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Using a laser pointer and a matrix LED as a two-dimensional input device (2010)

cs.cmu.edu

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Re: Using a laser pointer and a matrix LED as a two-dimensional input device (2010)

#11

Post by spijdar »

nayuki wrote: post #7
shreddit wrote: post #4

Earlier quoted context omitted.

Very impressive, i love this kind of stuff. “…and in my next video I’ll show you how to bake a pizza in your freezer.”

Just swap a couple of pipes to reverse the heat pump. Nothing can possibly go wrong.

...okay, but could this actually work? I'm assuming because there are no products like this that there's a giant caveat somewhere, but isn't it actually a good idea?

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?

Re: Using a laser pointer and a matrix LED as a two-dimensional input device (2010)

#12

Post by marcosdumay »

nayuki wrote: post #7
shreddit wrote: post #4

Earlier quoted context omitted.

Very impressive, i love this kind of stuff. “…and in my next video I’ll show you how to bake a pizza in your freezer.”

Just swap a couple of pipes to reverse the heat pump. Nothing can possibly go wrong.

It has a way to push heat into it, some heat insulation, a door, and it's food-ready. The thing is basically an oven already, and 270K and 400K are just some 30% change.

Re: Using a laser pointer and a matrix LED as a two-dimensional input device (2010)

#13

Post by marcosdumay »

spijdar wrote: post #11
nayuki wrote: post #7

Earlier quoted context omitted.

Just swap a couple of pipes to reverse the heat pump. Nothing can possibly go wrong.

...okay, but could this actually work? I'm assuming because there are no products like this that there's a giant caveat somewhere, but isn't it actually a good idea? 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 electri…

You will be able to reach small ~100°C heating before everything starts failing and getting on fire, then you will get much larger temperatures, once. If you have a bad enough circuit breaker, you may even reach metallurgic oven temperatures for a short while!

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).

Re: Using a laser pointer and a matrix LED as a two-dimensional input device (2010)

#14

Post by spijdar »

marcosdumay wrote: post #13
spijdar wrote: post #11

Earlier quoted context omitted.

...okay, but could this actually work? I'm assuming because there are no products like this that there's a giant caveat somewhere, but isn't it actually a good idea? 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 electri…

You will be able to reach small ~100°C heating before everything starts failing and getting on fire, then you will get much larger temperatures, once. If you have a bad enough circuit breaker, you may even reach metallurgic oven temperatures for a short while! 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 wo…

Is the problem "literally using a freezer"? Could you (in principle) build an insulated chamber that could deal with the temperatures?

Re: Using a laser pointer and a matrix LED as a two-dimensional input device (2010)

#15

Post by kaszanka »

Moosdijk wrote: post #10
nayuki wrote: post #6

I see they did a trick in the code: Because binary literals were added late in C++14, it seems they used some library which defined 256 constants like B00000000 = 0, B00000001 = 1, ..., B11111111 = 255.

Note quite. See [1] [1] https://www.arduino.cc/en/Reference/PortManipulation

Yes, Arduino is the library that defines these macros: https://github.com/arduino/ArduinoCore-avr/blob/8f8df161ebf3...

Re: Using a laser pointer and a matrix LED as a two-dimensional input device (2010)

#16

Post by marcosdumay »

spijdar wrote: post #14
marcosdumay wrote: post #13

Earlier quoted context omitted.

You will be able to reach small ~100°C heating before everything starts failing and getting on fire, then you will get much larger temperatures, once. If you have a bad enough circuit breaker, you may even reach metallurgic oven temperatures for a short while! 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 wo…

Is the problem "literally using a freezer"? Could you (in principle) build an insulated chamber that could deal with the temperatures?

Ok, the question is if you could build an oven heated by a heat pump? Yes, you could.

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).

Re: Using a laser pointer and a matrix LED as a two-dimensional input device (2010)

#17

Post by elcritch »

_spduchamp wrote: post #5
_Microft wrote: post #3

You might also want to watch this video that demonstrates a 2D proximity sensor using an LED array. It works without a laser pointer, using the fingertips alone is good enough for it: 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…

I've wondered how hard it would be to hack old LED signs into OSC touch control surfaces.

What about modern OLED tv’s? It’d be fun to have a 50” touchscreen.
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