Donald Had a Serious Case of Red Eye

October 24, 2005

Donald liked to wow people with his PowerPoint presentations. So he developed an easy circuit to modulate an audio signal (CD player) and transmit it over a beam of light (using a laser pointer). The receiver is a simple solar cell with a pre-amp transistor circuit connected to the "line-in" of an audio amplifier. The amplitude-modulated beam of light from the laser pointer produces a varying voltage signal that tracks the audio signal. For added gain, Donald also threw in a pre-amp circuit.

For Donald Marzewski's complete instructions on how to build your own inexpensive laser modulator,

click here


Inexpensive Laser Modulator Parts List
Amt Part Description Allied Part #
1 680 ohms Resistor 977-1256
1 200 ohms Resistor 832-0243
1 18 ohms Resistor 296-5526
1 1N4148 Diode 431-0614
1 2N3904 NPN Transistor 431-0406
1 1 muF Capacitor 881-5274
1 100K Resistor 296-5610
1 1.2K Resistor 296-5564
1 2N3904 NPN Transistor 431-0406
2 1 muF Capacitor 881-5274
1 1.5V AA battery 774-0200
1 Phono plug 283-0016
Additional parts required: Laser pointer, solar cell. Note: As with all laser light, please exercise proper caution.

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