Sound and light control switch parts ， circuit design using discrete components ， VT3 light during the day in the conduction state ， the short microphone ， voice circuit does not work. When no light at night ， light-sensitive resistor changes make VT3 is off， the microphone senses sound by amplifying sent VT1 VT2 triggered thyristor . The lamp is lit， the conduction time depending on the parameters R3， C2 to . Packages can only use less than 40W ordinary incandescent bulbs as a load ， overload and can not use energy-saving lamps for the load. Kit is connected with 220V power supply ， installation and commissioning must be carried out under the guidance of professional teachers .