| 摘要 |
PURPOSE:To easily distribute the pattern of a printed board and to set easily a circuit constant as to the initial clearing circuit composed of a Zener diode ZD2, resistance, capacitor, and transistor (TR) by connecting the cathode side of the Zener diode ZD2 to +Vcc. CONSTITUTION:When the power source is turned on, Vc and +Vcc rises according to constants. When +Vcc rises up to the Zener voltage of the Zener diode ZD2, a current begins to flow through the Zener diode ZD2, and the potential at a point A' rises according to the constant of CR. When the potential at the point A' exceeds the threshold voltage of a TR1, the TR1 turns on and a constant- period reset signal is generated as an output. Thus, the circuit is constituted with one power source of +Vcc and a selection of the ratio of the Zener voltage of the Zener diode ZD2 is made relatively easily and the circuit constant is also set easily; and a Vc power source is not necessary, so the pattern setting of printed board is facilitated. |
