Parts List - Mod-16 counter (74163) - NAND gates (7400) - 3-pronged momentary switches - Or gates (7432) - D-Flip Flops (7474) - 2-to-4 Line Demultiplexor (74155) - Inverter (7404) - Optical isolators - Radio Shack's music kit - 555 timer - Voltage regulator