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Chris
Posted on Monday, March 24, 2003 - 4:32 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

I am wondering if I can use a 1200 ohm/8 ohm audio transformer for the transmitter or will that be too big for is to work? I am lacking a credit otherwise I would order the correct transformer from your site and Radioshack Canada does not carry the part number listed in the instructions. Also, if I want to plug speakers into the receiver instead of an earplug, do they need to be powered? Thank you for your help.
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Simon Quellen Field (Sfield)
Posted on Monday, March 24, 2003 - 5:38 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

I would expect your transformer to work, but I haven't tried it.

The light falling on a solar cell does not generate enough power
to operate a standard speaker. You need either a high impedance
earphone, such as the one in our catalog, or an amplifier.

Powered speakers may work, but they usually don't amplify much.
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Drew
Unregistered guest
Posted on Saturday, February 26, 2005 - 11:41 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

At the buck-or-two you can buy little $2 "spy ears" I believe that if you place the solar cell in place of the mic, and a speaker where the headphones go, they should work.
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mattb
Unregistered guest
Posted From: 63.17.125.61
Posted on Saturday, September 17, 2005 - 10:49 am:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

is there a way to send not just words but images and programs? Would it be the same basic thing or would i need to tweek the comunicater a lot. any info owuld be great.
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Nikola Dulgiarov (Nikola)
Member
Username: Nikola

Post Number: 16
Registered: 8-2005
Posted on Saturday, August 19, 2006 - 5:55 am:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

I guess you could use binary code to encrypt and decode a picture .You might be able to use some kind of computer program that could encrypt a picture and the computer's com port conected to the transmitter.
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David Joseph (Aeronix)
New member
Username: Aeronix

Post Number: 1
Registered: 12-2007
Posted on Monday, December 17, 2007 - 12:59 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

I have been trying to build the laser communicator with one modification: namely, using a phone jack instead of the microphone and earphone jacks. Then I used a microphone or an audio cable hooked to a radio to send the information. To receive the info, we managed the same type of connection using a solar cell and an amplifier with the phone jack in between. Since we didn't get anything we soldered a piezoelectric ear to a solar plate as in the project description. Still nothing. Does the phone jack (Radio Shack part #274-249) make a significant difference, or should we look for something else? Thank you.
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Simon Quellen Field (Sfield)
Senior Member
Username: Sfield

Post Number: 1814
Registered: 12-2004
Posted on Monday, December 17, 2007 - 1:49 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

It sounds like you aren't modulating the signal enough.
When you are modulating well, you can see the laser beam
get brighter and dimmer as the signal changes.

If your radio is not designed to drive an 8 ohm earphone,
try reversing the transformer. That will give you better
modulation, at the expense of some range reduction.
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Ian (Elec)
New member
Username: Elec

Post Number: 1
Registered: 11-2008
Posted on Monday, November 3, 2008 - 3:12 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

i have been working on the laser transmitter for over a week and can't figure out what is wrong! I even got the kit and still cant get it to work!
Please Reply

Thanks
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Theresa Simmons (Theresa)
Advanced Member
Username: Theresa

Post Number: 74
Registered: 1-2008
Posted on Monday, November 3, 2008 - 3:43 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

We'll need a little more information in order to help you.

Does the laser light up?
Can you see the brightness vary as the sound level changes?
When you hold the receiver up to a fluorescent light bulb or
a television, can you hear a buzzing sound?
When you wave your fingers in the light beam, do you hear clicks
and pops in the receiver?
What are you using as a signal source? Is it designed to drive
an 8 ohm earphone?
Are you using the piezoelectric earphone and solar cell for the receiver?
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Ian (Elec)
New member
Username: Elec

Post Number: 2
Registered: 11-2008
Posted on Monday, November 3, 2008 - 4:07 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

The laser lights up
i canno't see the light level changes
no pops or clicks
i am using the kits pieces.
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Ian (Elec)
New member
Username: Elec

Post Number: 3
Registered: 11-2008
Posted on Monday, November 3, 2008 - 4:10 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

I do not hear a buzzing sound, and i am using a wind up radio,
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Simon Quellen Field (Sfield)
Senior Member
Username: Sfield

Post Number: 1921
Registered: 12-2004
Posted on Monday, November 3, 2008 - 7:24 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

First of all, let's get your receiver working.
You aren't hearing any sound coming from lights that flicker
at audio frequencies (fluorescent lights and televisions).

If your connections to the solar cell are good (you can check them
with a voltmeter -- you should get about a half a volt when you
hold the cell up to the light), then your problem might be the
piezoelectric earphone. These devices can become polarized by
static electricity from your fingers when you handle the leads.
To fix this, simply drop the earphone onto the table from a height
of about a foot. This will set up oscillations in the piezoelectric
material that will cancel the polarization.

You can check the earphone by putting it in your ear and touching
the leads to each other. If you hear clicks, it is working. If you
don't, try dropping it and trying again.

When you have a working receiver, try it with the laser again.
Turn up the volume on the radio and see if you can hear anything, or
see the brightness change in the laser.

Your wind-up radio may not be designed to drive an 8 ohm earphone.
If it is designed for a 16 ohm or 32 ohm earphone, it might not be
strong enough to modulate the laser. Try a different radio, or try
reversing the transformer, so that the 1,000 ohm side is connected
to the radio, and the 8 ohm side is connected to the laser.
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Ian (Elec)
Junior Member
Username: Elec

Post Number: 4
Registered: 11-2008
Posted on Monday, November 3, 2008 - 9:27 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

I did what you said to do and it worked, but only to some extent i hooked it up and pluged it in, and i can sort of hear the music through all of the crackeling, and it is almost undecipherable.

P.S i had to put the plug that goes into the radio 1/2 to 2/3 of the way in to make it produce a sound.
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Gary P (Phantom_menace)
New member
Username: Phantom_menace

Post Number: 3
Registered: 7-2008
Posted on Tuesday, November 4, 2008 - 1:34 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

You might need to switch to a different type of cable (stereo or mono) than the one you are using now in order to get it to work completely plugged in.

Also, sometimes the connectors inside the jack become bent through ordinary use or if the radio has fallen with a cable or earphones plugged in.
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Theresa Simmons (Theresa)
Advanced Member
Username: Theresa

Post Number: 75
Registered: 1-2008
Posted on Tuesday, November 4, 2008 - 2:49 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

It sounds like you should try a different signal source.
Try a different radio, or a tape recorder, or a stereo.

You also should check the earphone for whatever device you use,
and make sure that your plug matches the plug on the earphone.

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