OscilloPhone: Use your Smartphone as an Oscilloscope / Signal Generator
by Loann BOUDIN | 2015
Oscilloscopes and Signal Generators are two essential electronics devices to create and test electronic circuits. Unfortunately, these devices are very expensives for students starting electronics, or makers who want use electronic circuits in their creations just once...
The idea of my project is to rethink your smartphone as a portable, powerful and secured platform, able to simulate an oscilloscope and a signal generator for your electronic circuits. Here, your phone isn't just an accessorize or an ordinairy remote control : it becomes the center of the project, and a tool to help you create better things in the future.
The OscilloPhone project includes:
When writing this tutorial, I wanted to provide excellent quality pictures to facilitate the making of my project. I retouched some photos to get a pure white background (see step 2) using the recent Antzy Carmasaic's Instructable: "Pure White Background Photography Using Smartphone"
Those devices are very important for an engineer on the go or any maker who wants to build electronic circuits. They are the only way to test that your electronic circuit operates as well as you want with electronic signals.
The Signal Generator :
"Signal generators, also known variously as function generators or waveform generators, are electronic devices that generate repeating or non-repeating electronic signals. They are generally used in designing, testing, troubleshooting and repairing electronic or electroacoustic devices." - definition of signal generator by Wikipedia
As the Wikipedia definition says, a signal generator is used to generate various electronic signals into electronic devices.
On the Signal Generator, you can choose the kind of signal you want (sine wave is the most common waveform but sawtooth, square and triangular waves are commonly available), his amplitude in volts or percent, and his frequency.
The Oscilloscope :
"An oscilloscope, previously called an oscillograph, is a type of electronic test instrument that allows observation of constantly varying signal voltages. Oscilloscopes are used to observe the change of an electrical signalled time." - definition of oscilloscope by Wikipedia
More famous than the signal generator, the oscilloscope can in effect allows observation of electrical signals over time. It's a kind of voltmeter for varying and non-varying signals with a screen for the visualization. On the oscilloscope screen, you can observe the form, the amplitude and the frequency of the signal studied.
How to use these devices :
Now that we know what these devices are and what they can do, how to use them?
Instead to try to explain this with a long and boring paragraph, I'll use an example of a circuit that need to be tested.
Let's test the circuit called "non-inverting amplifier" : here, this circuit must amplify twice the input voltage. To check if it operates correctly, a sine wave is generated on the circuit input with the signal generator. Then, the output signal of the circuit is connected to the oscilloscope, measured and displayed on the oscilloscope screen.
If the circuit operates correctly, the output signal shall be sinusoidal and has the same frequency as the input signal generated by the waveform generator. The output signal shall be amplified twice compared to the input.
Conclusion : for testing an electronic circuit, an electronic signal is generated on the circuit input by the signal generator. The output signal of the circuit is measured by the oscilloscope and if it meets the requirements, then the circuit operates correctly.
By this manipulation, we visualize the impact that the electronic circuit has on the input signals.