5 mm IR Transmitter and Receiver LED Tx Rx Pair Photodiode

[runaway_pancake]

You could still use TV remote-based components, but you would have work within that scheme.
There's a rate where 38kHz bursts can be sent repeatedly and still not 'overload' the receiver module.

[octopirate]

@Wawa

TSSPxxxx sensor instead of TSOPxxxx.

Ah, I mentioned earlier* there was a difference, but couldn't for the life of me remember how to identify them by name. Have copied that nugget into my Arduino stuff text file. Thanks.

(* Well earlier in time, but this thread is confusing now since OP started another one and the mods rightly joined them.)

[octopirate]

@kolaha

translucent one as normal LED and dark one as input

I know it says that on the page OP linked, but all the ones I used before are opposite: the dark one is the led and the clear one the receiver.

@kolaha

nothing special.

Well it's a bit special: The receiver should be reverse biased in a divider and the signal read at the mid-point:

source

[kolaha]

@octopirate

the dark one is the led and the clear one the receiver.

no.

and wiring can be inverted.

[octopirate]

@kolaha

no.

Don't contradict me when I'm saying for a fact, that (and I quote) "all the ones I used before are opposite", note the emphasis, and here's a photo:

[kolaha]

so good photo. of course i am convinced.

[octopirate]

@kolaha

of course i am convinced

I don't give a rat's if you're convinced or not; the fact is that for the ones I have used before, the dark one is the light. I was merely making that point. I am not saying, nor am I saying, that the web site is wrong, nor am I saying you're wrong.

[kolaha]

Are IR phototransistors always dark, are IR LEDs always clear?

[6v6gt]

@runaway_pancake

You could still use TV remote-based components, but you would have work within that scheme.
There's a rate where 38kHz bursts can be sent repeatedly and still not 'overload' the receiver module.

Indeed. I've used a TSOP4838, which is designed for compatibility with TV remote controls, in a beam break application. There I had to modulate the beam at 38kHz and send 600us carrier bursts each followed by something like a 600us pause. The data sheet states the relationship between the bust length and minimum pause. The reason for this is that any continuous signal is treated as interference (as say from a fluorescent light) and tends to be filtered out.

from https://www.mouser.ch/datasheet/2/427/tsop48-1766935.pdf

[Wawa]

@6v6gt

The reason for this is that any continuous signal is treated as interference (as say from a fluorescent light) and tends to be filtered out.

Close...
TSOP receivers have AGC (automatic gain control).
They turn down amplification until no signal is received, to block out background noise. Short powerful pulses (remote) can still come through.

Downside from a heartbeat-based beambreak is the slightly longer reaction time.
Leo..