If you've been using seven-segment LED numeric displays and wished you had something larger, then one of the latest entries in the Freetronics/Instructables competition will be of interest. Created by Instructables member frankenroc, the display reproduces the theory of seven-segment displays - but instead uses LED strips for each element.
Naturally you can't drive all those LEDs directly from Arduino digital output pins, so the design uses higher-current switching transistors which do the job nicely. Once complete, this would be idea for a scoreboard, expanded to make a large digital clock or a countdown timer for various events.
If you're making a similar project and need to control large currents with your Arduino digital outputs - you'll need a MOSFET. We've got you covered with out NDRIVE: N-MOSFET driver/output module:
This high-power N-MOSFET module lets you switch high-current loads using a tiny microcontroller. Perfect for controlling that set of traffic lights mounted in your living room! Works brilliantly for automotive projects such as switching high-power 12V lights and high wattage LEDs. For more information and to order, visit the product page.