EE 230 Design Project
Xin Zhou
Partner: Ruiyu, Chen
Instructor: Santosh Pandey
Introduction:
The project is to build a simple optical signaling device that lights a red LED when one
button is pushed and green LED when another button is pushed. In this project we used many
classical circuits that we learnt in EE230 class. We used oscillator as function generator to
power an IR transmitter. We used photo diode to receive the signal from IR transmitter and
then enlarge the signal by an amplifier, and then, the signal will go through two band pass
filters. Finally the different frequency signal will light up different LED.
Project Design Process:
Oscillator 2
Oscillator 1
Transmitter
Photo Diode
Amplifier
Band pass filter 1
LED 1
Band pass filter 2
LED 2
Results and Discussion:
1. Transmitter and Oscillator
Figure 1, Two oscillators and LED transmitter
1st oscillator was 1 Khz, 2nd was 10 KHz, but we only get 7.5 kHz from the 2nd one.
2.
Figure 2 Receiver part RED LED
When the 1kHz oscillator is turned on, so the red LED is lit up.
3.
Figure 3, Yellow LED
When the 10kHz oscillator is turned on, the yellow LED is turned on.
Signal figures and discussion:
Figure 4, 1 KHz Oscillator output
Figure 5, 10 kHz output
Figure 6 Received Signal and 1kHz Bandpass
From above, the yellow one is the received signal from photo diode, the blue one is the output
of 1 Khz band pass filer. It is kind of integrated.
Figure 7, Reiceived and output from 10 KHz Band pass
The received signal is square wave, after it went through 10 KHz bandpass filter, the output is
the signal after integrated.
Figure 8, Received and 1 KHz band pass filterd
Now we switched to 1 KHz oscillator, the received signal is still square wave, but the output
from the 1 kHz wave was after derivative.
Figure 9, Received and 10 KHz filtered
The output from 10 KHz band pass filter is the blue one which was after derivative.
Conclusion:
Our design of the oscillator was working fine, just the 10 KHz was distorted. The receiver was
fine too. However, our design of band pass filtrers were not very good. The distance between the two
breadboards of transmitter and receiver really affects a lot of the quality of filtering. Our bandpass were
the regular pass filters, not active filters. In the future design, we must use salley active filters to get a
shaper band stop, so it would work better.