h a l f b a k e r y
Funny peculiar.

meta:

account: browse anonymously, or get an account and write.

 user: pass:
register,

# Economical Infrared Sensors

Remote controlled products with infrared sensors that can tell when a remote signal is for that product or another one without using electricity
 (+1, -2) [vote for, against]

When ever you turn on your television with the remote control your VCR has to analyse the flashing infrared signal and determine if it is infact a signal for the VCR. Now, if you have a lot of things in that area that use IR remotes such as stereos, DVD players, Digital recorders (TiVO for example) then you could end up with a lot of machines all using electricity when all you want to do is turn on the TV. Granted the amount of power used is extremely minute, but if everytime somebody turned on their TV that energy was saved we might just be able to add a few nanoseconds more to the time before the light burns out on humanity.

The only thing I haven't figured out is how exactly to get a infrared sensor to only work when the signal is for the device it controls.

I thought that perhaps a humming bird could be taught to beat its wings at the exact frequency of the IR singal for one machine infornt of the other machines' IR sensors so as to block out the light. Now that raises two complications. First, there would have to be one humming bird in front of each machine per each other machine. So you might end up with four humming birds in front of you VCR each beating their wings at different frequencies to block the light from the TV, DVD, Stereo, and digital recorder remotes. The second complication is that the signal frequency for the device you want to control must be such that it occurs when none of the other four signal frequencies do. Otherwise it would be blocked by one of the four humming birds.

Lastly the humming birds must be precise and start flaping their wings at the exact moment a remote is used in order for the frequency and flaping to be in sync.

The major flaw with the humming bird solution is that such highly trained birds aren't stupid and will most likely unionize.

Any suggestions?

 — Tysenworld, Feb 02 2002

 What about remote controls with a very focussed beam and a sight on top to enable you to aim them accurately at a given device without any leakage to other IR sensors?

IR has a wavelength of around 1 to 1000 um, and a frequency of something like 300 GHz to 300 THz. Which is a little fast for a humming bird.
 — pottedstu, Feb 03 2002

That's why I always use decapitated heads.
 — thumbwax, Feb 03 2002

that will get you into trouble with the LAW
 — po, Feb 03 2002

It would be easier (and more economical) for me to take away your remote control(s).
 — phoenix, Feb 03 2002

I like the sighted remotes... You could even make models that look like guns for fun.
 — Tysenworld, Feb 04 2002

 // When ever you turn on your television with the remote control your VCR has to analyse the flashing infrared signal and determine if it is infact a signal for the VCR. //

Is this indeed true? I always thought that the IR devices only detected and reacted to signals specifically for them and nothing else.
 — waugsqueke, Feb 04 2002

 This is not exactly true. All remote controlled apliances have microcontrollers in them, which are like tiny computers.They are basically the brains of the device. they control EVERYTHING in the VCR/TV (and the newer the device is, the more is controlled by the microcontroller). Thus, for the device to be able to respond to it's remote (or even the power button..I said EVERYTHING is run by the microcontroller in a modern VCR or boob-tube), the microcontroller must be turned on the whole time. Different devices may not have different frequencies. The remote sends out a binary datastream (think morse code), which is modulated at around 40Khz (like a radio transmitter). It works somewhat like this(oversimplifying), when a remote wants to send a 1, it will rapidly blink the infrared light at 40Khz (40,000 times a second). and it will not do anything when there is a 0. many devices operate at 40Khz (some work at 39 and 38, and Harmon-Kardon audio gear is at 56KHz..thus it's rare to find a universal remote that supports them). Inside the tv or vcr, there is a detector/demodulator module (looks like a metal box or a big LED with 3 leads). these have an infrared sensor in them and a chip that will demodulate the signal and return the 1s and 0s (like a radio) to the microcontroller. You can get ones (a few bucks from any electronics store or FREE if you drive around on trahs day looking for VCRs) tuned to the various frequencies. They are also usefull for testing if a remote works(hook an LED to the output and give the module 5 volts). Several devices may be on the same frequencies, but the devices may have different codes that they transmit. There are actually several different standards for IR codes. There are a japanese code and a Sony code, etc. One of them (forgot which) would have the first few bytes represent a Device-ID(combination company and model number) and the second set was the function code (like play, volume_up, etc.)

 if you want to know more about IR codes, I have a text file (I forgot the address so I can't post a link, but I have the file) listing all of the IR codes...are you geek enough? mail me if ya want it. nintendork_labs@sbcglobal.net

IR sensors do not take much power. So,in conclusion, the TVs and VCRs always consume power and will not draw any (or much) more power when they intercept a "wrong" IR code. If you want to save power, you could just get "old" style devices without microcontrollers and actually get up off your ass and change the channel. I know these things because I am one of those people who can't look at a (boring old) remote and ask what it would take to turn it into a taser/unlosable remote/unsmashable remote/lightsabre...to me the (from www.repairfaq.org) "world is a toybox full of suboptimised, feature poor toys." what a geek. I also think TVs should come with 10 or more remotes in a TV-mounted dispencer (like for condoms) because I tend to lose/smash/brake/melt remotes
 — dr_photon, Mar 14 2002

And they tend to get confused - I find I can prevent others from changing the TV channel by remote if I point the VCR remote at it with any button held down.
 — neelandan, Mar 14 2002

 Heard of the beat effect? Try playing 2 sounds, one at 440 Hz and one at 441 Hz (you'll need a sound editor to do this, or some tuning forks). You'll notice that the sounds get louder and softer as you play them. This phenomenon has to do with the offset of the waves from each other.

 So: say your TV remote has a frequency of 400 GHz, and your DVD player remote has a frequency of 410 GHz. the hummingbirds will alternately allow and deny the passage of IR beams from your remote according to the difference in frequency between them and the remote you are using. So your VCR might still have to come on every 100 ?s in order to determine whether the incumbent wave was in fact what it was looking for or not.