This is a relatively easy to make laser communicator which allows
you to talk over a distance using a laser on one end and a solar cell
on the other end, along with a few extra parts. The receiving end
can instead be a photoresistor, photodiode or a number of other things
but I use a solar cell here because it's a larger target to hit.
I also got very fancy in packaging everything up in a nice fashion,
but you can throw it all together in any way that works for you.
You can see a video of it in
action below.
Using the laser communicator.Note the receiver with the
red spot in the distance.
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Closeup of the red spot on the solar cell.
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Transmitting side (left), receiving side (right).
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How to make the laser communicator
Here's the circuit diagram for the laser communicator. Simpler ones can
be made but the sound you get on the receiving side may not be as good.
Laser communicator circuit diagram.
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Parts list (see below for more information):
- amplifier - This can be a commercially made one or
a homemade
one like mine. For this project I changed a bit by adding
a stereo audio jack socket as I talk about below.
- transformer - I used a doorbell transformer available from
places that sell parts for household wiring. An audio transformer
would be ideal. Most any step-up transformer will give some results.
- 2 white LEDs
- Laser - I used a pet toy laser from a dollar store.
- Batteries - These come with the laser.
- On/off switch
The LEDs are there to protect the laser from receiving too much current.
A high enough voltage will result in too much current flowing through
the laser, damaging it. Instead, when the voltage is high enough, the
LEDs will start conducting, causing some of the current to bypass the
laser, protecting it. Note that the LEDs are connected in opposite
ways from each other. One conducts across the circuit in one direction
and the other in the other direction.
You can buy small amplifiers but I had the parts to
make my own.
They're the same amplifiers that I made originally for use with
my crystal radios. The
photo below shows what it looked like before I put it in the box.
Notice that I connected up a female stereo audio jack socket for plugging
a microphone or other input device into, though I used only the common
connection and one of the other two sides since I didn't really have
stereo. I bought my female audio socket from a local electronics store but
you can For the output I just left two wires to be wired up to
things directly since I wouldn't need a speaker in this case.
For the volume control I used an audio, or log, tapered potentiometer/variable
resistor. A normal one will do but audio/log tapered ones make volume
control easier. For more explanation about that see
my page about
making the amplifier and specifically the video on that page.
Homemade amplifier before putting in a box.
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Stereo audio jack sockets (female)
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I used a doorbell transformer from an electronics/hardware store.
A better transformer would be an audio transformer since it's designed
for audio frequencies. Connect the low voltage side to the amplifier's
output and the high voltage side to the LED's and so on as shown
in the above circuit diagram.
The laser is a cheap one from a dollar store and in this case is
a pet toy laser, though you can find the same cheap lasers for
other purposes. It's the same laser
I installed in my TIE fighter and Star Trek Enterprise models.
Doorbell transformer.
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Pet toy laser from a dollar store.
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Here's my video that goes through the steps I used to make this laser
communicator.
How to make the receiver side
The receiver side is very simple. All you need is a longish box,
a solar cell, a capacitor of around 22 nanofarads (0.022 microfarads),
some wiring and an amplifier. Again, I used
my homemade
amplifier for this but you can also buy small amplifiers.
The solar cell is mounted first on a thick piece of cardboard as
shown below. The ends are cut from a longish box and the box is
lowered down onto the thick cardboard with the solar cell facing into
the box and taped in place. I then painted the box black as a
finishing touch.
Also shown below, the solar cell's leads are left hanging out the back.
The 22 nanofarad capacitor is connected to one lead with the other end
of the capacitor connected via a wire to the amplifier. The other lead
is connected to the other side of the amplifier.
Putting box down on the solar cell.
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The connections at the back of the receiver.
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The circuit may be slightly different but you can use a
photoresistor, photodiode or a number of other things instead of
the solar cell. I like the solar cell because it makes for a larger
target. The light from the cheap laser I used spreads out more quickly
than that of a more expensive laser and so even at a 20 foot/6 meter
distance the spot it makes is quite large as you can see from the
photos above. A photoresistor or photodiode is much smaller and
wouldn't capture as much of that light.
The following video shows this laser communicator in action.
