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Laser Listening Schematic

This device is designed to allow a person to hear sound from within rooms, while being outside the room. It involves pointing a laser at a window or similar item and receiving the vibrational information using the laser.

Parts list

All resistors are 1/4 watt, 5% unless otherwise noted.

R1-2200 ohms
R2-220 ohms
R3-33000 ohms
R4-10 ohms
R5-10,000 ohms, miniature potentiometer with SPST switch
R6,R7-22,000 ohms
R8-25000 ohms, trimmer potentiometer

Capacitors

C1, C6, C9, C10-330 uF, 16 volts, electrolytic
C2, C4-10 uF, 16V volts, electrolytic
C3-0.001 uF, 50 volts, ceramic disc
C5-0.68 uF, 16 volts, Tantalum
C7, C8-0.047 uF, 50 volts, ceramic disc
C11-4.7 uF, 16 volts, electrolytic
C12-1000 uF, 16 volts, electrolytic

Semiconductors

IC1-SK3891
IC2-LM380
IC3-741
Q1-TIL414, NPN phototransistor (Radio Shack 276-145 or equal)
Dl, D2-SK-3090 germanium diode, or equivalent

Other components

B1-9-volt transistor-radio type battery
J1-miniature phone jack
Ml-250 uA meter, panel mounting
S1-SPST switch, part of R5

Miscellaneous

Cabinet, Pre-drilled PC board, brass sheet and tubing, wire, solder, etc.

The following is available from Dirijo Corp., Box 212, Lowell, NC 28098. A drilled prototype-board with a component layout overlay in place, model LXVR-1.



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