Loss prevention warning device for mobile telephone alerts user if distance between high frequency transmitter and receiver exceeds certain value

摘要

The warning device includes a transmitter (1) having an oscillator (11) and an amplifier (12) and being controlled by a switch (22) to emit high frequency carrier wave signals. A receiver has an amplifier, a wave detection multiplier, an oscillator, a switching circuit and a buzzer or vibrator. The receiver receives the carrier wave signals from the transmitter in such a way that the transmitter is no longer capable of communicating with the receiver using the carrier wave signals if the distance between the transmitter and receiver exceeds a certain value. If this is the case, the receiver vibrates or buzzes to alert the user. The transmitter is connected to the battery circuit (2) of the mobile telephone and is supplied by its battery. The receiver may be provided with a clip or chain for attaching to the user's waist or bag.