I’m embarking on a project to design a low-cost, battery-powered oscilloscope suitable for basic signal analysis tasks. The goal is to create a portable device that can be used for educational purposes and simple diagnostics.
I’m seeking guidance on the essential features to include in such devices, as well as recommended microcontrollers or ADCs suitable for this application, and the challenges to anticipate during the design and development process.
Hi @aria_11.
I think that to help you on the right path, you would need to specify things a bit more. Do you mean that you want to make something that a student could make themselves? Like this diy-kit:
Or is it more like a multimeter style device like this:
Do you have an intended price range you’re aiming for? Any specific features you want to achieve in terms of sample rate and such?
This kit can sample at 10Khz and costs less than $5. To make something like this, you could likely use the internal ADC of a microcontroller. It looks like that kit is a modified version of this repo, so you can likely learn a lot there if that’s near your target specs. The same guy has a repo for a function generator as well. Just searching github for Oscilloscope designs can get you even further.
Basically, the more advanced features you add, the higher the speed, the larger the memory → the higher the price since you need more and more specialized components
Sampling rate: For reasonably faithful on-screen reconstructions of the signal being measured, the sampling rate for the Analog-to-Digital Converter (ADC) should be at least 10 times the highest frequency (Fmax) of the signals to be measured. If you want to be able to demonstrate why this is so, you might want to make the sampling rate adjustable between Fmax and 10*Fmax.
Monotonicity: the ADC should be monotonic and have no missing steps.
Any front-end signal buffers or amplifiers should have a Unity Gain Frequency (UGF, also known as unity-gain bandwidth) of at least 10x the product of front-end gain and Fmax. This reduces the reduction in gain seen with lower UGF devices.
You’ll probably want adjustable trigger voltage and sufficient storage to be able to store at least one full cycle of the signal. It’s likely that many microcontrollers won’t be fast enough to display high-speed signals in real time.
There are other considerations, but these are the more technical hurdles.