why do TV remotes get “weak” when the batteries start running low?


I’d instinctively expect it to be more of a binary thing: they work, then when the batteries get to a certain level they completely stop working.

Instead you get this in between phase when the batteries start getting low, where you have to get closer to the TV for them to work. Why?

In: 5

Most television remotes work by flashing an ~~ultraviolet~~ infrared light on the front which is seen by a receiver on the TV. A weak battery means a dim light that can’t be detected from as far away.

Same as why a light on battery starts to get weaker and weaker untill it stops. The energy difference between + and – gets lower so their is les current flowing and therefore the signal (infra red light) gets emitted with less power.

The real world isn’t binary, hardly any of the time. The real world is analog all day long.

Your remote control wants to send a flashing light signal to the TV. The electricity from the battery powers an LED that lights up. As the batter is producing less than it’s rated electric current, there isn’t enough light to make the LED light brightly. But, it’s enough to make the LED light dimly. That dim LED might be bright enough for the TV to see and understand it, some of the time, if it’s held closer, …

Why does your car get weak when you start running out of gas?

On a conventional TV remote, when you press a button, you’re just completing a circuit for something that controls a non-visible light at the end of the remote. In the same way that a flashlight will get dim as its batteries die, the light on the remote won’t be as strong when the batteries start to go for it. As the light gets weaker, the TV can’t necessarily see it as easily.