The LED is the component on the left; there's a very dim flash (pretty much just the black die turning red) at around 11s, then every few seconds.
I can't remember exactly how it works... I think there's two capacitors charged up to the voltage of the LED in parallel through high-value resistors, and a circuit that shorts the +ve of one to the +ve of the other to put them in parallel.
It only just works at a very specific light level. IIRC some of the transistors are used as very low leakage diodes rather than transistors, as the regular diodes I had we're too leaky.
Cool, it's a self powered light meter. The more light there's in the environment the more frequent the blink. Maybe can be adjusted to have less frequent, shorter lasting but more powerful flash!
Many electronics work that way. Motors can also generate electricity. Inductors can create or sense magnetic fields. Resistance is generally temperature dependent. Etc.
Well, pairing the TV with a light sensor in a fixed location, and like, having the tv alternate between a sequence of different patterns, and recording how this changes the reading of the light sensor, and assuming that the room is otherwise dark, uh, apparently can be used to produce an image of the room as if taken from the location of the tv and illuminated from the position of the light sensor?
Ok. Most TVs are equipped with an IR sensor, so with a slightly more capable one you could take an image from the pov of the TV, and illuminated from the TV. Yikes.
Speed of light is fast, even if possible you'd be looking at a lot of conversion losses. It'd be like trying to use a wire as a battery because power has to travel from one end to the other
I’ve heard of materials that can slow down the speed of light propagation. Imagine you can slow the speed of light to a crawl. You shine a huge amount of light into this material, which has a mirror on the other side. Before your light arrives back at the source, swap it for a mirror. You’ve now got a huge amount of light energy trapped.
Okay, I imagined it. Converting electricity into light is inefficient (maxing out around 44% [1] excluding ballast losses), and converting light into electricity is also inefficient (topping out at 47%[2] efficiency). So you'd end up with a battery that stores energy at extremely low efficiency (less than 21% combined), relying on a hypothetical exotic material that can slow light transmission to ~0.00000001c, assuming you don't mind using a hypothetical box that is 1km long, and you can shine the light and replace the light with a mirror in <1 second. And that's before even accounting for the fact that perfect mirrors do not exist, so you'd be losing another 0.1% of remaining energy with every cycle (i.e. every second)
Or you could buy a lithium-ion battery off the shelf today at 95% round trip efficiency and low self discharge.
Another piece to think about is density. Even with these losses.. how much energy can a material hold in terms of pure light? Is there a limit to how much light can pass through a material?
And I wonder if you could slow the light down even further, maybe 2 or 3 more orders of magnitude..
There are actually flow meters that make use of this. They heat the thermocouple using itself, then switch back to using it as a thermocouple and measure the rate of heat dissipation and correlate that to flow rate.
https://youtube.com/watch?v=BM7VDOoFIWI
The LED is the component on the left; there's a very dim flash (pretty much just the black die turning red) at around 11s, then every few seconds.
I can't remember exactly how it works... I think there's two capacitors charged up to the voltage of the LED in parallel through high-value resistors, and a circuit that shorts the +ve of one to the +ve of the other to put them in parallel.
It only just works at a very specific light level. IIRC some of the transistors are used as very low leakage diodes rather than transistors, as the regular diodes I had we're too leaky.