Electrical whistle used by e.g. referee for making attention of players, has integrated circuit device to produce audio control signal for activating switch such that oscillation frequency of control signal is determined by resistor

摘要

The electric whistle has a sound integrated circuit device (30) that includes power supply terminal (VDD) connected to a power supply circuit (10) for receiving operation voltage and for producing an audio control signal for activating the electrical switch (Q1). The inductance voltage for activating a buzzer (20) is produced if electrical switch is activated. The output adjusting terminals are connected with respective terminals of tone setting resistor such that the oscillation frequency of audio control signal is determined by tone setting resistor (R1).