| 摘要 |
PURPOSE:To reduce the number of terminals and to simplify the operation for changing display level in a level meter in which the stepwise level widths of comparing levels are variable, by making the common use of an input terminal for a change-over control signal for changing the level widths with a terminal for connecting display element. CONSTITUTION:The control input terminal (a) of a level change-over circuit 86 is used commonly for an output terminal 88 for displaying min. level and the contact S1 of a switch 134 is inserted between the terminal 88 and an LED 98 by using said switch. The contact S2 is connected to the earth through a resistor 136 and is connected to the LED 98. In other words, the resistor 136 is connected to the contact S2; therefore if the switch 134 is changed over to the contact S2 side, a bypass for passing the driving current to the LED 98 is formed, and the LED 98 emits light upon receiving the passage of said driving current. Thus, the control input terminal for inputting of the change-over control signal for changing the level width is used commonly with the terminal for connection of display element, whereby the number of the terminals (IC pins) is reduced and the circuit suited for IC is constituted. |
