Supply circuit for flash light - automatically measures mains voltage and has relay circuit to change transformer tapping accordingly

摘要

The supply circuit for a flashlight allows the flashlight to be operated from mains supplies of different voltages using a simple automatic changeover switch. The changeover switch consists of a relay (7) whose contacts (4) connect the supply circuit to various tappings along the mains transformer's primary (6). he relay is operated by a voltage detector (11-16) that automatically measures the mains voltage and changes the contacts over if necessary. The relay is only activated if the mains voltage is smaller than the maximum permissible.