It's not just his ego that's insufferable...... On Fri, Feb 25, 2011 at 5:06 PM, William Robbins <[email protected]>wrote:
> Don't encourage -sc...his ego is insufferable as it is. ;) > > - WJR > > > > On Fri, Feb 25, 2011 at 15:51, Jonathan <[email protected]> wrote: > >> +1 SC is dead on here. Match the voltage (and the polarity, if DC), and >> match or exceed the current rating (amps) or the power rating (watts) and >> you'll be fine. Typically (for barrell connectors, anyway, you'll find that >> the size of the connector has to do with the voltage and or amperage of the >> supply. >> >> On a related note, I always appreciate when one of my computer geek >> colleagues quotes Ohm's law. >> >> ....or Kirchhoff's law... >> >> The sum of the currents entering a circuit equal the sum of the currents >> exiting the circuit. >> >> Jonathan >> >> On Fri, Feb 25, 2011 at 1:20 PM, Steven M. Caesare >> <[email protected]>wrote: >> >>> No, Ben is correct here. >>> >>> >>> >>> The resistive load (simplifying, as most modern load have inductive or >>> capacitive components in addition to purely resistive loads), is heat will >>> determine how much he current draw will be. >>> >>> >>> >>> Ohms law tells us I = V/R >>> >>> >>> >>> I-current >>> >>> V=voltage >>> >>> R=resistance >>> >>> >>> >>> Therefore if your supply voltage(V) is 14 volts, and the load >>> resistance(R) is 7 ohms, then the current draw (I) will be 2 amps. >>> >>> >>> >>> Thus your power supply must be capable of supplying at LEAST 2 amps[1], >>> it may be able to supply more, but the system would simply never draw it. A >>> 500A power supply would no more require the load to “dissipate more heat” >>> it than a 2A power supply would. >>> >>> >>> >>> -sc >>> >>> >>> >>> [1] And incidentally, power (W) = V*A. Therefore our theoretical power >>> supply in this case would be supply 28W of power[2]. I not this because >>> power supplies are often capable of varying voltage and/or are rated in >>> watts. >>> >>> [2] Ignoring power efficiency factors for the moment. >>> >>> >>> >>> *From:* Jonathan Link [mailto:[email protected]] >>> *Sent:* Friday, February 25, 2011 1:07 PM >>> >>> *To:* NT System Admin Issues >>> *Subject:* Re: QUICK question... A/C adapters >>> >>> >>> >>> It would depend on whether you can trust the resistor to dissapate the >>> extra heat generated by additional current. It's not something I would do >>> over the long term... >>> >>> >>> >>> >>> >>> On Fri, Feb 25, 2011 at 12:57 PM, Jim Holmgren <[email protected]> >>> wrote: >>> >>> Matt, >>> I believe you are correct. Also not an EE, but in about 10 years of >>> working for RadioShack, that was the mantra. >>> >>> The device will only draw the amperage it needs, but it must have the >>> correct voltage. >>> >>> Jim >>> >>> >>> Jim Holmgren >>> Senior Manager, Infrastructure Services >>> XLHealth Corporation >>> The Warehouse at Camden Yards >>> 351 West Camden Street, Suite 100 >>> Baltimore, MD 21201 >>> 410.625.2200 (main) >>> 443.524.8573 (direct) >>> 443-506.2400 (cell) >>> www.xlhealth.com >>> >>> >>> >>> >>> >>> -----Original Message----- >>> From: Matthew W. Ross [mailto:[email protected]] >>> >>> Sent: Friday, February 25, 2011 12:49 PM >>> To: NT System Admin Issues >>> Subject: RE: QUICK question... A/C adapters >>> >>> I am not an electrical engineer, so please do not take this as power >>> supply advice: >>> >>> I have been told that as long as the voltage is correct, you can go over >>> on the amperage with your PS. So, if you have something that requires >>> 9V, 1 amp PS, and you have a 9 volt, 2 amp... you're good to go. The >>> device will only pull as much amperage as it requires. >>> >>> Voltage is specific, as I'm told. Don't mess with it. AC and DC don't >>> mix, etc, etc... >>> >>> Again, don't use this as any kind of real advice. Somebody with real >>> electrical engineering experience can verify or tell me I've been told >>> wrong. Sm:)e. >>> >>> >>> --Matt Ross >>> Ephrata School District >>> >>> >>> ----- Original Message ----- >>> From: Maglinger, Paul >>> [mailto:[email protected]] >>> To: NT System Admin Issues >>> [mailto:[email protected]] >>> Sent: Fri, 25 Feb 2011 >>> 09:32:57 -0800 >>> Subject: RE: QUICK question... A/C adapters >>> >>> >>> > I go with 3rd party when there is a significant cost savings. Case in >>> > point, we use a particular print server. The power supplies are >>> > notorious for going bad. We cannot purchase the OEM power supplies >>> > alone and the entire package runs about $120. I found replacement >>> power >>> > supplies for $7.50 online. Just make sure that the voltage, current, >>> > polarity, and the connector size all match up! >>> > >>> > I have been known to go slightly higher in the current capacity so >>> they >>> > don't run as hot. Note that I said "slightly". >>> > >>> > -Paul >>> > >>> > -----Original Message----- >>> > From: John Aldrich [mailto:[email protected]] >>> > Sent: Friday, February 25, 2011 11:27 AM >>> > To: NT System Admin Issues >>> > Subject: RE: QUICK question... A/C adapters >>> > >>> > Thanks guys... I'll keep monitoring, although it sounds like the >>> > consensus >>> > of opinion so far is that 3rd party is OK. :-) >>> > >>> > >>> > >>> > >>> > -----Original Message----- >>> > From: Matthew W. Ross [mailto:[email protected]] >>> > Sent: Friday, February 25, 2011 12:10 PM >>> > To: NT System Admin Issues >>> > Subject: RE: QUICK question... A/C adapters >>> > >>> > *grabbs the "Dell" AC adapter under his desk and checks who actually >>> > manufactured it.* >>> > >>> > It appears that Dell doesn't make their own, this one is made by >>> Delta. >>> > (A >>> > well known PS manufacturer.) >>> > >>> > I'm sure Dell has some very specific requirements for their power >>> > supplies. >>> > >>> > But, I will say that any reputable aftermarket PSs are likely trying >>> to >>> > be >>> > as close to the specs as possible for the intended use. YMMV. >>> > >>> > >>> > --Matt Ross >>> > Ephrata School District >>> > >>> > >>> > ----- Original Message ----- >>> > From: Ames Matthew B >>> > [mailto:[email protected]] >>> > To: NT System Admin Issues >>> > [mailto:[email protected]] >>> > Sent: Fri, 25 Feb 2011 >>> > 08:59:07 -0800 >>> > Subject: RE: QUICK question... A/C adapters >>> > >>> > >>> > > Personally I would get a proper one direct from the manufacturer. >>> You >>> > > hardly want a cheapo PSU bein left on and causing a fire. >>> > > >>> > > Pretty sure that Dell a good few years ago did a recall for a dodgy >>> > > batch of laptop PSU (at least in the UK), I doubt you would get that >>> > > sort of service from an Amazon seller. >>> > > >>> > > >>> > > -----Original Message----- >>> > > From: John Aldrich [mailto:[email protected]] >>> > > Sent: 25 February 2011 16:47 >>> > > To: NT System Admin Issues >>> > > Subject: QUICK question... A/C adapters >>> > > >>> > > Are A/C adapters something you guys would ONLY buy from the OEM or >>> is >>> > an >>> > > aftermarket OK on something like that? I got the OEM to come down >>> > about >>> > > $10, but they're still about $10 higher than Amazon... if you guys >>> > think >>> > > that's something that should come from the OEM, I'll go with them. >>> > I'll >>> > > look for your answers until Monday and make a decision based on the >>> > > consensus of opinion then. :-) (See... I can be patient. :-)) >>> > > >>> > > >>> > > >>> > > >>> > > >>> > > >>> > > ~ Finally, powerful endpoint security that ISN'T a resource hog! ~ ~ >>> > > <http://www.sunbeltsoftware.com/Business/VIPRE-Enterprise/> ~ >>> > > >>> > > --- >>> > > To manage subscriptions click here: >>> > > http://lyris.sunbelt-software.com/read/my_forums/ >>> > > or send an email to [email protected] >>> > > with the body: unsubscribe ntsysadmin >>> > > This email and any attachments to it may be confidential and are >>> > > intended solely for the use of the individual to whom it is >>> > > addressed. 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Si usted no es el destinatario, por favor, póngase en >>> contacto con el remitente por teléfono y destruir todas las copias del >>> mensaje original >>> >>> >>> ~ Finally, powerful endpoint security that ISN'T a resource hog! ~ >>> ~ <http://www.sunbeltsoftware.com/Business/VIPRE-Enterprise/> ~ >>> >>> --- >>> To manage subscriptions click here: >>> http://lyris.sunbelt-software.com/read/my_forums/ >>> or send an email to [email protected] >>> with the body: unsubscribe ntsysadmin >>> >>> >>> >>> ~ Finally, powerful endpoint security that ISN'T a resource hog! ~ >>> ~ <http://www.sunbeltsoftware.com/Business/VIPRE-Enterprise/> ~ >>> >>> --- >>> To manage subscriptions click here: >>> http://lyris.sunbelt-software.com/read/my_forums/ >>> or send an email to [email protected] >>> with the body: unsubscribe ntsysadmin >>> >>> ~ Finally, powerful endpoint security that ISN'T a resource hog! ~ >>> ~ <http://www.sunbeltsoftware.com/Business/VIPRE-Enterprise/> ~ >>> >>> --- >>> To manage subscriptions click here: >>> http://lyris.sunbelt-software.com/read/my_forums/ >>> or send an email to [email protected] >>> with the body: unsubscribe ntsysadmin >>> >> >> >> >> -- >> Jonathan, A+, MCSA, MCSE >> >> ~ Finally, powerful endpoint security that ISN'T a resource hog! ~ >> ~ <http://www.sunbeltsoftware.com/Business/VIPRE-Enterprise/> ~ >> >> --- >> To manage subscriptions click here: >> http://lyris.sunbelt-software.com/read/my_forums/ >> or send an email to [email protected] >> with the body: unsubscribe ntsysadmin >> > > ~ Finally, powerful endpoint security that ISN'T a resource hog! ~ > ~ <http://www.sunbeltsoftware.com/Business/VIPRE-Enterprise/> ~ > > --- > To manage subscriptions click here: > http://lyris.sunbelt-software.com/read/my_forums/ > or send an email to [email protected] > with the body: unsubscribe ntsysadmin > ~ Finally, powerful endpoint security that ISN'T a resource hog! ~ ~ <http://www.sunbeltsoftware.com/Business/VIPRE-Enterprise/> ~ --- To manage subscriptions click here: http://lyris.sunbelt-software.com/read/my_forums/ or send an email to [email protected] with the body: unsubscribe ntsysadmin
