org/tikiwiki/tiki-index.php?page=POWER_JACK Understood. It's not like you have anything else to do. ;) Thanks! The link led me to a document with the dimensions of the power jack. (Dave's dimensions were very close, 0.65mm for the pin.) Unfortunately, DigiKey doesn't carry it any longer and doesn't list a corresponding power plug (female end), which is what I need to figure out. I'll keep looking. Dave Hylands wrote: > I've powerd my gumstix/waysmall using 3 AA-NiMH batteries. I krazy > glued a connector on my waysmall board and soldered it to the back of > the normal power jack. Thanks for the suggestion. Is that preferable to using the existing jack? I was envisioning something like: power jack <= power plug header <===cable=== battery holder ...which hopefully would get around the need to solder anything to the board. I'm a soldering novice, so I'd prefer to make my mistakes on the power plug. ;) Thanks again, ~chris ```
 RE: [Gumstix-users] power plug dimensions? From: Basham, Richard R - 2005-01-20 05:28:11 ```I thought I would help out with the calculation for the capacitor decay. There is a slight problem with this calculation as tau, the time constant defined by R & C, is the time it takes for the capacitor to naturally discharge to approximately 37% of its original voltage once the power source is removed. After one second you would only have 1.85 volts left from the original 5 volts you started with if you use 40,000 uF. =20 Lets assume that the regulator has a drop out voltage of say 0.2 volts. What this means is that the regulator input must never drop below 3.5 volts in order to maintain the 3.3 volts on the regulator output. This means that the time allowed to switch between power sources would be limited by the time it takes the voltage to drop from 5 volts to 3.5 volts. =20 Vreg + 0.2Vdropout =3D 5 volts * e^(-t/RC) 3.5v/5v =3D e^(-t/RC) ln(3.5/5) =3D -t/RC C =3D (-t/R)/ln(0.7) I did a quick calculation and I come up with C =3D t/(0.35667 * R). I think the capacitor would actually have to be about 112,000 uF for the example you give. Mind you if the change-over took more than a second then the 3.3 volt would no longer be in regulation and who knows what would be taking place in the cpu. I could be wrong but I don't think the gumstix is drawing anywhere near 200 ma. That would be a 1 watt power dissipation at 5 volts. I believe that this would cause the entire waysmall to warm up a little bit when it is in use. I can not feel any temperature rise in the case when it is running. Now I haven't put my finger on the cpu when it is running but I don't think it is getting very warm. Someone monitoring the list probably knows exactly how much current the gumstix draws with some basic I/O connections lke USB or RS232. Anyone have an actual number? -----Original Message----- From: Dave Hylands [mailto:dhylands@...]=20 Sent: Wednesday, January 19, 2005 9:13 AM To: gumstix-users@... Subject: Re: [Gumstix-users] power plug dimensions? Hi Arthur, On Wed, 19 Jan 2005 16:39:41 +0000, Arthur Magill wrote: > > > > The jack on the board has a built-in switch, and I wired up my=20 > > battery connector to take advantage of it. This causes the battery=20 > > to be disconnected with the power jack is plugged in. > > >=20 > Dave, >=20 > Can you 'hot swap' the power, or does that make the gumstix reset? I=20 > guess there must be a solution, using a capacitor to bridge the power=20 > while the switch flips? That's a very good question. I'll have to try it when I get home tonight. Using a capacitor would probably work. I did a quick calculation (maybe somebody else can check this since analog electronics isn't my strong suit). If we assume that the gumstix draws 200 ma at 5v, then we get an effective resistance of 25 ohms. t =3D RC, so C =3D t/R. If we set t to = be 1 second, then we need C =3D 1/25 =3D 0.04 F (or 40,000 uF). I know you can some small supercaps, like this one: http://www.solarbotics.com/products/index.php?scdfa-250100084-viewDetail -productzq3808zq4categoryzq34=3Dtrue I have one these at home - I'll have to see if it fits in the case. -- Dave Hylands Vancouver, BC, Canada http://www.DaveHylands.com/ ------------------------------------------------------- The SF.Net email is sponsored by: Beat the post-holiday blues Get a FREE limited edition SourceForge.net t-shirt from ThinkGeek. It's fun and FREE -- well, almost....http://www.thinkgeek.com/sfshirt _______________________________________________ gumstix-users mailing list gumstix-users@... https://lists.sourceforge.net/lists/listinfo/gumstix-users ```
 Re: [Gumstix-users] power plug dimensions? From: Eric Heinemann - 2005-01-19 06:11:51 ```I found a plug that fits the power jack at Radio Shack. I can attempt to find the package again for the UPC and part number if you like. You will have to solder it to the cables of the battery holder though. Let me know and I'll dig around for it. Eric --- Chris Radcliff wrote: > Gordon Kruberg wrote: > > Sorry, I will really try to get more info like this posted! > > http://www.gumstix.org/tikiwiki/tiki-index.php?page=POWER_JACK > > Understood. It's not like you have anything else to do. ;) > > Thanks! The link led me to a document with the dimensions of the power > jack. (Dave's dimensions were very close, 0.65mm for the pin.) > Unfortunately, DigiKey doesn't carry it any longer and doesn't list a > corresponding power plug (female end), which is what I need to figure > out. I'll keep looking. > > Dave Hylands wrote: > > I've powerd my gumstix/waysmall using 3 AA-NiMH batteries. I krazy > > glued a connector on my waysmall board and soldered it to the back of > > the normal power jack. > > Thanks for the suggestion. Is that preferable to using the existing > jack? I was envisioning something like: > > power jack <= power plug header <===cable=== battery holder > > ...which hopefully would get around the need to solder anything to the > board. I'm a soldering novice, so I'd prefer to make my mistakes on > the power plug. ;) > > Thanks again, > ~chris > > > > ------------------------------------------------------- > The SF.Net email is sponsored by: Beat the post-holiday blues > Get a FREE limited edition SourceForge.net t-shirt from ThinkGeek. > It's fun and FREE -- well, almost....http://www.thinkgeek.com/sfshirt > _______________________________________________ > gumstix-users mailing list > gumstix-users@... > https://lists.sourceforge.net/lists/listinfo/gumstix-users > __________________________________ Do you Yahoo!? Meet the all-new My Yahoo! - Try it today! http://my.yahoo.com ```
 Re: [Gumstix-users] power plug dimensions? From: Dave Hylands - 2005-01-19 06:31:05 ```Hi Chris, On Tue, 18 Jan 2005 20:50:18 -0800, Chris Radcliff wrote: > Gordon Kruberg wrote: > > Sorry, I will really try to get more info like this posted! > > http://www.gumstix.org/tikiwiki/tiki-index.php?page=POWER_JACK > > Understood. It's not like you have anything else to do. ;) > > Thanks! The link led me to a document with the dimensions of the power > jack. (Dave's dimensions were very close, 0.65mm for the pin.) > Unfortunately, DigiKey doesn't carry it any longer and doesn't list a > corresponding power plug (female end), which is what I need to figure > out. I'll keep looking. I updated the page with the part #'s on it. Gordon provided the critical clue. I updated it to read like this: The power jack is from CUI Inc., Part Number PJ1-022-SMT and can be purchased at Digikey, Part Number CP-022PJTR-ND (tape reel - min qty 1000) or CP1-022PJCT-ND (cut tape - min qty 1). There is also a through-hole verision CUI part: PJ1-022, Digikey part number CP1-022-ND The mating plug (which would be at the end of the power adapter cord) is available as CUI Part number PP-012, Digikey part number CP-012-ND. > Dave Hylands wrote: > > I've powerd my gumstix/waysmall using 3 AA-NiMH batteries. I krazy > > glued a connector on my waysmall board and soldered it to the back of > > the normal power jack. > > Thanks for the suggestion. Is that preferable to using the existing > jack? I was envisioning something like: > > power jack <= power plug header <===cable=== battery holder > > ...which hopefully would get around the need to solder anything to the > board. I'm a soldering novice, so I'd prefer to make my mistakes on > the power plug. ;) If you're squemish about soldering to the waysmall board, then by all means just wire up a plug to your battery pack. IMPORTANT: make sure you get the POLARITY right!!!!! The solder pads on the power jack are pretty big (relatively speaking). I figured if I screwed up, I can always buy another waysmall board (they're only \$20). The jack on the board has a built-in switch, and I wired up my battery connector to take advantage of it. This causes the battery to be disconnected with the power jack is plugged in. You can see a picture of my mod here: http://www.davehylands.com/linux/gumstix/Case-Fit/HPNX0079.html In my photo, red is +ve (the center pin) and black is ground (the outer shell). -- Dave Hylands Vancouver, BC, Canada http://www.DaveHylands.com/ ```
 Re: [Gumstix-users] power plug dimensions? From: Arthur Magill - 2005-01-19 16:38:14 ```> > The jack on the board has a built-in switch, and I wired up my battery > connector to take advantage of it. This causes the battery to be > disconnected with the power jack is plugged in. > Dave, Can you 'hot swap' the power, or does that make the gumstix reset? I guess there must be a solution, using a capacitor to bridge the power while the switch flips? Arthur This message has been checked for viruses but the contents of an attachment may still contain software viruses, which could damage your computer system: you are advised to perform your own checks. Email communications with the University of Nottingham may be monitored as permitted by UK legislation. ```
 Re: [Gumstix-users] power plug dimensions? From: Dave Hylands - 2005-01-19 17:12:51 ```Hi Arthur, On Wed, 19 Jan 2005 16:39:41 +0000, Arthur Magill wrote: > > > > The jack on the board has a built-in switch, and I wired up my battery > > connector to take advantage of it. This causes the battery to be > > disconnected with the power jack is plugged in. > > > > Dave, > > Can you 'hot swap' the power, or does that make the gumstix reset? I > guess there must be a solution, using a capacitor to bridge the power > while the switch flips? That's a very good question. I'll have to try it when I get home tonight. Using a capacitor would probably work. I did a quick calculation (maybe somebody else can check this since analog electronics isn't my strong suit). If we assume that the gumstix draws 200 ma at 5v, then we get an effective resistance of 25 ohms. t = RC, so C = t/R. If we set t to be 1 second, then we need C = 1/25 = 0.04 F (or 40,000 uF). I know you can some small supercaps, like this one: http://www.solarbotics.com/products/index.php?scdfa-250100084-viewDetail-productzq3808zq4categoryzq34=true I have one these at home - I'll have to see if it fits in the case. -- Dave Hylands Vancouver, BC, Canada http://www.DaveHylands.com/ ```
 Re: [Gumstix-users] power plug dimensions? From: Arthur Magill - 2005-01-19 19:34:32 ```Hi Dave, Yep, your analysis gives the right numbers. That's a monster cap! I'm not sure how long to allow the switch to flip, but it should be much shorter than a second. 1ms? Maybe using the mechanical switch to flip a FET switch would be faster/more predictable. Of course, it's worth doing this before the voltage regulator, to help keep the gumstix supply as clean as possible. I guess the difficult bit is preventing glitches on the power supply. Interesting idea... Arthur This message has been checked for viruses but the contents of an attachment may still contain software viruses, which could damage your computer system: you are advised to perform your own checks. Email communications with the University of Nottingham may be monitored as permitted by UK legislation. ```
 Re: [Gumstix-users] power plug dimensions? From: Dave Hylands - 2005-01-20 07:35:33 ```Hi Arthur, > > Can you 'hot swap' the power, or does that make the gumstix reset? I > > guess there must be a solution, using a capacitor to bridge the power > > while the switch flips? > > That's a very good question. I'll have to try it when I get home > tonight. Using a capacitor would probably work. Hot swapping causes the gumstix to reset. I couldn't find my 0.047F caps, but it still resets with a 6800 uF (the largest cap I could find in my box) -- Dave Hylands Vancouver, BC, Canada http://www.DaveHylands.com/ ```