On Tue, 25 Jun 2013 12:17:35 -0400 "P E Schoen" <paul@peschoen.com> wrote in Message id: <kqcfh9$qon$1@dont-email.me>:>Usually the +5V and +12V supplies are fairly high current. And in many cases >only the +5V supply is directly regulated. It might be possible to reverse >the diodes and output capacitor on the +12V supply to make it -12V, and then >you should get 17V between them.IF it's possible, and I have a feeling that it's not, you'd better flip the polarity on the electrolytic caps as well!
DC 17V from PC power supply?
Started by ●June 25, 2013
Reply by ●June 26, 20132013-06-26
Reply by ●June 27, 20132013-06-27
On 2013-06-25, Mr. Man-wai Chang <toylet.toylet@gmail.com> wrote:> On 25/06/2013 8:01 PM, John G wrote: >> NO! >> Shorted is the correct description. >> They are both referenced to ground so MAGIC SMOKE will result. :-? > > OTOH, should I attempt -5V and +12V pins at the power connector? Or > should I try +5V and -12V? > > Which one is safer and could supplies 4A?neither, both -5 and -12 are typically capable of less than 1A (0.2A on a device at hand) -5 has been discontinued in new PCs If you need 17V and 4A you could try an aftermarket adjustable laptop power brick, It might be easier to find one at 18V or 16V though, but there are 17V ones out there. -- ⚂⚃ 100% natural --- news://freenews.netfront.net/ - complaints: news@netfront.net ---
Reply by ●June 27, 20132013-06-27
On Thu, 27 Jun 2013, Jasen Betts wrote:> On 2013-06-25, Mr. Man-wai Chang <toylet.toylet@gmail.com> wrote: >> On 25/06/2013 8:01 PM, John G wrote: >>> NO! >>> Shorted is the correct description. >>> They are both referenced to ground so MAGIC SMOKE will result. :-? >> >> OTOH, should I attempt -5V and +12V pins at the power connector? Or >> should I try +5V and -12V? >> >> Which one is safer and could supplies 4A? > > neither, both -5 and -12 are typically capable of less than 1A (0.2A > on a device at hand) > > -5 has been discontinued in new PCs > > If you need 17V and 4A you could try an aftermarket adjustable laptop > power brick, It might be easier to find one at 18V or 16V though, but > there are 17V ones out there. >Which I find all the time in the garbage. Or that time I needed a power supply for a Powerbook 1400, I opened up an inkjet printer I'd dragged home from the garbage, and it had the right voltage (those tend to have higher voltages than +12, but still decent current). The external power supplies have the advantage that they are already cased. The inkjet supplied a standalone power supply board, making it easy to extract, but not casing. But, the problem is that applying voltage to a battery isn't a good thing, if the battery is some more recent kind, it needs a proper charger. Michael
