| 摘要 |
PURPOSE:To make sure the operation of a channel selection circuit, by holding the state before the selection when a plurality of channel selection switches are depressed at the same time, then making the channel selection operation surely after the channel selection switch is opened. CONSTITUTION:While a channel selecton switch 1 is closed, a transistor (TR)QA is turned on, a line potential at an output d' is lowered through a diode DA and a control circuit 2' is inoperative and no output b' appears. When the channel selection switch 1 is opened, the TRQA is truned off, so that the power supply voltage is applied to the control circuit 2' as the output d', and the channel selection circuit B follows to select the same channel as the channel selecton circuit A. |
