The second circuit simulates the siren of an American police car. It uses two 555 timers in the circuit. The 555 on the right is wired as an alarm tone generator and the second 555 timer on the left is wired as a low frequency astable timer which generates a ramp waveform of about 6 seconds that is buffered by the transistor and again used to frequency modulate the tone generator. The transistor is used to help strengthen the signal to the speaker

Disable User Account Control (UAC) the Easy Way on Windows Vista

I've previously written about a way to enable or disable UAC from the command line. This is an easier method that you can use to do the same thing from the GUI interface. To recap my earlier article, UAC is ANNOYING.

Note: Disabling UAC will lead to a less secure system, so be warned.

Open up Control Panel, and type in "UAC" into the search box. You'll see a link for "Turn User Account Control (UAC) on or off":

On the next screen you should uncheck the box for "Use User Account Control (UAC)", and then click on the OK button.

You'll need to reboot your computer before the changes take effect, but you should be all done with annoying prompts.