| 摘要 |
<p>Current flow in an inductor (7) from an unstabilised DC-voltage source (4,5) is switched on and off by a series-connected FET (8) under control of a latch circuit (10). The circuit (10) switches the FET (8) off in response to the attainment of a predetermined voltage across a resistance (9) in the series circuit, and switches the FET (8) on again in response to individual pulses of a constant-frequency pulse generator (14). Constant power output of the circuit to power a xenon tube (1) for a flashing-beacon is derived from a capacitor (6) that is charged via a diode (13) from the current-backswing of the inductor (7). The latch circuit (10) may alternatively (Figure 3) be switched off from the voltage across a capacitor (24) in a resistance-capacitance circuit connected in parallel with the series FET (8) and inductor (7), a switch device (26) that shunts the capacitor (24) being operated in unison with the switching of the latch circuit (10), to discharge the capacitor (24) in the intervals between conduction of the FET (8). <IMAGE></p> |
