It’s back! The 555 timer contest wants to see you do something cool with the 555 timer chip. At stake is the adulation of electronics geeks everywhere. Three top winners will be awarded a $150 ...

[R-B] designed a 555 timer circuit to scan a keypad. Keypads are common interfaces for small projects and require row and column scanning by a microcontroller. [R-B’s] setup allows you to reduce ...