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Required thermal resistance (red or amber) = (50-35)/4.62 = 3.24 C/W
Required thermal resistance (white) = (50-35)/6.09 = 2.46 C/W
https://www.digikey.com/product-detail/en/ohmite/PA-T2X-38E/PA-T2X-38E-ND/9607314 (two for each LED board will result in an equivalent thermal resistance of <4 C/W)
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