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Topic: How can I communicate wirelessly without IR? (Read 3452 times) previous topic - next topic

TECH GEEK

How can I communicate wirelessly without IR?
I'm hoping to use radio waves created via a 555 timer circuit on a breadboard, to send a variable frequency to be sensed via an antenna on my Arduino Mega 1280...
But i'm unsure how to create a radio transceiver & receiver using common components, no IC's besides 555's and other very common IC's....
also I don't even know how an radio antenna system works.
(I DO know how an IR remote communicates with a TV, and I assume radios work on similar principles? Right?)

can anyone help me with these circuits?
As always... Thanks for posting!!!

CrossRoads

You an use RF instead.

Principles are not really the same. IR is just light turning off & on, just at a wavelength you can't see. The receiver sees flashes of light, and  outputs a high/low signal accordingly. 

RF has to transmit  a burst of radio waves that the digital signal is encoded onto. The receiver has to sync up to the carrier frequency, and extract the digital info from it.
You can buy an RF TX & Rx pair for <$10 with 17cm piece of wirewrap wire for an antenna, you will not be able to duplicate that performance with 555 timers.

Need to find comparable versions of these:
http://www.sparkfun.com/products/8950
http://www.sparkfun.com/products/8946

Maybe these
http://www.laipac.com/easy_434a_eng.htm
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

compuslave

In many ways the two are the same, though. They are both forms of electromagnetic radiation, just at different wavelengths. They are both digital signals, ie ons and offs. The rf is just more of a moving target since it's carrier frequency can vary. Its a trip to think about how all of our devices, our phones and wifi equipped laptops and all that stuff is spewing out this radiation all the time and its exactly like the light we see, just at a different wavelength. I often imagine how bright a cell phone tower must look if I could see that wavelength of 'light'.

My head just exploded. I should probably clean up this mess.

Oh, nevermind, one kleenex got it.

CrossRoads

Sure the same, but operationally very different.
For IR, you just send current at low switching frequency thru an LED, and receive it with simple phototransistor. Operation is limited to line of sight (or bouncing off a wall or ceiling sometimes). Can even get your ipod to send the IR, its pretty slow.
For RF, you replace the LED & phototransistor with complete modules that must end up sync'ed or you don't get meaningful data out. And it will work 100m away - IR can't do that.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

TECH GEEK

Yes I could just buy some pre-made device that takes care of the building and most of the testing...
But what fun would there be in that???
Not to be rude, but the reason I want to use the "555+commonParts+ Breadboard" approach is for the challenge of that method...
But if it is not plausible to use this approach, then how am I ever going to learn about electronics?

ps: if i seem to be rude above, which i'm trying not to be, it may just be that it's 3:00AM and I can't get to sleep at all tonight...
As always... Thanks for posting!!!

Grumpy_Mike

It is not legal to make your own transmitters unless you are licences to do so. Your best bet is to get yourself a ham licence, that is how you learn but not before you have to prove you know the fundamentals of what you are doing.

TECH GEEK

As always... Thanks for posting!!!

CrossRoads

Ok, I googled 555 AM transmitter and got quite a few hits,
here's one example
http://www.youtube.com/watch?v=gASzqSyHzyM

so transmitting seems doable.
Here's a receiver also
http://m8051.blogspot.com/2011/02/am-radio-receiver-using-555-simple-rf.html

Do some searching on 555 design contest and see what you can come up with.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

Grumpy_Mike

Yes but it is still not legal.
@TECH GEEK What country are you in?

CrossRoads

I would think transmission power & frequency would be a factor in that Mike.
In the US there are bands where low power transmissions are allowed.
http://en.wikipedia.org/wiki/Low-power_broadcasting

Not many, but AM looks like one of them if this data is correct.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

Grumpy_Mike

Quote
In the US there are bands where low power transmissions are allowed.

Yes but in the UK and many other countries there are no such allowances and any form of RF transmission on a home built set is legal no matter what the power and frequency.
Especially once you start modulating such a transmitter you have the capacity to cause interference over a wide band, not just the frequency you are using.

compuslave

Nice link, CrossRoads!

I didn't mean to imply that ir and rf were functionally the same. I only went off on a tangent because this thread got me thinking about all the invisible light around us.

:headexplodes:

TECH GEEK

Back...

Yes  live in the USA, State = PA...

also I  agree with crossroad about the power of the transmission. If my professional grade Remote Control (R/C) truck can't be controlled farther than 500 feet, than I assume that Video crossroads provided should be OK?  Also I have seen hundreds of educational NPN-based radio station kits sold where I live...
As always... Thanks for posting!!!

CrossRoads

As long as you're no stronger than baby monitor power and not on a frequency that's bothering anyone, you'd probably be okay.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

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