Using a laser pointer and a matrix LED as a two-dimensional input device (2010)
cs.cmu.edu
cs.cmu.edu
https://cs.nyu.edu/~jhan/ledtouch/index.html
A few days ago, a user here also commented on how LEDs work both ways and how he used this effect to automatically adjust the brightness of an LED to ambient light. You can find that comment here:
“…and in my next video I’ll show you how to bake a pizza in your freezer.”
My understanding is heat pumps can move more heat energy in/out of a system than the electrical energy input into them. My peabrain logic thinks, "Wait a moment, doesn't that mean a heatpump oven would be more energy efficient than a conventional electric oven with resistive heating?"
I'm assuming the problem lies somewhere in refrigerants not, uh, behaving well at oven temperatures?
The refrigerant gas failing isn't actually a problem for high temperatures. They are a problem to getting too cold, but if you get hot enough, anything will work. Even if it burns down inside your pipes, the results will still work (but your pipes won't).
You can reach home cooking temperatures reasonably easily, and probably even large ones. It's helpful that the compressor only has to deal with gases after they got cooled and heated again on the open air, all the really hot parts are rigid tubing.
There will be problems turning the compressor off, dealing with the heat that propagates back through the pipes. You can solve them with some usual cooling devices (heat disipators, fans, etc).
With reverse-biased diodes, you are operating in photoconduction mode. If tightly-coupled to a fiber optic, and with a quantum efficiency of say, 10%, that would mean for every 10 photons which come in, you get 1 electron charge of current flow.
IIRC there are people who paint e.g. 1N4444 diodes with black paint to minimize opto-induced leakage.