Andrian decided to modernize his UV exposure box and on par of this was designing new timer circuit. The concept practically remained same – its rather making it nicer and cleaner.
Timer is based on AVR Atmega8 microcontroller, which counts time and displays it on two seven segment displays. AVR is clocked with RTC crystal (32.768kHz). Timer has on-board full-bridge rectifier and 7805 voltage regulator. The lamp load is switched using 5V mechanical relay with basic protection. After timer runs out buzzer alert is raised.