Hi noname,
here is my circuit design.
It uses a total of three ICs and five transistors. You might skip the LED driver transistors, resulting in very dim LEDs and no buzzer operation.
The buzzer must be self contained, meaning it must have its own oscillator circuit built in.
Circuit description: IC3 (CD4017) is reset during power up, thus activating Q0 to have the red LEDs D7 through D9 lit.
When pressing the momentary switch S1 the monostable oscillator is activated for 5 seconds resetting IC via T1 at pin4, resulting in no clock pulses to be fed into IC3 (pin14)
After IC1 has timed out IC2 generates pulses (adjustable from 5 to 10Hz using P1) keeping the red LEDs lit for four clock cycles. The fourth clock cycle disables D7, the sixth clock cycle disables D8 and the 6th clock cycle disables D9. The 8th clock cycle finally disables all red LEDs and switches on D7 through D9 green LEDs and simultaneously powers the buzzer.
This condition will hold until S1 is pressed again or S2 (RESET) is pressed. If S2 is pressed the count down will restart, omitting 5 seconds delay to turn off the red LEDs.
The board is purely single sided and measures 99.35X72.35mm (3.91X2.85").
If you want to obtain the Eagle files please PM me your full name and email address.
Boncuk
P.S. Increasing C3 from 1 to 10µF the clock frequency can be varied between 0.449 and 1.192Hz.