PCB developer may find this project very handy, because it has all features needed to control ultraviolet exposure box. Timer does what it has to do – it lights UV lamps ON while counter counts down time and switches lamps off when time reaches zero.
Timer also has a display of 4 seven segment LED indicators where exact time can be viewed. There is also a bicolor led used for indicating timer status (standby and count on). LED display is traced on separate PCB so it could be integrated in front of PCB exposure box. Source code is available in asm language (ready to flash hex as well).