I designed this illuminator to replace an old, beat up, fluorescent ring light on an inspection microscope. It uses a 3.5W, 70 mm OD, chip-on-board LED ring purchased via ebay (2 for $10 including shipping!) and is powered by a 12V wall-wart. The LEDs provide 6500k light so color rendition is good and color coded electronic components can be easily read.
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