Flash an LED from ac-mains power

摘要

LED technology is opening the door to a variety of high-power-il-lumination applications. The circuit in Figure 1 can let you know when ac power is available. To drive a power LED from the ac line requires a converter or a similar arrangement. In this circuit, a passive dropper greatly simplifies the total design. You can also simplify the circuit to run on dc power, which lets you use it from automotive batteries to supply light at night.