Inline power supply (was: Re: Longer XO transformer power cord in the plans?)
On Sun, May 31, 2009 at 12:23:37AM -0400, John Watlington wrote: We are considering changing from a wall wart design to an inline design, for the following reasons: [...] What got of this idea? The XO-1.5s that just arrived included a wall wart again - a bit larger than the XO-1 one, so I had to completely cut off the US - CEE 7/4 plug adapter, making it unsafe to use as it's possible for a child to touch the live contacts when the power supply is plugged in about half-way. :-/ (Yes, I do realise this is probably about the same level of safety most US children are exposed to). CU Sascha -- http://sascha.silbe.org/ http://www.infra-silbe.de/ signature.asc Description: Digital signature ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: Inline power supply (was: Re: Longer XO transformer power cord in the plans?)
The inline adapter is still slated for production, but due to supplier issues didn't ship with the ramp units. Instead, the ramp units (and some early production) will ship with a stock white wall-mount unit. Would you rather that I held up your test unit while we waited for the supplier to provide them ? wad On Mar 16, 2010, at 9:49 AM, Sascha Silbe wrote: On Sun, May 31, 2009 at 12:23:37AM -0400, John Watlington wrote: We are considering changing from a wall wart design to an inline design, for the following reasons: [...] What got of this idea? The XO-1.5s that just arrived included a wall wart again - a bit larger than the XO-1 one, so I had to completely cut off the US - CEE 7/4 plug adapter, making it unsafe to use as it's possible for a child to touch the live contacts when the power supply is plugged in about half-way. :-/ (Yes, I do realise this is probably about the same level of safety most US children are exposed to). CU Sascha -- http://sascha.silbe.org/ http://www.infra-silbe.de/ ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: Inline power supply (was: Re: Longer XO transformer power cord in the plans?)
On Tue, Mar 16, 2010 at 12:13:43PM -0400, John Watlington wrote: The inline adapter is still slated for production, but due to supplier issues didn't ship with the ramp units. Thanks, that's good news! Would you rather that I held up your test unit while we waited for the supplier to provide them ? Seems like my message could be interpreted as some kind of complaint. It wasn't my intention, but re-reading it myself I can see why you took it that way. I apologize for that. I'm aware I got a developer unit (and am quite grateful for that!), not a production one which would most likely be shipped with a plug matching the local sockets. I was mostly worried that others might face the same plug compatibility problems and not be careful enough, especially after having read reports about XO-1 wall warts being repaired in ways that gave me the creeps. CU Sascha -- http://sascha.silbe.org/ http://www.infra-silbe.de/ signature.asc Description: Digital signature ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: Longer XO transformer power cord in the plans?
On 31 May 2009, at 15:34, Reinder de Haan wrote: Tiago Marques wrote: On 5/31/09, Reinder de Haan r...@mveas.com wrote: Sascha Silbe wrote: On Sun, May 31, 2009 at 03:16:53PM +1000, James Cameron wrote: 1. Earthing. The current design has no earth at the AC end, and is isolated in relation to the DC end. An earthed AC plug in some countries produces a more reliable and positive insertion and anchoring. All travel adapters (power outlet adapters) I've come across so far had no earthing so would be impossible to use (unaltered). Of course this wouldn't be much of a change as the current wall warts also don't fit any adapter I've seen at shops. At SugarCamp in Paris, quite a few people (including myself) had custom ones, i.e. with mechanic alterations. Personally, I feel comfortable making minor mechanic changes to an adapter, but I won't usually dare using a non-earthing adapter with a device having an earthed plug (unless I know for sure this is safe). Actually, if you are able to use a standard plug (e.g. IEC-60320- C5/C6) at the power supply end, above won't apply at all as it's usually easy to get a matching cable, no travel adapter needed. :) +1 for inline adaptor its MUCH easier to exchange only the mains cable: 1) when its demaged 2) when shiping to a different part of the world you would need only one powersupply brick for (almost?) all or the world. i have seen some companies ship a couple of different cables so the device is usable almost everywhere and doesn't need to be custom packed/country. i would go which IEC-60320 C8/C9 which is used for half of the laptops today. Completely not the picture around this part of Europe. Most of them come with C13 and some are being sold with C7, which is pretty much a oops i meant C7/C8 NOT C9!! This map appeared in my feeds today, a nice illustration of world usage (don't know how accurate it is, but seems good from what I know of): http://www.eurocom.com/support/images/plug_map.jpg Regards, --Gary standard for other types electronics. C13 would be my favorite, if the size of the plug is not an issue, since it is also the standard for computer power supplies. As mentioned above, C5 would also be sweet. both are an earthed connector and so 'require' an earthed outlet. combined with that almost all power supplies i have seen with a C5/ C6 or C13/C14 connect the earth input to the ground/0V dc output... if you insert such power supply into an not earthed outlet (which are quite common) your whole laptop will be at ~1/2*Uin Vac due to the filter capacitors in the mains filter. which gives a nasty shock if you touch both a non insulated part of your laptop and a earthed object.. As for safety, adding something like the cable plug of the original Xbox pads would work perfectly and it's not as expensive as Apple's magnetic plug. Cost of this is something I have no clue about. Best regards, Tiago Marques i feel a earthed design only increases the risks, even more so when you cant depend on the quality of the mains supply. the only advantage to the earthed design that im aware of is that the power supply easier(cheaper?) meets EMC/FCC regulations. I hope future XO versions will still have the same broad power input specs as the XO-1. It's been very useful already (e.g. cable-only car adapter, no voltage conversion or even voltage limit necessary). CU Sascha ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: Longer XO transformer power cord in the plans?
The chart is of limited utility. For example, Argentina and Oz share the same socket except that the pins are different lengths, so that if you try to import an Oz plug into Argentina, you will get stopped in customs. (Lesson learned the hard way.) -walter On Mon, Jun 1, 2009 at 12:06 PM, Gary C Martin g...@garycmartin.com wrote: On 31 May 2009, at 15:34, Reinder de Haan wrote: Tiago Marques wrote: On 5/31/09, Reinder de Haan r...@mveas.com wrote: Sascha Silbe wrote: On Sun, May 31, 2009 at 03:16:53PM +1000, James Cameron wrote: 1. Earthing. The current design has no earth at the AC end, and is isolated in relation to the DC end. An earthed AC plug in some countries produces a more reliable and positive insertion and anchoring. All travel adapters (power outlet adapters) I've come across so far had no earthing so would be impossible to use (unaltered). Of course this wouldn't be much of a change as the current wall warts also don't fit any adapter I've seen at shops. At SugarCamp in Paris, quite a few people (including myself) had custom ones, i.e. with mechanic alterations. Personally, I feel comfortable making minor mechanic changes to an adapter, but I won't usually dare using a non-earthing adapter with a device having an earthed plug (unless I know for sure this is safe). Actually, if you are able to use a standard plug (e.g. IEC-60320- C5/C6) at the power supply end, above won't apply at all as it's usually easy to get a matching cable, no travel adapter needed. :) +1 for inline adaptor its MUCH easier to exchange only the mains cable: 1) when its demaged 2) when shiping to a different part of the world you would need only one powersupply brick for (almost?) all or the world. i have seen some companies ship a couple of different cables so the device is usable almost everywhere and doesn't need to be custom packed/country. i would go which IEC-60320 C8/C9 which is used for half of the laptops today. Completely not the picture around this part of Europe. Most of them come with C13 and some are being sold with C7, which is pretty much a oops i meant C7/C8 NOT C9!! This map appeared in my feeds today, a nice illustration of world usage (don't know how accurate it is, but seems good from what I know of): http://www.eurocom.com/support/images/plug_map.jpg Regards, --Gary standard for other types electronics. C13 would be my favorite, if the size of the plug is not an issue, since it is also the standard for computer power supplies. As mentioned above, C5 would also be sweet. both are an earthed connector and so 'require' an earthed outlet. combined with that almost all power supplies i have seen with a C5/ C6 or C13/C14 connect the earth input to the ground/0V dc output... if you insert such power supply into an not earthed outlet (which are quite common) your whole laptop will be at ~1/2*Uin Vac due to the filter capacitors in the mains filter. which gives a nasty shock if you touch both a non insulated part of your laptop and a earthed object.. As for safety, adding something like the cable plug of the original Xbox pads would work perfectly and it's not as expensive as Apple's magnetic plug. Cost of this is something I have no clue about. Best regards, Tiago Marques i feel a earthed design only increases the risks, even more so when you cant depend on the quality of the mains supply. the only advantage to the earthed design that im aware of is that the power supply easier(cheaper?) meets EMC/FCC regulations. I hope future XO versions will still have the same broad power input specs as the XO-1. It's been very useful already (e.g. cable-only car adapter, no voltage conversion or even voltage limit necessary). CU Sascha ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel -- Walter Bender Sugar Labs http://www.sugarlabs.org ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: Longer XO transformer power cord in the plans?
On Sun, May 31, 2009 at 03:16:53PM +1000, James Cameron wrote: 1. Earthing. The current design has no earth at the AC end, and is isolated in relation to the DC end. An earthed AC plug in some countries produces a more reliable and positive insertion and anchoring. All travel adapters (power outlet adapters) I've come across so far had no earthing so would be impossible to use (unaltered). Of course this wouldn't be much of a change as the current wall warts also don't fit any adapter I've seen at shops. At SugarCamp in Paris, quite a few people (including myself) had custom ones, i.e. with mechanic alterations. Personally, I feel comfortable making minor mechanic changes to an adapter, but I won't usually dare using a non-earthing adapter with a device having an earthed plug (unless I know for sure this is safe). Actually, if you are able to use a standard plug (e.g. IEC-60320-C5/C6) at the power supply end, above won't apply at all as it's usually easy to get a matching cable, no travel adapter needed. :) I hope future XO versions will still have the same broad power input specs as the XO-1. It's been very useful already (e.g. cable-only car adapter, no voltage conversion or even voltage limit necessary). CU Sascha -- http://sascha.silbe.org/ http://www.infra-silbe.de/ signature.asc Description: Digital signature ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: Longer XO transformer power cord in the plans?
Sascha Silbe wrote: On Sun, May 31, 2009 at 03:16:53PM +1000, James Cameron wrote: 1. Earthing. The current design has no earth at the AC end, and is isolated in relation to the DC end. An earthed AC plug in some countries produces a more reliable and positive insertion and anchoring. All travel adapters (power outlet adapters) I've come across so far had no earthing so would be impossible to use (unaltered). Of course this wouldn't be much of a change as the current wall warts also don't fit any adapter I've seen at shops. At SugarCamp in Paris, quite a few people (including myself) had custom ones, i.e. with mechanic alterations. Personally, I feel comfortable making minor mechanic changes to an adapter, but I won't usually dare using a non-earthing adapter with a device having an earthed plug (unless I know for sure this is safe). Actually, if you are able to use a standard plug (e.g. IEC-60320-C5/C6) at the power supply end, above won't apply at all as it's usually easy to get a matching cable, no travel adapter needed. :) +1 for inline adaptor its MUCH easier to exchange only the mains cable: 1) when its demaged 2) when shiping to a different part of the world you would need only one powersupply brick for (almost?) all or the world. i have seen some companies ship a couple of different cables so the device is usable almost everywhere and doesn't need to be custom packed/country. i would go which IEC-60320 C8/C9 which is used for half of the laptops today. i feel a earthed design only increases the risks, even more so when you cant depend on the quality of the mains supply. the only advantage to the earthed design that im aware of is that the power supply easier(cheaper?) meets EMC/FCC regulations. I hope future XO versions will still have the same broad power input specs as the XO-1. It's been very useful already (e.g. cable-only car adapter, no voltage conversion or even voltage limit necessary). CU Sascha ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: Longer XO transformer power cord in the plans?
On 31.05.2009, at 06:23, John Watlington wrote: I am still getting quotes to see how this change might impact the adapter cost, and getting the industrial designers to think about it. Are you having them think of daisy-chaining, too? Like older PCs having both a C14 power inlet and a C13 outlet ... - Bert - ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: Longer XO transformer power cord in the plans?
On 5/31/09, James Cameron qu...@laptop.org wrote: I know of no such plans, but the physics of the configuration has a bearing ... 1. a longer cable has a larger voltage drop, and so a greater amount of power is lost as heat, leading to greater inefficiency of power use, 2. compensating for the voltage drop can only be done by either raising the design voltage on the cable, or increasing the cross sectional area of the copper, 3. raising the design voltage is an unattractive option, since it would expose the user to greater risk, 4. increasing the cross sectional area would make the cable much heavier, and a substantially higher cost, which would vary according to metal prices, 5. increasing the length may also increase the trip hazard, and so further reinforcement of the sheath and restraint points may be required, 6. not every child will need an extra two metres. I have no idea of the kind of infrastructures kids have on the target market of the project, at least in developed countries it is a necessity for me, hence the e-mail I sent. Can you balance this against against the cost of properly placed domestic 110V or 240V outlets? Nope, I understand that. Best regards, Tiago Marques -- James Cameronmailto:qu...@us.netrek.org http://quozl.netrek.org/ ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: Longer XO transformer power cord in the plans?
On 5/31/09, Reinder de Haan r...@mveas.com wrote: Sascha Silbe wrote: On Sun, May 31, 2009 at 03:16:53PM +1000, James Cameron wrote: 1. Earthing. The current design has no earth at the AC end, and is isolated in relation to the DC end. An earthed AC plug in some countries produces a more reliable and positive insertion and anchoring. All travel adapters (power outlet adapters) I've come across so far had no earthing so would be impossible to use (unaltered). Of course this wouldn't be much of a change as the current wall warts also don't fit any adapter I've seen at shops. At SugarCamp in Paris, quite a few people (including myself) had custom ones, i.e. with mechanic alterations. Personally, I feel comfortable making minor mechanic changes to an adapter, but I won't usually dare using a non-earthing adapter with a device having an earthed plug (unless I know for sure this is safe). Actually, if you are able to use a standard plug (e.g. IEC-60320-C5/C6) at the power supply end, above won't apply at all as it's usually easy to get a matching cable, no travel adapter needed. :) +1 for inline adaptor its MUCH easier to exchange only the mains cable: 1) when its demaged 2) when shiping to a different part of the world you would need only one powersupply brick for (almost?) all or the world. i have seen some companies ship a couple of different cables so the device is usable almost everywhere and doesn't need to be custom packed/country. i would go which IEC-60320 C8/C9 which is used for half of the laptops today. Completely not the picture around this part of Europe. Most of them come with C13 and some are being sold with C7, which is pretty much a standard for other types electronics. C13 would be my favorite, if the size of the plug is not an issue, since it is also the standard for computer power supplies. As mentioned above, C5 would also be sweet. As for safety, adding something like the cable plug of the original Xbox pads would work perfectly and it's not as expensive as Apple's magnetic plug. Cost of this is something I have no clue about. Best regards, Tiago Marques i feel a earthed design only increases the risks, even more so when you cant depend on the quality of the mains supply. the only advantage to the earthed design that im aware of is that the power supply easier(cheaper?) meets EMC/FCC regulations. I hope future XO versions will still have the same broad power input specs as the XO-1. It's been very useful already (e.g. cable-only car adapter, no voltage conversion or even voltage limit necessary). CU Sascha ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: Longer XO transformer power cord in the plans?
Tiago Marques wrote: On 5/31/09, Reinder de Haan r...@mveas.com wrote: Sascha Silbe wrote: On Sun, May 31, 2009 at 03:16:53PM +1000, James Cameron wrote: 1. Earthing. The current design has no earth at the AC end, and is isolated in relation to the DC end. An earthed AC plug in some countries produces a more reliable and positive insertion and anchoring. All travel adapters (power outlet adapters) I've come across so far had no earthing so would be impossible to use (unaltered). Of course this wouldn't be much of a change as the current wall warts also don't fit any adapter I've seen at shops. At SugarCamp in Paris, quite a few people (including myself) had custom ones, i.e. with mechanic alterations. Personally, I feel comfortable making minor mechanic changes to an adapter, but I won't usually dare using a non-earthing adapter with a device having an earthed plug (unless I know for sure this is safe). Actually, if you are able to use a standard plug (e.g. IEC-60320-C5/C6) at the power supply end, above won't apply at all as it's usually easy to get a matching cable, no travel adapter needed. :) +1 for inline adaptor its MUCH easier to exchange only the mains cable: 1) when its demaged 2) when shiping to a different part of the world you would need only one powersupply brick for (almost?) all or the world. i have seen some companies ship a couple of different cables so the device is usable almost everywhere and doesn't need to be custom packed/country. i would go which IEC-60320 C8/C9 which is used for half of the laptops today. Completely not the picture around this part of Europe. Most of them come with C13 and some are being sold with C7, which is pretty much a oops i meant C7/C8 NOT C9!! standard for other types electronics. C13 would be my favorite, if the size of the plug is not an issue, since it is also the standard for computer power supplies. As mentioned above, C5 would also be sweet. both are an earthed connector and so 'require' an earthed outlet. combined with that almost all power supplies i have seen with a C5/C6 or C13/C14 connect the earth input to the ground/0V dc output... if you insert such power supply into an not earthed outlet (which are quite common) your whole laptop will be at ~1/2*Uin Vac due to the filter capacitors in the mains filter. which gives a nasty shock if you touch both a non insulated part of your laptop and a earthed object.. As for safety, adding something like the cable plug of the original Xbox pads would work perfectly and it's not as expensive as Apple's magnetic plug. Cost of this is something I have no clue about. Best regards, Tiago Marques i feel a earthed design only increases the risks, even more so when you cant depend on the quality of the mains supply. the only advantage to the earthed design that im aware of is that the power supply easier(cheaper?) meets EMC/FCC regulations. I hope future XO versions will still have the same broad power input specs as the XO-1. It's been very useful already (e.g. cable-only car adapter, no voltage conversion or even voltage limit necessary). CU Sascha ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: Longer XO transformer power cord in the plans?
On Sun, May 31, 2009 at 3:34 PM, Reinder de Haan r...@mveas.com wrote: Tiago Marques wrote: On 5/31/09, Reinder de Haan r...@mveas.com wrote: Sascha Silbe wrote: On Sun, May 31, 2009 at 03:16:53PM +1000, James Cameron wrote: 1. Earthing. The current design has no earth at the AC end, and is isolated in relation to the DC end. An earthed AC plug in some countries produces a more reliable and positive insertion and anchoring. All travel adapters (power outlet adapters) I've come across so far had no earthing so would be impossible to use (unaltered). Of course this wouldn't be much of a change as the current wall warts also don't fit any adapter I've seen at shops. At SugarCamp in Paris, quite a few people (including myself) had custom ones, i.e. with mechanic alterations. Personally, I feel comfortable making minor mechanic changes to an adapter, but I won't usually dare using a non-earthing adapter with a device having an earthed plug (unless I know for sure this is safe). Actually, if you are able to use a standard plug (e.g. IEC-60320-C5/C6) at the power supply end, above won't apply at all as it's usually easy to get a matching cable, no travel adapter needed. :) +1 for inline adaptor its MUCH easier to exchange only the mains cable: 1) when its demaged 2) when shiping to a different part of the world you would need only one powersupply brick for (almost?) all or the world. i have seen some companies ship a couple of different cables so the device is usable almost everywhere and doesn't need to be custom packed/country. i would go which IEC-60320 C8/C9 which is used for half of the laptops today. Completely not the picture around this part of Europe. Most of them come with C13 and some are being sold with C7, which is pretty much a oops i meant C7/C8 NOT C9!! standard for other types electronics. C13 would be my favorite, if the size of the plug is not an issue, since it is also the standard for computer power supplies. As mentioned above, C5 would also be sweet. both are an earthed connector and so 'require' an earthed outlet. combined with that almost all power supplies i have seen with a C5/C6 or C13/C14 connect the earth input to the ground/0V dc output... if you insert such power supply into an not earthed outlet (which are quite common) your whole laptop will be at ~1/2*Uin Vac due to the filter capacitors in the mains filter. which gives a nasty shock if you touch both a non insulated part of your laptop and a earthed object.. Sadly true, but a redisign of the XO power supply wouldn't take the earthing into account, right? So no problems for us. The power adapter can be design like with the C17 instead, which will also accept the more abundant C13 cables. The unpolarised C7 is also quite common and smaller, could be a better choice, IMHO, than any of the C13 or C5. Best regards, Tiago Marques As for safety, adding something like the cable plug of the original Xbox pads would work perfectly and it's not as expensive as Apple's magnetic plug. Cost of this is something I have no clue about. Best regards, Tiago Marques i feel a earthed design only increases the risks, even more so when you cant depend on the quality of the mains supply. the only advantage to the earthed design that im aware of is that the power supply easier(cheaper?) meets EMC/FCC regulations. I hope future XO versions will still have the same broad power input specs as the XO-1. It's been very useful already (e.g. cable-only car adapter, no voltage conversion or even voltage limit necessary). CU Sascha ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Longer XO transformer power cord in the plans?
Hi all, Does anyone have plans to give 2 extra meters on the power cord of the XO-1 transformer, maybe in time for Gen 1.5? I don't have a clue of the usage scenario on underdeveloped countries but it sure would come in very useful to have some extra length on this power cord. At least I feel severe limitations with something as short as we have now. Best regards, Tiago Marques ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: Longer XO transformer power cord in the plans?
I know of no such plans, but the physics of the configuration has a bearing ... 1. a longer cable has a larger voltage drop, and so a greater amount of power is lost as heat, leading to greater inefficiency of power use, 2. compensating for the voltage drop can only be done by either raising the design voltage on the cable, or increasing the cross sectional area of the copper, 3. raising the design voltage is an unattractive option, since it would expose the user to greater risk, 4. increasing the cross sectional area would make the cable much heavier, and a substantially higher cost, which would vary according to metal prices, 5. increasing the length may also increase the trip hazard, and so further reinforcement of the sheath and restraint points may be required, 6. not every child will need an extra two metres. Can you balance this against against the cost of properly placed domestic 110V or 240V outlets? -- James Cameronmailto:qu...@us.netrek.org http://quozl.netrek.org/ ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: Longer XO transformer power cord in the plans?
We are considering changing from a wall wart design to an inline design, for the following reasons: A - The difficulty in supporting new countries, when each new plug design requires new tooling. With an inline design, only the plug at the end of the AC cable has to change. B - The wall wart design limits the weight of the adapter. C - A blow to the adapter when it is plugged in frequently snaps the pins off of the wall wart. I've seen a number of repaired units that make me worry for the kids safety. D - It can be difficult to find power strips with the right plug orientation to accept multiple adapters of our current design. Right now, we have a 1.5m cable on the wall wart. I'm thnking about specifying a 0.8m (outlet to floor) AC cable and a 1.2m (floor to table) DC cable. Shorter would be cheaper, but might result in dangling adapters, something to be avoided. Quozl's comments are valid. Not every child needs a longer cable, and the cabling is a significant part of the cost of the adapter. I am still getting quotes to see how this change might impact the adapter cost, and getting the industrial designers to think about it. Comments ? Suggestions ? wad On May 30, 2009, at 9:39 PM, James Cameron wrote: I know of no such plans, but the physics of the configuration has a bearing ... 1. a longer cable has a larger voltage drop, and so a greater amount of power is lost as heat, leading to greater inefficiency of power use, 2. compensating for the voltage drop can only be done by either raising the design voltage on the cable, or increasing the cross sectional area of the copper, 3. raising the design voltage is an unattractive option, since it would expose the user to greater risk, 4. increasing the cross sectional area would make the cable much heavier, and a substantially higher cost, which would vary according to metal prices, 5. increasing the length may also increase the trip hazard, and so further reinforcement of the sheath and restraint points may be required, 6. not every child will need an extra two metres. Can you balance this against against the cost of properly placed domestic 110V or 240V outlets? -- James Cameronmailto:qu...@us.netrek.org http:// quozl.netrek.org/ ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: Longer XO transformer power cord in the plans?
On Sun, May 31, 2009 at 12:23:37AM -0400, John Watlington wrote: Comments ? Suggestions ? Everything you said seems good to me, and I agree. A few things to add to your list: 1. Earthing. The current design has no earth at the AC end, and is isolated in relation to the DC end. An earthed AC plug in some countries produces a more reliable and positive insertion and anchoring. I don't know what the standards are for the isolation, but I've detected both isolated and earth pass-through designs on other systems. 2. Indicator. With a larger unit a small LED power indication may be helpful. 3. Inrush. Some of the adapters on other product I've used have a significant inrush current during the time of a typical AC power switch bounce. This results in momentary arcing, either on insertion into a live socket or on switch-on. One finds arc cavitation on the initial contact point. I've just inspected the adapters here; the B1/B2 series have negligible cavitation, the C2 series have easily detected cavitation. One can hear the arc on insertion of the C2 series adapter into a 240V socket. -- James Cameronmailto:qu...@us.netrek.org http://quozl.netrek.org/ ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
