| 摘要 |
PURPOSE:To decrease the number of parts of an ignition circuit and lower its cost, by connecting a by-pass thyristor in parallel with the primary winding of an ignition coil and turning on the thyristor by a voltage corresponding to that induced across the primary winding. CONSTITUTION:A series circuit consisting of a resistor R1 and a thyristor 6 is connected between the terminals A, C of the primary winding 11 of an ignition coil 1 so that the anode of the thyristor is located at the side of the terminal A. The electrode of the N-base layer NB of the thyristor 6 is connected to the base of a transistor Tr2. A parallel circuit consisting of a resistor R4 and a capacitor C1 is connected between the anode of the thyristor 6 and the electrode of the N-base layer NB. When the potential on the terminal A is higher than that on the terminal C, a current flows to the base of the transistor Tr2 through the resistors R1, R4 and the capacitor C1 so that the emitter current of the transistor increases. When the thyristor 6 is turned on as a result of the increase in the current flowing from the layer PE of the thyristor to its other layer PB, the transistor Tr2 is turned off so that sparks are produced on a spark plug 5. |
