Abstract: A switching power supply includes a first switching element connected between a primary winding of a transformer for the switching power supply and the ground, a shunt regulator serving as an output voltage detection circuit configured to detect an output voltage on a secondary winding side of the transformer, a photocoupler configured to transmit the output voltage to a control circuit, a second switching element configured to receive a stop signal for stopping operation of the switching power supply, and a photocoupler drive circuit configured such that when the second switching element has received the stop signal, power output from a low-frequency transformer power supply or the switching power supply is supplied to the photocoupler, and the stop signal is transmitted to the control circuit via the photocoupler.

Abstract: There is provided a protection circuit that is mounted between an AC adapter and a load circuit, operates with power supplied from the AC adapter, has a soft start function, and can perform overvoltage protection and the like. An audio device 10 is configured to include a protection circuit 20 at the side of the AC adapter 8, as well as a load circuit 12 that is an audio circuit body and a speaker. The protection circuit 20 includes an input terminal 22 connected to the AC adapter 8, an output terminal 24 connected to the load circuit 12, a power supply line 25 extending toward the output terminal 24 from the input terminal 22, a switch unit 26 and a DC/DC converter 28, the switch unit 26 and the DC/DC converter 28 being provided along the power supply line 25, and a protection circuit unit 30 that detects a voltage state or a current state on the power supply line 25 and protects the DC/DC converter 28 and the load circuit 12.

Abstract: In a network system without a server, a network device and a system that can share information in all devices efficiently and surely are provided. CPUs of a plurality of devices connected to a network determine a host device based on device numbers and network strengths of each of the devices. When transmitting share information stored in a memory to the host device, the CPUs of the client devices merge share information transmitted from the other client devices with the share information stored in the memories so as to transmit the merged information to the host device. The CPU of the host device generates share information about all the devices so as to distribute the information to all the client devices. When the share information is changed, the CPU of the host device generates finite difference information with respect to previous share information so as to distribute the information to all the client devices.

Abstract: In a protection device of a current amplifier circuit, to protect the current amplifier circuit against more high-speed operation than recovery time of a relay device and to protect operation of the current amplifier circuit in a wide range from low frequency side to high frequency side. A protection device 30 includes a detection circuit 32 that detects an abnormal current value of a current amplifier circuit 14 and outputs a first abnormality detection signal. The protection device 30 outputs a second abnormality detection signal continuously for predetermined time that starts from output timing of the first abnormality detection signal, turns down an input voltage value to the current amplifier circuit 14 at receiving timing of the second abnormality detection signal, and outputs a cutting command signal to a relay device 36 at the same timing.