Use a IR receiver to collect codes and send them to your TV with an IR transmitter.

Alexa and IR Project:    • Use Alexa to Control your TV!  
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Materials:
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IR Receiver/Transmitter:
https://amzn.to/2YlFDRR
100 Ohm Resistor:
https://amzn.to/2qtCBhS
Arduino Uno:
https://amzn.to/2Ru2sBr
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Sketches: https://github.com/Grensom/IR-Project

IR_REMOTE_read: https://github.com/Grensom/IR-Project...
IR_REMOTE_send: https://github.com/Grensom/IR-Project...