| 摘要 |
<p>Ignition key contacts (2) include two (a,b) closed in the ''off'' position, completing a circuit (C1,R1) which charges a capacitor to 12v. At switch-on, these open and two others (c,d) close. The voltage across the transistor (TR) control circuit (R2,R3) effectively doubles and the included zener diode (ZD1), previously non-conducting, breaks down, setting base voltage for conduction. The discriminating unit (7) is simultaneously energised (d,f,8) and current flows through the transistor collector and emitter circuit. This effectively connects the collector to frame, together with the detection input (9) to the discriminator, which, recognising an authorised start, switches on a thyristor (SCR) in the coil (4) primary circuit (12), producing the necessary spark (5). Two variants are described.</p> |
