The battery capacity will be better with lower drain currents. To determine the battery life, divide the capacity by the actual load current to get the hours of life. A circuit that draws 10 ma powered by a 9 volt rectangular battery will operate about 50 hours: 500 mAh /10 mA = 50 hours The cell voltage of alkaline cells steadily drops with usage from 1.54 volts to about 1 volt when discharged. The voltage is near 1.25 volts at the 50% discharge point.
Sometimes building an enthusiastâs PC is more difficult than building a budget one because you have budget, but donât want to go overboard or make decisions that waste money. We hope this sub $1200 build walks the line between spending good money on components that matter without spending too much on the ones that donât.
Windows XP: You're not eligible for a free upgrade to Windows 10, and there's a decent chance that your computer is too old to run the new operating system, which costs $119 for the Home version and $199 for Pro. However, Windows XP no longer receives security updates, so your computer is at risk every day you run it.