I, Naveed Ahmed and Umair Mukati are the students at IIEE (Institute of Industrial Electronics Engineering), located in Karachi, Pakistan. We are currently in the 6th semester of this course. The institute is under the affiliation of NEDUET (Nadirshaw Eduljee Dinshaw University of Engineering & Technology), located in Karachi, Pakistan, and it is a one of the department of PCSIR (Pakistan Council of Scientific and Industrial Research). It was founded by the Swiss and Pakistani Government in 1985.
The project “Digital Oscilloscope” Is being submitted as an entry to “OPEN 7400 LOGIC CONTEST”, organized by Dangerous Prototypes. The oscilloscope has a bandwidth of 1KiloHertz. Yet it can just show the signal applied at its terminals, it does not have a facility to measure the voltage level. The voltage can be measured using some other sort of technique.
We adopted to use Circuit Wizard Software to design our schamtic and layout as were in 2nd Semester that time.
It has three controls to tune signal applied to its terminal. First is the voltage scale, a pot used to vary the voltage scale. Second is the voltage level, a pot used to vary the voltage level. Third is the time scale, used to tune the time scale utilizing potentiometer.
To display the signal we used an LED matrix of 17 x 10. It provides us more resolution and a more observable signal. The LED’s light is green in color and 5mm in diameter.
After fabrication and doing a bit of troubleshooting we have been succeeded in our aim. Credit goes to Naveed Ahmed for his skills on troubleshooting and detecting the errors.
We got much appreciation from our teachers after submitting this project. And we hope that at Open 74XX Logic Contest, it’ll be going to mark its position above all the projects, InshaALLAH (if GOD wish to).
II. Usage Guide
Its usage are properly explained in this figure, I hope you are able to understand,
If it’s still not visible you can see its video as the demonstration of this project.
III. Design DESCRIPTION
The LM3914 is a Dot/Bar Display Driver IC, as the name say can be used in two modes Bar mode and Dot mode. In bar graph mode the LEDs glows in a Bar sequence, like a battery level indicator, with respect to the input voltage, while in the Dot mode, the only one LED is lit at a time, indicating the voltage level. In this project LM3914 is used in Dot mode, the dot shifts vertically corresponding to the voltage of the input signals like in any other typical oscilloscope.
As seen in the figure Two 100k pots are also used. One pot is used in series with the input signal, to adjust the amplitude of the signal. The other pot is used as DC level shifting of the signal.
ii. 555 timer:
The 555 timer IC is used in Astable mode, to provide Clock to the decade counters , this clock serves as adjusting the time base of the oscilloscope.
iii. 4017 Decade counter:
Two 4017 decade counters are used to move the ‘DOT’ of the oscilloscope horizontally along the display. The speed of this dot is controlled using the clock from the 555 timer. These two decade counters are cascaded using 4081 (And gate).
iv. Display/LED Matrix :
A 10x17 LED matrix is used as a display of the oscilloscope, the matrix is formed using standard 5mm LEDs. The rows of the matrix are connected to bar graph driver IC and the columns are connected to the decade counters.