AM LIGHTWAVE TRANSMITTER AND RECEIVER BY JOE SCHARF ------------------------------------------------------------------------------- SCHEMATIC 1 [TRANSMITTER] ------------------------------------------------------------------------------- MIC* C1 () + .1 uF |---------(OO)-----|(--------| +9V | () | ^ | R3 R4 | /|\ | 5.6K 5.6K | | *---/\/\/\-------*---/\/\/\--|-------*-------*------| | | | | | | | | >R1 | | | | | |---->>>50K | >R5 >R8 | __|3___|2_ >VAR | >1K >220 | \ + - / |RESIST | > > | \OP AMP/-----|-------- | | *----------------\741 /7 | | | ** | 4 \ / >R2 | C/NPN Q1 | \/ >1M |---------B| TRANSISTOR | |6 > | | E\ 2N2222 | | | C2 | | | | | | + 10 uF | >R6 | | ----------*---|(-----*-->>>50K | | >VAR | | |RESIST| LENS | | __|___*** ^ | | \LED / (|) | | \ / ( | ) | R7> \/ (|) | 1K> -----|---- \/ | > | LENS | | | OPT. | | | | | | |--------------------------------------------*-------| | | -------- ---- -- _______________________________________________________________________________ R1-GAIN CONTROL R6-LED BIAS CONTROL ADJUST R6 FOR BEST SOUND QUALITY R8-LIMITS CURRENT APPLIED TO LED * - MIC- USE CRYSTAL MICROPHONE OR ELECTRET UNIT (CONNECT RED LEAD TO 9V) ** - TRANSISTOR - USE A 2N2222 NPN TRANSISTOR. *** - LED - USE A HIGH-BRIGHTNESS RED OR HIGH POWERED INFRARED LED FOR BEST RESULTS _______________________________________________________________________________ THE 741 AMPLIFIES VOICE SIGNALS FROM THE MICROPHONE AND COUPLES THEM THROUGH C2 TO MODULATOR TRANSISTOR Q1. FOR A FREE-SPACE RANGE OF UP TO 1000 FEET (AT NIGHT), USE A LENS TO COLLIMATE THE LED BEAM OR USE THIS CIRCUIT AS AN OPTICAL FIBER TRANSMITTER. _______________________________________________________________________________ SCHEMATIC 2 --- AM LIGHTWAVE RECEIVER _______________________________________________________________________________ |-----------------------------------------| | | | | | | | | >R1 | >100K | > | LENS | C1 .1uF | ^ *----|(---------*-------| | (|) C| | | | ( | ) /Q1 | | | +9V ( | ) B|PHOTOTRANSISTOR | | | ^ (|) E\ |-----| | | | /|\ \/ | | __|3_|2_ | | | LENS | | 4\ + - /7 | | | *-------*----\ 741/------|-----------------*---------* | \ / | | | | \/6 | | | | | >R2 | ------ C2 | | >100K | ^^ .1 uF | | > | ^ |^ | | | | | | |--------* | | | | | -------- | | | ---- | | 3|\ | - | | |------|+\|6 | | | |* \--------------| | R3< | | /5 C3 | + | 10K<<------| |----|-/| 100uF ----- | VAR< | 2|/4| ^ | RESIST| | | | | | | | 8 OHM|---/| | | | | SPEAKER| || | | | | |---\| | | | | | |------------------------*---------*-------*--------------| | | ---------- ------ -- _______________________________________________________________________________ R2-GAIN CONTROL R3-VOLUME CONTROL C2-PREVENTS OSCILLATION KEEP LEADS TO BATTERY SHORT. * --- OP AMP --- THIS MAY NOT LOOK LIKE AN OP-AMP BUT IT IS (VERY HARD TO DRAW THEM ON THE COMPUTER. USE A 386 OP AMP FOR THIS ONE _______________________________________________________________________________ THIS RECEIVER WORKS BEST IN SUBDUED LIGHT OR AT NIGHT WHEN USED FOR FREE-SPACE COMMUNICATIONS ALWAYS PLACE A SHIELD OVER THE DETECTOR IF SUNLIGHT OR BRIGHT ARTIFICIAL LIGHT IS PRESENT. AN INFRARED FILTER SHOULD BE USED FOR BEST RESULTS (DEVELOPED COLOR FILM WORKS WELL) UNLESS THE TRANSMITER LED EMITS VISIBLE LIGHT. CAUTION : THIS CIRCUIT CAN PRODUCE LOUD SOUNDS. DO NOT PLACE SPEAKER CLOSE TO YOUR EAR. _______________________________________________________________________________ FEEL FREE TO PASS THIS CIRCUIT AROUND AND IF YOU HAVE ANY QUESTIONS OR PROBLEMS YOU CAN CONTACT ME ON CHUCKS PLACE (304)-776-7078 BY LEAVING E-MAIL TO: JOE SCHARF _______________________________________________________________________________