I am putting a count-down timer by the hardware on Electronic Circuits Application Garage. Time range is 1 minute - 99 minutes. The timer is count-downed every second by hardware timer. During count-down, it controls a voltageless contact. It lights up an LED as the display during control.
http://www.hobby-elec.org/e_pic6_3.htm
This big digital display count-down timer goes to 0 from set time of 1 minute to maximum 99 minutes. It uses the subtraction method for the timer.
http://www.hobby-elec.org/e_counter.htm
Here is a design to turn a cassette recorder on at the times of the BBC Radio 4 Shipping Forecast. It is intended to be used at sea or on a mooring, possibly when the crew are asleep.
http://www.dougrice.plus.com/rt004/ShipTimer/
Short Tutorial on the Classic Timer, the 555. With animations. Also many other circuits based on 555 chip.
http://courses.ncsu.edu:8020/ece480/common/htdocs/480_555.htm
A nice 555 Timer Tutorials with good references.
http://www.williamson-labs.com/480_555.htm
implemented with PIC16F84 and three intelligent 7-segment displays
http://ele.tut.fi/teaching/74470/htyot/r2/index.html
Did you know there are at least 6 different kinds of timers? This circuit implements all of them!
http://www.nutchip.com/progetti/timer_en.htm
schematic
http://www.boondog.com/tutorials/8254/8254.htm