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justine aquino (Mnado)
Advanced Member
Username: Mnado

Post Number: 87
Registered: 12-2005
Posted on Friday, January 13, 2006 - 5:46 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

simon what is the IR LED in the free space laser data transmittier for?can you remove it and replace it with a jumper wire instead or does it have a use then the laser pointer to be removed intead?or are they both needed?

pls reply as soon as possible.
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justine aquino (Mnado)
Senior Member
Username: Mnado

Post Number: 109
Registered: 12-2005
Posted on Friday, January 20, 2006 - 6:35 am:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

or is it IR i think it is any way i have new updates you can put the laser itself to the place where the indicator(LED)is placed any way laser is a kind of diode too and instead of a laser i used and IR LED it works but doesn't perform good enough cause i can't get it send signals farther like one from remotes i don't know why placed capacitors and all i can find in the remote available in my house. ..too baaaaad...
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Simon Quellen Field (Sfield)
Senior Member
Username: Sfield

Post Number: 940
Registered: 12-2004
Posted on Friday, January 20, 2006 - 10:44 am:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

Slow down.
There is a concept called a "sentence".
It makes it easier to understand what you are trying to say.
Short sentences are good.

The diode I used is a clear lensed red LED.
It is red.
It is not infrared.

The signal from the serial port switches between +12 volts and -12 volts.
We need it to switch between +12 volts and 0 volts.
So we put in a diode that blocks negative voltage swings.

It could be just about any diode.
I chose an LED because I have a bunch lying around.
It is also handy to have a device that lights up to tell you it is working.

Some serial ports have enough current to make the laser light up.
You can connect the laser directly to the port if that is the case.
This is what you have done.
However, now instead of lighting up for the dots and dashes,
it lights up for the spaces in between them, and is dark for the dots and dashes.

A laser has several advantages over an infrared LED.
It is brighter, so the signal goes farther.
It is focused, so the signal goes farther.
It is visible, so you can aim the tiny little dot at the tiny little receiver
from a mile away.
It goes a mile instead of 30 feet.

Adding capacitors at random to a circuit is unlikely to do anything good.
The reason the remote control goes 30 feet is because the receiver is very
sensitive and has circuitry for tuning out other noise.
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justine aquino (Mnado)
Senior Member
Username: Mnado

Post Number: 111
Registered: 12-2005
Posted on Friday, January 20, 2006 - 6:08 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

yes.thank you i have misread the article,and about that free space laser data transmitter i changed the serial port connector to an earphone jack,and can send music,but the problem is it goes very loud on the "beats" like the drum,its heard almost 70 percent of the music and the singer and other musical compenents is not heard clearly,..i experimented with big and small photocapacitors,i also tried filtering it by putting papers infront but no good results,..so its not good to put the laser diode to the LED's place?and what are the advantages of IR LED?
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Simon Quellen Field (Sfield)
Senior Member
Username: Sfield

Post Number: 943
Registered: 12-2004
Posted on Friday, January 20, 2006 - 6:36 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

You keep saying photocapacitors.
I think you mean photocells, solar cells, phototransistors, or photoresistors.

The circuit used for sending data uses the transistor as a switch.
It is either on or off.
That is why you are hearing the loud noises and not the soft ones.

What you want is a linear amplifier, where the transistor base is biased
into the linear region. But if you want to send music, just use the
simple laser communicator.
It already does voice and music just fine, and it is even easier to build.
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justine aquino (Mnado)
Senior Member
Username: Mnado

Post Number: 113
Registered: 12-2005
Posted on Saturday, January 21, 2006 - 6:45 am:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

sorry about the photocapacitor word,...anyway i got this big 'ol junk from the basement,its an old whatever that is my dad own uhh it is like a black cd with all the scraped part well its not cd i just don't know what its called,.about that "CD" player i found some very good components like a darlington ic,and a double sized transformer(the one needed in the simple laser data transmitter)and my savings,i think its not in use by now its dated 1899 i found 20 coins inside(i don't know why its placed there)i know it would work but it needs more power supply 6 volts,perhaps?and i used an electret micro phone (small one)as the voice input and i experimented with a bass blaster (a bit small,commonly used in speakers), and works better than amplified light from a radio but the voice is kind of blurred in a way like,....try covvering your mouth then talk it kinda sound like that but a bit clearly,and i also used a thick nylon string 3mm(above)and i connected it to the point of the laser then to the photocell of the receiver and then connected to an ear phone(i don't like earphones much ,so i connect it to a computer instead and let the computer hear the sound for me...)and its better but doesn't reach much distance so if the transistor is used as a switch can i be used as a replace ment for the oscillator?

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