LED extinguishment circuit

Published:2011/5/13 3:42:00 Author:Nicole | Keyword: LED | From:SeekIC

In multi-digital display, in order to stress some numbers, so a black out signal is added to this circuit, then the LED will brighten or darken. The principle: LED cathode voltage is dropped from 200V to 100V by Q1, Q2, LED will draken. Control singal is outputed by Q2 base. When the fire extinguishment singal is 0V, Q2 cuts off, LED cathode voltage is 200V. When the fire extinguishment singal is 2V, Q2 turns on, cathode voltage drops to 100V.



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