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IR Emitter with lm317

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Revathysrini

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Hi,

can you please explain the purpose of lm317 in attached circuit IR CKT.JPG
 

The LM317 limits the current to 26.6mA (1.25V/47 ohms). The 47 ohms resistors in series with each LED are not needed unless the tiny surface mounted LM317 gets too hot.
One resistor can replace the LM317 and the three resistors if the supply voltage does not change too much.
 
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