You can eschew expensive dc/dc converters by using this inexpensive circuit to drive a white LED from a single battery cell

AuthorsSusanne Nell
Main DocumentArticle «Voltage-to-current converter drives white LEDs»
DescriptionFigure 1
File Format / SizePDF / 19 Kb
Document LanguageEnglish

You can eschew expensive dc/dc converters by using this inexpensive circuit to drive a white LED from a single battery cell