| 摘要 |
<p>A system for deriving a substantially constant output voltage from an alternating supply voltage (S) of variable frequency and amplitude includes circuit (2l, 22) responsive to negative-going zero crossing points (CK) of the supply (S) for generating control signals (T) whose duration depends on the number of points (CK) occurring in a predetermined time. A switching arrangement (l4) is responsive to the signals (T) to interrupt the supply volgage (S), the interrupted voltage being applied through a transformer (l5) to an output circuit (l3) from which a d.c. output voltage is applied to spark igniters (l6).</p> |
