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Frequency generator to shut off street lights.


quantum
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Would anyone have such a clue on how to turn off the light-sensitive street lights? Light toches the photoresistor of the street light and the light goes off and vise versa. Light, I assume, is made up of waves and particles, so would any other type of frequency turn the light off?

It is complete nonsense when those street lights burn during the night and have their streaks of light burst into your house unbiddenly. >:( >:(

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Light has both electromagnetic wave characteristics, but has particle characteristics as well. So, if you think about it, what you are trying to do is basically affect a photocell to switch only based on waves, which will deffinately not work. Photoelectric effect is not based on the wave nature of light on first place - it is based on the particle nature of light. You should know this better than me Quantum ;D. Just kidding :). Unfortunately, you will still have to watch those lights working night time. By the way, only for information, light wave-length is in the nm region... Just calculate the frequency related to this wave-length, and think if it's possible to build this radio-wave transmitter even if this switching was about to work ;)

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Well, particle generator I can think of is only LASER. However, this sounds kind of pointless, right? I mean instead of dealing with laser you can basically turn some lamp on and it will do it ;D. It's true that laser light and regular light are waaay different. LASER is coherent, focused, monochromic.....bla bla, and regular light is a mixture of pretty much any colors. My guess is that this photocell has some filter on it for speciffic light - probably UV since many lamps are filtered from UV light;otherwise it's located somewhere where the lamps themselves cannot illuminate it. In any case you will probably have to climb to illuminate the sensor ;D

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By double hetrojunction laser do you reffer to 2 semiconductor LASER in one body? I didn't say there are not UV lasers - there might be but this is not the point. You will need direct exposure to this light of yours to make the lights turn off. If the sensor is on the top of the lamp, it probably has limiter scope of vision which is simply a tube and the sensor is inside. This way only light at seciffic angle can get in and trigger it. Say in your case they use a cone for the tube - they will have wide enough angle to cover the whole day, but for the lights still to work night time.

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I just wanted to know if laser send out ultra violet rays. Double or single hetrojunction, im just seeing if any laser will work.

the lights stay off until the very last second the sun sets, which means the angle they notice(sensor) the light is around 90 degrees. The street light isn't to far from my house, I could possibly become eye level with the sensor on the roof.

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The LASER light wave-length is more based on the chemical properties that on junctions. There might be UV LASERs, but keep in mind any LASER different than red color 630 -680nm up to 5mW is very expensive, meaning any other light different than red on LASER is expensive on first place. The other thing is that this beam has to be perfectly illuminating the sensor. What I mean is that LASERs are focused into a tiny beam meaning that the illuminated area is small. The other problem if you use LASER is that UV as you know is invisible for your eyes, thus this makes it extremely hard to allign the beam without equipment. The most important thing is that you don't know if the sensor is particularly sensitive to UV only - it is only a guess. If it's not sensitive to UV only, then you can use any focused beam from light with the same sucess :).

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Hi.

I'd point a bright focused flash light to the sensor and see if it shuts the light off. If it does, the sensor isn't UV-only-sensitive (and I don't think it is). Of course, you'd still have to figure out how to trigger the sensor on an every night basis.

But are you sure that you can take the responsibility of shutting a street light off? If there's really no point in having that street light burn all night (which costs your city money), have you considered talking to your municipality (or whetever)?

P.

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Of course, you'd still have to figure out how to trigger the sensor on an every night basis.
P.


Excellent point Peter G. I have thought about that. Your right that does sound somewhat foolish, Ha. However, just having the knowledge to shut the street light off would be cool enough. Knowledge is Power. Also, the street light does a lot of horrible things, not counting shining into my bedroom at night (which I tried to fix with curtains and what not), but also I am a astronomy entusiast. Which you can propably guess, I don't want any light into my telescope! If I could shut it off, I would propably use it when I'm scoping the skies. Having it off all night might be suspicious to the neighbors.

I accicdently found a frequency chart.

I will give you guys a broad description. Infared electromagnetic spectrum (es) is in the Terahertz, wavelenght is 10^-4 meters, and photon energy is 10^-21.
Light is 10^15 freq., i micrometer, and a little less than 10^-18 photon energy.
Ultraviolet is around 10^16 freq., 10^-7 meters in wave length and consist of 10^-18 photon energy.

I just read that the sun emits huge amounts of Ultraviolet rays, which are ozone protects us from a lot of it. Guess what also the sun emits, Infared photons, yeah! What device gives off Infared photons, Iknow that burning coals, and heaters do, but I'm not starting a B.B.Q. under the street lights.

Another thing that is on my mind is that why doesn't it shut its own self down since the light is so close to the sensor, which the sensor is on top of the casing (I'll try to get some photos for you guys)? I think the sensor is sensitive to something, which is not its own light! We have stumbled onto a clue. The sensor are pretty strong/sensitive, so why doesn't the other street lights shut it down? Hmmm?!
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Quantum, the other street light doesn't turn those off because the sensors have a limited scope of vision probably as I said before. They simply don't get exposed to any light from the other lamps (as we all know light follows only stright path). About the UV sensitivity, sensors are usually not built for UV sensitivity only. However, the selection of a single wavelength is fairly simple - they only need one plastic filter in front and voila - there they have it UV sensitive only ;D. I don't believe they use this technique though because the limited scope of vision is more than enough for this trigering to work.

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you could allways go to home depot and invest in some blinds..
$3.50 , problem solved


Outstanding idea! GEE! Why didn't I think about that before? Maybe because I already dark blinds and dark curtains, HA!



street light does a lot of horrible things, not counting shining into my bedroom at night (which I tried to fix with curtains and what not), but also I am a astronomy entusiast. Which you can propably guess, I don't want any light into my telescope!
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Outstanding idea! GEE! Why didn't I think about that before? Maybe because I already dark blinds and dark curtains, HA!




if the sensor isnt facing your house your outta luck..if it is facing your house you could use your vampire powers ..and 'WILL' it to turn off :P :-*
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the sensor in the streetlight is a cadmium sulfide photocell.
this site says that the wavelength response of a cadmium sulfide photocell is 550 to 650 nm.
http://www.chartlandelectronics.co.uk/pdfs/N5AC-501085.pdf

this one says that an infrared laser diode has a wavelength of 785 to 830 nm..
http://www.photonic-products.com/products/receptacled_laser_diodes/rec_infrared.htm

so the infrared option is a bit out of range of the cadmium sulfide photocell .

did ya ever try a red laser pointer..?

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Input voltage does not affect the wavelength of any monochromic light emitting devices. What it could possibly affect is the intensity, but nothing more. Some laser pointers are rated between 630~670nm meaning it COULD do the job for ya. If you can emmit a regular white light you will have pretty much the full spectrum of wavelengths, thus the one that you need as well. There are fairly powerfull white LED that are nothing else but 3 LED sharing the same package - RGB (colors). I have seen this type of LEDs with 20000mCd intensity which is, oh well, enough to cause demage to your eyes. If you can focus this into a nice concentrated beam...you might be able to have fun with no lights on ;D. I personally have tried 10000mCd - it is a lot....especially for a LED 8).

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Outstanding idea! GEE! Why didn't I think about that before? Maybe because I already dark blinds and dark curtains, HA!



street light does a lot of horrible things, not counting shining into my bedroom at night (which I tried to fix with curtains and what not), but also I am a astronomy entusiast. Which you can propably guess, I don't want any light into my telescope!




The only real solution: move away from the city.
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Kain, you say that you have seen leds with 20000mCD. For what unit is that?

I am already ahead of you. I am to recieve a laser pointer that gives off 650nm wavelenghts. I "won" it on 10/06, and is being shipped from Hong Kong. It should arrive within 10 days, which I will tell you of my result.

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Kain, you say that you have seen leds with 20000mCD. For what unit is that?

Quantum, mCd stands for microcandela - unit for light intensity. I guess the "m" should look little different for micro, but we are limited by the software :). Cool about the pointer. It better work too ;D
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