Do I have to use a resistor to connect the IR receiver?

Hi.

I want to connect the IR receiver to the Arduino Uno. Do I need to use a resistor?

Thanks.

which IR receiver?

My receiver is TSOP1838.

The datasheet gives you a hint

So if you want the best setup, you need 2 resistors and a cap. but as stated they are just "recommended"

You should be fine if you just connect Vcc, GND and the out pin back to your arduino (and trust the Arduino so that you don't get power supply disturbance)

Thanks

I have one more question. I connected the IR receiver. If I do not press any buttons on the remote control, I have 5v on the signal pin. If I press a key, I have 4.5V. Does everything work as it should?

The output pin is not a pure DC stable signal - so not sure how you are measuring this.

Hook up an oscilloscope to see what’s going on

Thanks. The receiver is working.

Enjoy