Let’s think of the last time you sent data without wires. We’re not talking WiFi here, but plain optical signals. Free-space optical communication, or FSO, is an interesting and easy way to transmit signals through light beams. Forget expensive lasers or commercial-grade equipment; this video by [W1VLF] offers a simple and cheap entry point for anyone with a curiosity for DIY tech. Inspired by a video on weak signal sources for optical experiments, this project uses everyday components like a TV remote-control infrared LED and a photo diode. The goal is simply to establish optical communication across distances for under $10.
The heart of this setup is a basic pulse-width modulator driving the LED. Pair it with a photo diode for reception, and voilà—light beams become data carriers. Add a lens for focus, and you’ll instantly see the dramatic signal gain. LEDs from remote controls are surprisingly effective. For more precision, swap to narrow-beam LEDs or use filtered photo diodes to block ambient noise from sunlight or fluorescent lights. It’s delightfully simple yet endlessly tweakable.
[W1VLF]’s advice: start small, but don’t stop there—enthusiasts have built entire FSO networks to link rural areas! If you’re intrigued, [W1VLF] has more videos to explore. Want to dig deeper into the history of optical communications? We’ve got that! Once you advance, share your tips and thoughts in the comments below to help others get set up.
“One if by Land, and Two if by Sea,” 1775.
Countless other examples of free-space-optical modulated-light-signal communications dating to antiquity.
This is just doing old things with modern, better tools to get better (read: faster or more efficient) results.
Li-Fi has been a thing for years.
Also, if you’re going to communicate your ideas, do the prep work so you’re not fumbling one-handed complaining about tripods.
Gameboy Color could communicate wirelessly via IR and so did Sega IR7000. Quite a number of hand held devices like PDA often had form of wireless communication. I had one that worked with keyboard via IR. The only limitation is line of sight and distance, cheap IR LED on battery powered devices can’t go more than a few feet.
Actually, most of these (and IrDA) were specifically designed with limited range as a goal (mostly to avoid receiving unintended signals from more than a few feet).
The same hardware, if used in a range-maximizing way, can often manage hundreds of feet of range, or even miles with only mild adjustments.
… and that’s ignoring what comes about if you use a 10BASE-2 transceiver to modulate good high-quality LEDs to be heard on good high-quality phototransistors. (early versions of RONJA)
Old laptops used IrDA to communicate with printers and other devices.
Yes, I’m trying really hard to understand how this is anything other than a reimagining of an already existing tech.
I don’t think they’re implying it’s in any way new.
It’s more a “here’s how you can explore this exciting technology”, kind of like how most of the other HaD content isn’t cutting-edge or revolutionary, just now something we can play with at home.
I did a school project based digital free-space communications decades ago. Things have gotten more convenient, and good parts are much cheaper, but nothing fundamentally changed.
My project would have been far easier with such documentation available… but it also probably wouldn’t have been worth the huge contribution to my final grade :)
Li-Fi has been a thing for years.
Also, if you’re going to communicate your ideas, do the prep work so you’re not fumbling one-handed complaining about tripods.
Also if you’re going to communicate your ideas, do the prep work so you’re not duplicating your complaint posts on a site promoting hacks not production prowess.
IR Blasters were a thing. I wish I could remember the name, but a recent YT HiFi channel did a bit on using laser diodes to send PCM audio wirelessly to surround speakers. The paths used mirrors along walls and ceilings to avoid interruptions. Perhaps a tad excessive but if you can’t run wires …
It’s DIY Perks. It’s a great channel, the guy does amazing things.
When I was young I had a little book of simple transistor projects, two of which were a light beam voice transmitter and receiver. These used an incandescent light bulb and selenium photocell for the optical interface. Years later I was reminiscing through my old stuff and wondered why they hadn’t used an LED; I got my answer when I flipped back and saw the copyright date was 1963.
We did that experiment in 5th grade at that time, and increased the range by mounting the lamp and cell at the focal points of a pair of 1 foot diameter parabolic reflectors – we obtained a range of 20 – 30 feet with the setup in 1962
I mean. There a number of universally recognized hand signals to communicate to other drivers your thoughts on their driving habits. Does that count?
Didn’t @DIYPerks recently showcased similar open air laser to send audio signal for a DIY surround system?
It’s a bit different but a have look at project ronja http://ronja.twibright.com/
I was about to write “How about beautiful Ronja project from about two decades ago”
:-)
Nice to see that it is not forgotten.
Not forgotten and I have seen commercial installs between hospitals for transferring records. But it got removed about 8 years ago. There was also a project that used lenses and stabilized bases to transmit free space using off the shelf fiber trancievers.
Vertical Video Syndrome…
phone cams work sideways, too ¯_(ツ)_/¯
I didn’t see a mention of the Alexander Graham Bell Photophone (1880) that used light to send voice communication. However, I do hate to reference a classic source again but in the 60s Radio-TV Experimenter Magazine had an article on building a transceiver for “communication over light beams”. There was a follow up article using infrared as well.
There have been people having some success using slightly modified fiber optic transcievers in FSO setup.
I did this in 1983, 12yrs old, science project, I used an LED connected to radio shack mini speaker output, and used another mini speaker with photo transistor connected to its input. I used a cheap kids telescope, sent music across the school.
Is there any site or video discussing “enthusiasts have built entire FSO networks to link rural areas” as mentioned in the article. The topic is of interest. I work with long range packet radio networks but adding optical links to the mix would be useful. Hopeful there is a site detailing a build and data rates achieved.
There is mention of rural optical networks built, but im having trouble finding any info on such a thing. I do a lot of work with packet radio networks, would like to add optical links to the network. Is there any site or video detailing building such a device or network?
http://ronja.twibright.com/
https://en.wikipedia.org/wiki/RONJA
(and related stuff)
It’s old enough that a lot of it has fallen off the internet, but that’s a good start.
These days, you wouldn’t use exactly the same implementation, but it wouldn’t be all that hard.
Using LEDs and optical focus usually supports much higher bandwidths than lasers (unless they’re purpose-built for high-frequency modulation). It also bypasses most eye-safety issues (and regulatory burdens).
If you’re only interested in limited bandwidth(often 10s of kHz) and need a non-visible beam, you can often make/buy/recycle ir laser diode assemblies. Don’t try to focus them to a point source. Instead, expand the beam as much as possible before re-focusing it, because a 10 cm beam has far longer ange and suffers much less rain/atmospheric interference than a 1 mm beam even though the power density is lower.
It is also much more eye-safe.