There are many uses of countdown timer. It can be used for PCB development, in a kitchen or during workout. All you need that timer was easy to set up and start. Umetronics have build simple PIC16F886 based countdown timer with four bright 7-segment displays.
LED displays are driven using TLC5916 LED driver and couple dual P-channel MOSFETs. Time can be selected with rotary encoder which comes with button for select. When timer runs out there are two options for notifying – one is display flashing and another micro-switch selectable sound option along with green LED indicator. Sometimes sound might be annoying, so you can always turn it off. Timer is two AAA battery powered. So it is small portable timer for any use.