IR Remote

hardware

This was a project from EE230, a second year circuits class focusing on amplifiers and filters. The premise of this project was to wirelessly transmit and receive two different frequencies.

The transmitter consisted of a button, switch, 555 timer, 2N2222 NPN BJT, IR LED, and various passive components.

The button was used to power the circuit, on while pressed, off while not. The switch determined which frequency was transmitted (1kHz and 10kHz) by switching between two resistors that controlled the frequency of the 555 timer. The BJT amplified the output current in order to make the LED brighter.

The receiver consisted of a IR photodiode, amplifier, band-pass filters, and output LEDs

The output of the photodiode of the receiver was amplified then sent to two nearly identical circuits, one with a band-pass filter (BPF) focused on 1kHz - this consisted of a low-pass filter (LPF) followed by a high-pass filter (HPF) then by a buffer, and one with a BPF focused at 10kHz. The output of the buffers were then sent to amplifiers to turn on allow enough current to turn on a green or red LED.