WE got radio and microwaves.. now IF and Light?

[VE7NOT]

Read QST magazines from time to time and kept on with a lasre cw and am transciever. That's right red light laser.

I know some do this.

This is of course unregulated area.... for now.

What is hams move to experiment with IF and Light?

What would happen to 100wt wide bands (light bulbs) http://www.qrz.com/iB_html/non-cgi/emoticons/rock.gif

Laser seem more poular then some higher microwave bans. Some have managed with alot of watts to puch thriough clouds at times.

When we come over our neighbours remote for his TV and our house shines red then light will start being regualted I think http://www.qrz.com/iB_html/non-cgi/emoticons/laugh.gif

[AG3Y]

One of the first experiments I ever did for a "Science Fair" back in my highschool days was to try to modulate a lightbulb with an audio signal and pick it up on a photo-cell. I was able to "transmit" the length of our yard with the lash-up.

The biggest problems I had were understanding that the lightbulb had to be biased with a low voltage ( enough to make it glow dimly ) and how to impress the audio on that bias voltage .

Then I had to figure out how to take the voltage from the photo-cell and amplify it enough to feed a speaker.

I did accomplish all of that to a degree, but the results were certainly not what you would call "hi-fi"

Now days, there are infer-red headphones that work with LEDs and SMT devices and put all that electronics inside the cup of the headphone.

I do have a professional grade laser here that can probably shoot a beam - - - well, lets just say a looong way. I have always wondered what it would be like to modulate that sucker and pick up the beam a good distance away. But I'm fairly scared of looking directly at the thing accidently, so it remains safely tucked away in my "future projects" drawer. Maybe some day I will get it out again!

73, Jim

[kl7aj]

Quote[/b] (AG3Y @ June 19 2006,09:31)]One of the first experiments I ever did for a "Science Fair" back in my highschool days was to try to modulate a lightbulb with an audio signal and pick it up on a photo-cell. #I was able to "transmit" the length of our yard with the lash-up.

The biggest problems I had were understanding that the lightbulb had to be biased with a low voltage ( enough to make it glow dimly ) and how to impress the audio on that bias voltage . #

Then I had to figure out how to take the voltage from the photo-cell and amplify it enough to feed a speaker.

I did accomplish all of that to a degree, but the results were certainly not what you would call "hi-fi"

Now days, there are infer-red headphones that work with LEDs and SMT devices and put all that electronics inside the cup of the headphone. #

I do have a professional grade laser here that can probably shoot a beam - - - well, lets just say a looong way. #I have always wondered what it would be like to modulate that sucker and pick up the beam a good distance away. #But I'm fairly scared of looking directly at the thing accidently, so it remains safely tucked away in my "future projects" drawer. #Maybe some day I will get it out again!

73, Jim
I built a solar powered flashlight once, but it didn't work too well in the dark. http://www.qrz.com/iB_html/non-cgi/emoticons/smile.gif

[K7KBN]

Do not look at laser with remaining eye.

[AG3Y]

Pat, this thing has two holes in the case for the light to come out. The weak light end is stronger than those little handheld light pens that kids seem to love to shine around for the cat to chase! You can imagine what the "forward" end is like! I really don't know what the original purpose of this thing was, but the word "metrology" is part of the title. I guess it must have been a standard for some extremely accurate distance measuring device, or something like that.

73, always good to see your remarks! Jim

[kb2vxa]

Hi super ultra extra high frequency fans,

Gee, the miliary can shoot down missiles with an IR laser, what's the prefix for Alpha Seti 3? A friend and I experimented with a medium power red CW laser and didn't poke our eyes out like my mother was always yammering about years before. With a little common sense and a pair of goggles you won't either. Too bad we never thought of modulating it, we could shoot a beam down the block and light up cars' tail lights. Alternating turn signals at the stop sign sure confused the hell out of the guy behind.

[AG3Y]

This thing I have is a genuine gas tube laser and has several KV feeding it through a voltage multiplying power supply. I've always thought I could use a impedance step-up transformer to provide the modulating voltage, but it would have to have a tremendous turns ratio to give any serious percentage of modulation. Then I've considered shining the beam through some sort of intensity varying shutter system, but the mechanical details would be tricky to work out. Maybe a mirror attached to a speaker voice coil to vary the aim of the beam?

Lots of ideas, but the most attractive would be directly modulating the DC bias of the tube. However, that's also the most hazardous, considering the voltages involved. Certainly not for the faint of heart to experiment with !

This might be worth hijacking the thread for ! http://www.qrz.com/iB_html/non-cgi/emoticons/smile.gif

73, Jim

[VK2TIL]

Amateurs are exploring this technique;

http://www.bluehaze.com.au/modlight/index.htm

There are commercial units now;

http://www.arborsci.com/detail.aspx?ID=328

The first voice modulation of a laser is said to have been in 1960 I think.

[ka5s]

Quote[/b] (VE7NOT @ June 18 2006,22:24)]Read QST magazines from time to time and kept on with a lasre cw and am transciever. That's right red light laser.

I know some do this.

This is of course unregulated area.... for now.
Lasers are regulated by the FDA, which defines several classes. (http://www.nswc.navy.mil/wwwDL/G/LASER/faq-tech.htm#classes)

I've seen 200 watt CO2 IR lasers for sale at the Dallas Flea Market; just add a vacuum pump, clean CO2, and a high-power 40 MHz source. These are a class 4 laser which requires considerable care to avoid inflicting injury and causing damage to property. You could use them for Moonbounce, I guess. Here, the FAA also gets involved: Outdoor use (http://www.faa.gov/atpubs/AIR/chapter_29.htm)

It doesn't take to much to upset vision, and after several less or more innocent incidents, several states, as well as the Federal (http://thomas.loc.gov/cgi-bin/cpquery/?&dbname=cp109&sid=cp109lijdp&refer=&r_n=hr250.109&item=&sel=TOC_2689&) government, have made it a felony to aim even a laser pointer at an aircraft, or into its flightpath.



Cortland
KA5S

[ac3p]

I once used a light bulb as a dummy load for a 6 meter transmitter. I actually worked a fellow 15 miles away while running 50 Watts to the light bulb in my basement.

I don't think the other station was using a light bulb as a receiving antenna. http://www.qrz.com/iB_html/non-cgi/emoticons/biggrin.gif

[kf6rdn]

Instead of modulating the beam inself, you could use the DLP projection TV theory and modulate a reflecting material. Some kind of LCD-ish type thing.

[kb3mng]

Quote[/b] (AG3Y @ June 19 2006,20:57)]Then I've considered shining the beam through some sort of intensity varying shutter system, but the mechanical details would be tricky to work out. Maybe a mirror attached to a speaker voice coil to vary the aim of the beam?
Alexander Graham Bell used a very thin mirror in the photophone. The mirror would alternate between convex and concave as it vibrated. The incident light (sunlight in Bell's device) would be dispersed by the convex mirror, so less light would fall on the detector. When the mirror was more flat, the light was less dispersed.

[VE7NOT]

Communicating via a penlight laser-beam is the sort of thing I find fascinating cw not as much since some can 'read morse' by light but a laser beam can be am voice. it wouldn't be bad to be on tow peaks in say CO and boost a 200 miles contact via tetra hertz http://www.qrz.com/iB_html/non-cgi/emoticons/biggrin.gif

[ka5s]

Quote[/b] (VE7NOT @ June 21 2006,01:52)]it wouldn't be bad to be on tow peaks in say CO and boost a 200 miles contact via tetra hertz http://www.qrz.com/iB_html/non-cgi/emoticons/biggrin.gif
NEON tetra?

http://www.aquahobby.com/img/neon2.jpg



Cortland
KA5S

[WA2ZDY]

Quote[/b] (ka5s @ June 21 2006,07:16)]Quote[/b] (VE7NOT @ June 21 2006,01:52)]it wouldn't be bad to be on tow peaks in say CO and boost a 200 miles contact via tetra hertz #:D
NEON tetra?

http://www.aquahobby.com/img/neon2.jpg
This is sounding fishy to me . . .

I have an infrared transmitter and receiver here from a garage door opener. My seven year old son and I are going to experiment with modulating the infrared and see if we can demodulate it at the other end.

Should be fun and educational, especially if it works.

I figure on putting an 8 ohm to 1k ohm audio transformer on the output of a tape player or something with the 1k winding in series with the B+ to the transmitter. That should AM it ok. And I'll use something similar for detection at the other end. I can't see a reason why it won't work. Anyone else done this and have ideas?

[kb3mng]

Quote[/b] (WA2ZDY @ June 21 2006,06:39)]I figure on putting an 8 ohm to 1k ohm audio transformer on the output of a tape player or something with the 1k winding in series with the B+ to the transmitter. That should AM it ok. And I'll use something similar for detection at the other end. I can't see a reason why it won't work. Anyone else done this and have ideas?
I can't speak for your particular device, but in general...

Most IR remote controls modulate the IR beam at around 35 - 40 khz, then switch the beam on and off to transmit a stream of bits. The bit stream often starts with a manufacturer code and then has a few bits describing which button was pressed.

The receiver typically has a bandpass filter that matches the oscillator in the transmitter. This helps filter out background noise like sunlight (DC) and incandescent light bulbs (60 Hz, very bright in IR). After the bandpass filter, the computer looks for digital signals that it recognizes.

If you have a scope, I suggest you get in to the receiver and look at the incoming signal before you modify the transmitter. It may give you some insight into how both units work.

Another possibility is to look at it as a source of parts. If the IR LED in the transmitter is a separate device, anything you can do to put a varying current through it will send AM. The necessary current depends on the device; most LEDs I've seen want something between 10 to 50 mA. If it gets hot, it's too much. http://www.qrz.com/iB_html/non-cgi/emoticons/smile.gif

Sometimes the internals are highly integrated. e.g. The receiver may have a single package that contains a phototransistor, amplifier, bandpass filter, and quantizer all in a 3 pin package - power, ground, and digital output. If that turns out to be the case, you might rather just buy some LEDs and phototransistors. They're so cheap that the biggest problem is finding enough other goodies to buy to justify the shipping costs. Or just use it for CW, though that loses some coolness factor. (We already know that pressing the button makes the door open, so finding that the receiver knows you pressed the button is not very impressive.)

So basically, I don't see why your idea wouldn't work if you can inject the signal at the right place in the transmitter and extract it at the right place in the receiver. Choosing the "right place" may be a bit of a challenge, depending on the actual device you are using.

[WA2ZDY]

Thank you for that info Mark, but that's not what I'm using. I'm using the set of IR devices that watch the path of the door for obstructions. It's just one sending a beam and the other detecting that it's there or not. Hopefully this will be easy. It's the kind of thing hopefully my seven year old can grasp.

And if not, then we'll get drastic with some heavy iron and plate modulated RF!