| 摘要 |
PURPOSE:To prevent the breakage of a speaker due to an erroneous operation by controlling the supply of a power source electric power to, for instance, a channel divider, low frequency amplifier and high frequency amplifier, or the order of the interruption only through such operations as closing and opening one power source switch. CONSTITUTION:When a power source switch 4 is closed, a transistor 11 is turned off, and a voltage of a positive E is inputted to an operational amplifier 15 through resistances 12 and 13, inverted and amplified. Then the transistor 11 executes the integrating action for charging gradually a capacitor 14. Thus a control signal Vc rises slowly from a Vl up to a Vh through Vc1-Vc3. When an output at ''H'' level is received in terms of a switching means 7a, the output is inverted to ''L'' level by an inverter 20, and a relay 21 is driven to close a node 21a. In terms of switching means 7c and 7d and same action is executed, nodes 21a, 24a and 27a are closed in the order that inputs from delay circuits 6a, 6c and 6d come to ''H'' level. Power source electric power is supplied to a channel divider not shown in the figure, low frequency amplifier and high frequency amplifier, in this order. |
