This 4 -digit 7-segment display section is wired around four common-cathode 7-segment LED displays, and four BC547 npn transistors. The 1K resistors are used for base current limiting, and the 390R ...

Available in 3, 4, or 5-digit varieties, these multiplexed 7-segment displays provided countless hours of entertainment to those who would spell upside-down words on their pocket calculators.

It’s based on several 4-digit seven-segment displays controlled by an AVR128DA32. Navigation is just a few push buttons and a buzzer to let you know when you’ve won.

So, how much less? I started with a basic look at the standard seven-segment digital display (Figure 2). Going through all possibilities of 0 through 9 displayed, it is obvious that the segment “on” ...