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#1
Posted to alt.home.repair,sci.electonics.repair
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Why 3-prong plugs
Why do laptop power supplies, the ones with black rectangular things in
the middle of the cord, have 3-prong plugs when everything you can touch is plastic or "rubber"? And, I believe, when there's nothing more dangerous than a lamp underneath the plastic and the rubber? Less dangerous because some light bulbs ger really hot! |
#2
Posted to alt.home.repair,sci.electonics.repair
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Why 3-prong plugs
On 3/7/17 4:29 PM, micky wrote:
Why do laptop power supplies, the ones with black rectangular things in the middle of the cord, have 3-prong plugs when everything you can touch is plastic or "rubber"? And, I believe, when there's nothing more dangerous than a lamp underneath the plastic and the rubber? Less dangerous because some light bulbs ger really hot! I have a Toshiba Netbook with a small "black rectangular thing" that is only 2-prong. The Mac Mini has a large white thing that is 2 prong. |
#3
Posted to alt.home.repair,sci.electonics.repair
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Why 3-prong plugs
On Tue, 07 Mar 2017 16:29:46 -0500, micky
wrote: Why do laptop power supplies, the ones with black rectangular things in the middle of the cord, have 3-prong plugs when everything you can touch is plastic or "rubber"? And, I believe, when there's nothing more dangerous than a lamp underneath the plastic and the rubber? Less dangerous because some light bulbs ger really hot! If the power supply were to short power could get through the laptop, and out the USB or headphone, or whatever jacks.? Anyway, some require grounding by code, others don'r. |
#4
Posted to alt.home.repair
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Why 3-prong plugs
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#5
Posted to alt.home.repair
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Why 3-prong plugs
On Tuesday, March 7, 2017 at 7:27:13 PM UTC-6, wrote:
On Tue, 07 Mar 2017 16:29:46 -0500, micky wrote: Why do laptop power supplies, the ones with black rectangular things in the middle of the cord, have 3-prong plugs when everything you can touch is plastic or "rubber"? And, I believe, when there's nothing more dangerous than a lamp underneath the plastic and the rubber? Less dangerous because some light bulbs ger really hot! If the power supply were to short power could get through the laptop, and out the USB or headphone, or whatever jacks.? Anyway, some require grounding by code, others don'r. Many manufacturers put an IEC socket on the laptop power supplies because the power supplies will operate on multiple voltages. It's simple to change the cord that's shipped with the laptop depending on the area of the world it's sold in. It's the same with desktop computers. If the computer is shipped to a part of the world that uses 220vac 50hz, all you do is use a power cord that has the appropriate plug. t(ツ)_/¯ [8~{} Uncle Power Monster |
#6
Posted to alt.home.repair
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Why 3-prong plugs
micky wrote:
Why do laptop power supplies, the ones with black rectangular things in the middle of the cord, have 3-prong plugs when everything you can touch is plastic or "rubber"? And, I believe, when there's nothing more dangerous than a lamp underneath the plastic and the rubber? Less dangerous because some light bulbs ger really hot! The ac can use ground as part of a filter, capacitor to ground. I have seen ground fed to common on laptop, sometimes causes ground loop problems. Greg |
#7
Posted to alt.home.repair
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Why 3-prong plugs
Why do laptop power supplies, the ones with black rectangular things in the middle of the cord, have 3-prong plugs when everything you can touch is plastic or "rubber"? And, I believe, when there's nothing more dangerous than a lamp underneath the plastic and the rubber? If the power supply were to short power could get through the laptop, and out the USB or headphone, or whatever jacks.? Anyway, some require grounding by code, others don'r. Many manufacturers put an IEC socket on the laptop power supplies because the power supplies will operate on multiple voltages. It's simple to change the cord that's shipped with the laptop depending on the area of the world it's sold in. It's the same with desktop computers. If the computer is shipped to a part of the world that uses 220vac 50hz, all you do is use a power cord that has the appropriate plug. t(?)_/¯ [8~{} Uncle Power Monster My Lenovo laptop has a 2-prong plug and the converter is rated for 240 volts. I guess I am in mortal danger - if "the power supply were to short" ... :-) John T. |
#8
Posted to alt.home.repair,alt.usenet.kooks,alt.war.vietnam
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MICKY ASKS: "Why 3-prong plugs?"
On 3/7/2017 1:29 PM, micky wrote:
Why do laptop power supplies, the ones with black rectangular things in the middle of the cord, have 3-prong plugs when everything you can touch is plastic or "rubber"? Micky, I'm gonna field this one out to the expurts in Cyberland. Take it away, Cyberland dudes........... |
#9
Posted to alt.home.repair,alt.usenet.kooks,alt.war.vietnam
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MICKY ASKS: "Why 3-prong plugs?"
Colonel Edmund J. Burke wrote:
On 3/7/2017 1:29 PM, micky wrote: Why do laptop power supplies, the ones with black rectangular things in the middle of the cord, have 3-prong plugs when everything you can touch is plastic or "rubber"? Micky, I'm gonna field this one out to the expurts in Cyberland. Take it away, Cyberland dudes........... A user might plug in an accessory such as a printer, headphone, flash drive, etc which DOES have exposed metal parts, and the manufacturer wants to have done everything he can to make it safe so he won't be sued...... |
#11
Posted to alt.home.repair
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Why 3-prong plugs
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#12
Posted to alt.home.repair
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Why 3-prong plugs
On Wed, 8 Mar 2017 11:01:06 -0500, Ralph Mowery
wrote: Many computers and some other devices have a switch for 120 or 240 volts and that universal socket on the device. The suplies are really not even that particular about the voltages, just get into the ball park with them. Going 20 or 30 volts either way is fine. These days the switchers are very wide mouth and can take anything from 100-250v at any frequency, even DC although they are not labeled that way. The first thing that happens is the input is converted to DC immediately anyway. Then it is chopped to something in the 10s of thousands of hz, fed through a small toroid transformer, regulated, rectified and comes out at the desired voltage. When went to New Zealand, all I needed was a plug adapter to run every electronic device I had (laptop, phone, camera, MP3 player, tablet etc) All of the chargers were 100-250v. |
#13
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Why 3-prong plugs
On Tuesday, March 7, 2017 at 5:00:39 PM UTC-5, Retired wrote:
On 3/7/17 4:29 PM, micky wrote: Why do laptop power supplies, the ones with black rectangular things in the middle of the cord, have 3-prong plugs when everything you can touch is plastic or "rubber"? And, I believe, when there's nothing more dangerous than a lamp underneath the plastic and the rubber? Less dangerous because some light bulbs ger really hot! I have a Toshiba Netbook with a small "black rectangular thing" that is only 2-prong. The Mac Mini has a large white thing that is 2 prong. Same here with a Dell notebook, it has a two prong power supply. |
#14
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Why 3-prong plugs
On Wed, 8 Mar 2017 11:01:06 -0500, Ralph Mowery
wrote: In article , says... Anyway, some require grounding by code, others don'r. Many manufacturers put an IEC socket on the laptop power supplies because the power supplies will operate on multiple voltages. It's simple to change the cord that's shipped with the laptop depending on the area of the world it's sold in. It's the same with desktop computers. If the computer is shipped to a part of the world that uses 220vac 50hz, all you do is use a power cord that has the appropriate plug. t (?)_/¯ [8~{} Uncle Power Monster They have done that for many years, or in some cases like priners and modems the power supply is seperte so they can just ship seperate supplies depending on the country. Many computers and some other devices have a switch for 120 or 240 volts and that universal socket on the device. The suplies are really not even that particular about the voltages, just get into the ball park with them. Going 20 or 30 volts either way is fine. Power supplies with 120/240 switches are SO 1990. |
#15
Posted to alt.home.repair
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Why 3-prong plugs
On 03/08/2017 08:16 PM, wrote:
[snip] Power supplies with 120/240 switches are SO 1990. WHAT is that supposed to mean? It can't mean that year, since there was nothing special about 1990. Also, I have a PC power supply from last year (2016). It has a 120/240 switch. -- Mark Lloyd http://notstupid.us/ "Think not that I am come to send peace on earth; I came not to send peace, but a sword." [Jesus, Matthew 10:34] |
#16
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Why 3-prong plugs
On Wed, 8 Mar 2017 23:52:14 -0600, Mark Lloyd
wrote: On 03/08/2017 08:16 PM, wrote: [snip] Power supplies with 120/240 switches are SO 1990. WHAT is that supposed to mean? It can't mean that year, since there was nothing special about 1990. Also, I have a PC power supply from last year (2016). It has a 120/240 switch. The design is from 1990. I haven't seen an ATX supply that was not "auto switching" AKA wide mouth and I have a dozen of them in my parts cabinet. |
#17
Posted to alt.home.repair
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Why 3-prong plugs
On Wed, 8 Mar 2017 23:52:14 -0600, Mark Lloyd
wrote: On 03/08/2017 08:16 PM, wrote: [snip] Power supplies with 120/240 switches are SO 1990. SO OLD. Virtually everything in the last20 years anyway is "universal" or "auto switching" in the small SMPS world. Virtually all my laptop powes supplies and switch mode wall warts are listed as 100-240 or the odd one 85-250 volts The odd PC power supply still has a switch (Del and HP up until at least a few years ago) but Acer has been full auto for at least that long. I've got8 nyear old acers that are full automatic, for sure WHAT is that supposed to mean? It can't mean that year, since there was nothing special about 1990. Also, I have a PC power supply from last year (2016). It has a 120/240 switch. |
#18
Posted to alt.home.repair,sci.electonics.repair
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Why 3-prong plugs
micky
Tue, 07 Mar 2017 21:29:46 GMT in alt.home.repair, wrote: Why do laptop power supplies, the ones with black rectangular things in the middle of the cord, have 3-prong plugs when everything you can touch is plastic or "rubber"? Filtering perhaps? Limited surge supression components? Redundant safety...I've got a few laptops around here that have the 3 prong and a couple that don't. I prefer the ones that dont, because, sometimes, the 3 prong ones generate unwanted background hum when fed to external audio amplifiers while plugged into their chargers. -- Sarcasm, because beating the living **** out of deserving people is illegal. |
#19
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Why 3-prong plugs
On Fri, 10 Mar 2017 01:58:15 -0000 (UTC), Diesel
wrote: I prefer the ones that dont, because, sometimes, the 3 prong ones generate unwanted background hum when fed to external audio amplifiers while plugged into their chargers. That implies that the ground is connected to the DC common. Not sure why they would want to do that unless it is just for RF filtering. |
#20
Posted to alt.home.repair
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Why 3-prong plugs
Fri, 10 Mar 2017 07:55:44 GMT in alt.home.repair, wrote:
On Fri, 10 Mar 2017 01:58:15 -0000 (UTC), Diesel wrote: I prefer the ones that dont, because, sometimes, the 3 prong ones generate unwanted background hum when fed to external audio amplifiers while plugged into their chargers. That implies that the ground is connected to the DC common. Not sure why they would want to do that unless it is just for RF filtering. I've suspected the issue is a ground loop based on prior experience with that...I haven't tried to open one of these and take a look inside, so it's entirely possible it is connected, but, due to some filtering circuitry in between, I'm unable to do a simple continuity test on it. By unable, I mean that it doesn't read as completing a circuit when tested in that manner. http://www.channld.com/hum.html This works well to remedy the problem... https://www.amazon.com/Mpow-Ground-I...F6E7CCRCVEDNNN -- Sarcasm, because beating the living **** out of deserving people is illegal. |
#21
Posted to alt.home.repair
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Why 3-prong plugs
On Fri, 10 Mar 2017 10:55:09 -0000 (UTC), Diesel
wrote: Fri, 10 Mar 2017 07:55:44 GMT in alt.home.repair, wrote: On Fri, 10 Mar 2017 01:58:15 -0000 (UTC), Diesel wrote: I prefer the ones that dont, because, sometimes, the 3 prong ones generate unwanted background hum when fed to external audio amplifiers while plugged into their chargers. That implies that the ground is connected to the DC common. Not sure why they would want to do that unless it is just for RF filtering. I've suspected the issue is a ground loop based on prior experience with that...I haven't tried to open one of these and take a look inside, so it's entirely possible it is connected, but, due to some filtering circuitry in between, I'm unable to do a simple continuity test on it. By unable, I mean that it doesn't read as completing a circuit when tested in that manner. http://www.channld.com/hum.html This works well to remedy the problem... https://www.amazon.com/Mpow-Ground-I...F6E7CCRCVEDNNN Reading with a meter you will be looking through the filter so YMMV on what kind of continuity you see but at 60hz there will be some pass through. I have had that problem with desk tops that feed amps, particularly if there are other things in that loop like a TV. |
#22
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Why 3-prong plugs
Fri, 10 Mar 2017 14:55:06 GMT in alt.home.repair, wrote: On Fri, 10 Mar 2017 10:55:09 -0000 (UTC), Diesel wrote: Fri, 10 Mar 2017 07:55:44 GMT in alt.home.repair, wrote: On Fri, 10 Mar 2017 01:58:15 -0000 (UTC), Diesel wrote: I prefer the ones that dont, because, sometimes, the 3 prong ones generate unwanted background hum when fed to external audio amplifiers while plugged into their chargers. That implies that the ground is connected to the DC common. Not sure why they would want to do that unless it is just for RF filtering. I've suspected the issue is a ground loop based on prior experience with that...I haven't tried to open one of these and take a look inside, so it's entirely possible it is connected, but, due to some filtering circuitry in between, I'm unable to do a simple continuity test on it. By unable, I mean that it doesn't read as completing a circuit when tested in that manner. http://www.channld.com/hum.html This works well to remedy the problem... https://www.amazon.com/Mpow-Ground-I...stem/dp/B01939 3MV2/ref=pd_lpo_107_bs_img_2?_encoding=UTF8&psc=1&refRI D=H7D9H4F6E7 CCRCVEDNNN Reading with a meter you will be looking through the filter so YMMV on what kind of continuity you see but at 60hz there will be some pass through. I have had that problem with desk tops that feed amps, particularly if there are other things in that loop like a TV. Same here. When I routed a friends computer thru a mixer board into a stereo system, we had the ground loop hum issue to deal with. Oh the joys of a semi digital recording studio. -- Sarcasm, because beating the living **** out of deserving people is illegal. |
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