>Nah, I don't buy it. If you supply an over-rated voltage to digital >electronics, you have a very strong chance of burning them out. > >Try sticking a light bulb on a very high voltage - the bulb burns >out. The current through the filament was strong enough to literally >burn the filament. The same is true with an LED in series with a >variable resistance resistor - turn down the resistance and the LED >gets brighter.
etc etc actually, he was talking about CURRENT, not voltage, and he was correct: a circuit will only draw what it needs (barring a short or faulty component) from a power supply, so it is safe to hook up a device requiring say 1A at a given voltage, to a power supply capable of delivering 10A at the same voltage. The circuit will only draw 1A , and no harm is done. This no longer applies IF you have say, a shorted capacitor in the power supply for instance, but the unfortunate results of that scenario would be similar regardless of the current supplied. Well-designed power supplies incorporate a "crowbar" circuit, which will limit the current, or shut off the supply in the event of a short. I have used 170 and 190 supplies to power my 145, and have had no problems. I also designed a power supply for my car, which outputs 7.5VDC at 3.0A (regulated and nicely filtered) for my 145, from the nasty spikey variable voltage provided by the alternator. This works very well, and testing with an ammeter revealed that the 145 draws around 2.7A at startup, which quickly drops to an average of about 1.75A (with the HD on, screen backlighting on, and the battery charging). I even incorporated a simple diode bridge that allows my supply polarity to be accidentally reversed without damage! You're right, of course, about voltage! Supplying a higher-than rated voltage WILL fry your circuit. m PS anyone interested in battery-rebuilding or Powerbook supplies can view my lengthy posts on this for detailed instructions, in the archives (umm, I believe that was about a year ago), and the Pickle kindly reposted some of this on his site as well. -- PowerBooks is sponsored by <http://lowendmac.com/> and... Small Dog Electronics http://www.smalldog.com | Enter To Win A | -- Canon PowerShot Digital Cameras start at $299 | Free iBook! | Support Low End Mac <http://lowendmac.com/lists/support.html> PowerBooks list info: <http://lowendmac.com/lists/powerbooks.shtml> --> AOL users, remove "mailto:"; Send list messages to: <mailto:[EMAIL PROTECTED]> To unsubscribe, email: <mailto:[EMAIL PROTECTED]> For digest mode, email: <mailto:[EMAIL PROTECTED]> Subscription questions: <mailto:[EMAIL PROTECTED]> Archive: <http://www.mail-archive.com/powerbooks%40mail.maclaunch.com/> Using a Mac? Free email & more at Applelinks! http://www.applelinks.com
