| 摘要 |
PURPOSE:To obtain a device which is highly efficient, is scarcely heated, is simple in circuit configuration, and is long in battery life, by detecting a variation of a load current due to variation of a load, and converting a boosted output to a constant-current. CONSTITUTION:When a transistor Q3 is off, a diode D2 conducts by counter electromotive force of a choke coil L1, and a capacitor C3 is charged and boosted. By charge which has charged the capacitor C3, a current is supplied to a load resistance RL. When a load current flows, it is changed to a voltage value by a current flowing to a resistance R3. When a Zener diode ZD is turned on by some voltage having said voltage value, a transistor Q4 is turned on, too. Since a base current flowing to a transistor Q2 is reduced, the transistor Q2 is turned on easily, and an on-period of the transistor Q2, that is to say, an off-period of an oscillating output is extended. |
