The DC/AC double purpose dark room safelight

Published:2011/7/2 2:25:00 Author:Borg | Keyword: double purpose, dark room safelight | From:SeekIC

This DC/AC double purpose dark room safelight has the function of pointless auto converting switch. It is adopted with orange LED. When the power is normally supplied, the AC 220V is rectified by the transformer, filtered by the capacitor, and then is turned into a 4V or so DC (it's 5V when it is in empty load). As the voltage of the battery in the machine is 3V, the diode D is conducting and powered by the rectifier power supply. As the BG emitter LEV is lower than the basic LEV, therefore, BG is blocked, the battery E is cut off automatically and there is no current out.When the power is off, the LEV of BG emitting pole is higher than the basic pole LEV.



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