an Op-Amps based "Proximity detector" + alternate sine generator

my 1-st concept of proximity detector ::

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too many components for flame (color temperature (rainbow)) Christmas lights ::

grid:

plot:

 

B4:A4:Y4:X4 -- Red:Green:Blue:Red (!!! a color for the Flame effect -- not generated by this circuit . . .)

trivia:
using switching and level hold the number of chains reduces to one -- it still might be more practical to use AD and DA converters with digital function generators (?EEPROM) , level hold switced output to gain the voltage 2 color effect of your like ... or use 4 differently biased optos or use a fine adjusted PNP NPN chain (cost efficient) , e.c. . . .

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the varying color predecessor of the previous -- an alternative sine generator ::

 

drawing (supposedly) only 125µA from the 5V source

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[EoP]