This tea timer is based on an ATtiny85 running a short C program. The LEDs display the remaining time to wait, the first LED blinking with a frequency 1Hz. They are driven by a counter because of the lack of external pins of the micro-controller. The push switch selects the time delay, the other one switches between setting/running mode. When the time is up, the tune "Tea for Two" is played on the small buzzer. A RC filter is used as integrator to improve the sound quality (the variable resistor is tuned accordingly).