IRLink

Status: Completed
Dates: April 2007

Overview

In the Analog Circuits and Systems course I took at Calvin College I was required to complete a design project. The goal of the project was to apply some of the knowledge I had acquired throughout the course into a real world prototype. The class formed teams of three and we quickly came up with an idea for our project, the IRLink.

The IRLink is an analog transmitter and receiver pair that is designed to transmit line level analog audio signals over short distances using infrared light. The transmitter is designed around a bipolar junction transistor (BJT) driving an array of infrared LEDs. The receiver includes an infrared receiver, op-amp gain stage, and op-amp based 120 Hz filter. The final prototype also included a small converging lens on the receiver to increase the range of the wireless link. Given the design time frame, the device worked reasonably well. With the addition of the converging lens, the device had an effective range over 10 feet.

Schematics

IRLink Transmitter Schematic

IRLink Receiver Schematic (Click image to view full size)

Bill Of Materials

Q1, NPN BJT Transistor, 2N2222
U1, U2, U3, Op-Amp, LM741
D1-7, infrared LED, Fairchild QED234
IR receiver, Lite-On LTR-301
capacitors and resistors as marked