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LED at a certain Frequency

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priestinacloset

New Member
Hello I wanted to build an LED flasher but at a certain frequency.

I used wavelength*freq=c to determine that a light whose max wavelength was 940nm could have a max frequency of 3.19 * 10^14 hertz. My goal was to get a frequency in the 2 Ghz range. I thought i would need to use a 555 timer configured as a multivibrator but I am not certain and was looking for some guidance. Any help would be greatly appreciated.

thanks
 

MikeMl

Well-Known Member
Most Helpful Member
Let me get this staight? You want a 555 to flash a Led On/Off at 2 Ghz??????

Max operating frequency for the 555 is ~1MHz. A normal led can be modulated a few MHz.
 
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Sceadwian

Banned
You can't flash an LED at 2GHZ, due to the amount of time it takes an LED to turn on and off it has a much more limited frequency. In order to operate an LED at 2ghz it would have to be physically so small that you wouldn't be able to visually detect it's output.
 

audioguru

Well-Known Member
Most Helpful Member
But the school teacher does not know the limitations.
Why are there teachers that do not know about what they are teaching??
 

tcmtech

Banned
Most Helpful Member
Nope. A few tens to hundreds of hertz typically.
RF communications however often use multi GHZ frequencies.

I think that some fiber optic communications systems may be using single LED sources that may be modulated in the few hundred MHZ range though.
However I could be misinformed about that though.
 

Sceadwian

Banned
The IRDA is currently developing IRsimple, the end goal being 100mbits, they've demonstrated 16mbit data rates over IR. I'm sure they use a modern bit encoding method, but worst case scenario even if they used Manchester encoding that would be a maximum modulation rate of 200mhz, and that's pushing the limits.
 
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