Build a switch circuit that responds to sharp sounds like clapping your hands, etc. * Class pack of 20 kits * Kit contains all components including circuit board * 3A changeover relay output * Circuit counts two claps before operating to avoid false triggers * Operates from 6 to 20V * Component count 36 * Circuit board dimensions: 55 x 50mm * Money-saving classpack of 20 kits packed in a Gratnells tray Suitable for Key Stages 2, 3 & 4 (ages 7 to 16) Teachers notes are available to download at our Education Resources site.