# How should i decide resistor and capacitor for IR reciever and feedback LED?

Hey all,
total newbie here, i am planning a project to control my PC with an IR TV remote and have some questions about how to get the proper resistance on IR reciever and LED feedback light. I did not calculate such a thing since high school and as a proper eastern european education system... it was just on paper.

Because it is dirty cheap and i am not familiar with how this will actually work i purchased multiple IR reciever (2 p) and LED light (2 p), bare with me please, i will decide later on the go which configuration will be actually be used in the working setup. I will install component on a 5V output.

Soo for the IR reciever i have TL1838 and TSOP4838. Both of these datasheets show that you should operate it with a capacitor and resistor with given values. Should I follow these or get something close to it? Or just leave it out? As i seen on other peoples projects, lots of people just leaves out these from thier circuit. Is there any risk? Why should i consider it or why can i left it out?

For the LED i am pretty sure i should use one, but not sure exactly which would be safe.

1. LED 1: 254VD1E-V1-1A

I have Forward Voltage 2V as the datasheet states and 25mA current. So if I have a 5V output than (5-2)/0,025=120 Ohm. I am safe to assume if i use 220 Ohm resistor i can use the circuit and have no problem? If I apply the current than i have 5V with 25mA, which means 0,125W so i should get at least a 1/4W rated resistor?

1. LED2: BL-R4530

I have Forward Voltage 2.1V as the datasheet states and 30mA current. So if I have a 5V output than (5-2,1)/0,030=96Ohm. So 220 Ohm resistor with 1/4W power rating should do the trick too?

Am I missing something?

Resistor values for your leds look ok to me.
I have used the TL1838 without the RC filter, as it was mounted next to the MCU. Worked just fine. But since the R and C's are also dirt cheap, I would order a few in case you observe instabillity.

I was surprised how well the IR receiver actually worked.

You should have purchased the similarly cheap IR receivers (3 p) which deliver a digital signal to the controller.

We missunderstand eachother with these abbreviations i think. You reffering to the numbers of pin if i am correct. But as i understand how IR receivers work from my recent readings there is no problem with my choosen IR recievers. I have 3 pin recievers and they carry signal to the controller but 2 p(ieces) as two different kind of IR recievers. Sorry for the confusion. My english is not the best and i understand little to nothing about electrical jargon, i made a confusion if p is short for pin.

Right. I should have seen from the receiver types that these are the ones I mean.

My English is not so good. AFAIR 'pc' or 'pcs' is used for a number of pieces. 'p' for itself does not normally have a meaning.

You are right.

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