| 摘要 |
<p>PURPOSE:To obtain a timer circuit which features a constant operation time without using any cell voltage and by providing the charge/discharge circuit, the switching element and the driving element and then deciding the charging voltage of the charge/discharge circuit with the forward drop voltage of the driving element. CONSTITUTION:Capacitor 11 is charged when switch 22 and 23 are turned on, and the current flows from the middle point of switch 22 and 23 through the area between the base and the emitter of driving transistor Tr17 and 19. Capacitor 11 is charged with base-emitter voltage 2VBE of Tr17 and 19. Under these conditions, switching Tr14, is off with Tr17 and 19 turned on. Capacitor 11 is discharged gradually with switch 22 and 23 turned off, and then the current path is cut off between cell 1 and circuit 2 with Tr14 turned on and Tr17 and 19 turned off when the potential becomes VBE at point A. Capacitor 11 is charged with 2VBE but by the voltage of cell 1, and the original discharge value is 2VBE and constant. Accordingly, a constant operation time can be secured for ON of Tr14.</p> |
