macfidelity

If you want to change the backup interval of Time Machine do the following steps:

• Goto Finder
• Navigate to: /System/Library/LaunchDaemons/
• Backup the file: com.apple.backupd-auto.plist
• Open: com.apple.backupd-auto.plist in a text editor.

The file should look like this:

<?xml version=”1.0″ encoding=”UTF-8″?>
<!DOCTYPE plist PUBLIC “-//Apple Computer//DTD PLIST 1.0//EN” “http://www.apple.com/DTDs/PropertyList-1.0.dtd”>
<plist version=”1.0″>
<dict>
<key>Label</key>
<string>com.apple.backupd-auto</string>
<key>ProgramArguments</key>
<array>
<string>/System/Library/CoreServices/backupd.bundle/Contents/Resources/backupd-helper</string>
<string>-auto</string>
</array>
<key>StartInterval</key>
<integer>3600</integer>
<key>RunAtLoad</key>
<false/>
<key>KeepAlive</key>
<false/>
</dict>
</plist>

The relevant part is the key: StartInterval. Change it’s integer value like you want. The default value in 10.5.2 is: 3600, which means 3600 seconds or 60 minutes.

Based on this article on macosxhints.com