It is hardly news that you can use your smart phone as a really crummy oscilloscope. You can even use it as an audio frequency signal generator. There are also plenty of projects that allow you to buffer signals going in and out of your phone to make these apps more useful and protect your phone’s circuitry to some degree. What caught our eye with [loboat’s] phone oscilloscope project was its construction.
The enclosure used was an old CD ROM drive (although we imagine any optical drive would have worked). These are dirt cheap and–if your workshop closet looks like ours–probably free. The resulting build wouldn’t win any beauty contests, but for a piece of homebrew test gear it looked pretty good and required minimal effort.
The circuit and phone apps are pretty run of the mill. We’ve covered cell phone scopes before. There’s even one that uses Bluetooth. However, with the availability of inexpensive digital scopes pushing down the price of used analog scopes, you should really have a real scope. As [David Jones] points out in the video below, you should be able to buy a very serviceable old scope for about $50. Skip two weeks’ worth of Starbucks, and you are in business.