A selective call receiver (100) comprises a receiver (104) for receiving a message and a vibrator (116) capable of vibrating at a selected one of at least two selectable frequencies for alerting a user of a received message. The vibrator (116) also has a selector (120) or a tuning element (130) for varying...http://www.google.com.au/patents/US5293161?utm_source=gb-gplus-sharePatent US5293161 - Selective call receiver having a variable frequency vibrator
