A telephone-answering machine has a switch on it that activates the response message "After the tone, leave a message" after one, two, or four rings....

A telephone-answering machine has a switch on it that activates the response message “After the tone, leave a message” after one, two, or four rings. The incoming signal is a burst of 24 V, 20 Hz AC voltage. Design a logic circuit that will count the rings and furnish signals to the triple-pole-signal throw switch.