Abstract: Provided are an electric device and an electric device system. The electric device is provided with a battery pack attachment part, main LEDs, and a sub-LED. The main LEDs are lit by electric power from a battery pack. The sub-LED illuminates the battery pack attached to the battery pack attachment part or the battery pack attachment part. The sub-LED is lit when the voltage or capacity of the battery pack is below a predetermined value. The sub-LED is lit by electric power from a power supply part different from the battery pack.

Abstract: A receiving apparatus that includes a first and second filter circuit. The first filter performs filtering on a frequency signal with a band-pass characteristic such that a frequency band of a desired channel is included in a passband, thereby obtaining a pass frequency signal. The second filter performs filtering on the pass frequency signal with a filter characteristic such that a frequency band of a channel adjoining the desired channel is included in an attenuation band.

Abstract: A receiving apparatus that includes a first and second filter circuit. The first filter performs filtering on a frequency signal with a band-pass characteristic such that a frequency band of a desired channel is included in a passband, thereby obtaining a pass frequency signal. The second filter performs filtering on the pass frequency signal with a filter characteristic such that a frequency band of a channel adjoining the desired channel is included in an attenuation band.

Abstract: A modulation circuit includes a band restriction filter 2, an attenuator 3, a modulator 4, a reference voltage generator 8, a comparing reference voltage generator 9, a voltage comparator 10 and an attenuator controller 7. The band restriction filter 2 receives modulation data. The attenuator 3 is connected to the band restriction filter 2 for adjusting its attenuation in response to an attenuator control signal. The reference voltage generator 8 is connected to the attenuator 3 for providing a reference voltage independent of a temperature and a power supply voltage to the attenuator. The comparing reference voltage generator 9 is connected to the reference voltage generator 8 for providing a comparing reference voltage independent of the temperature and the power supply voltage. The modulator 4 is connected to the attenuator 3.

Abstract: A modulation circuit includes a band restriction filter 2, an attenuator 3, a modulator 4, a reference voltage generator 8, a comparing reference voltage generator 9, a voltage comparator 10 and an attenuator controller 7. The band restriction filter 2 receives modulation data. The attenuator 3 is connected to the band restriction filter 2 for adjusting its attenuation in response to an attenuator control signal. The reference voltage generator 8 is connected to the attenuator 3 for providing a reference voltage independent of a temperature and a power supply voltage to the attenuator. The comparing reference voltage generator 9 is connected to the reference voltage generator 8 for providing a comparing reference voltage independent of the temperature and the power supply voltage. The modulator 4 is connected to the attenuator 3.