Phone Scope Build Uses Old Optical Drive

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.

13 thoughts on “Phone Scope Build Uses Old Optical Drive

  1. I’ve been using an Android phone as a makeshift audio signal generator; I’m guessing that it’s a class D amp that relies on the 32 ohm load from the headphone. Feeding the headphone output direct to an op-amp with 10k input resistor gave a very distorted waveform, but with 50 ohm resistor it was fine.

  2. Almost zero information about the actual hack/project in the article- in fact, there’s more info (even video) on how to buy a scope, than how he built this one. I come here for articles that inform me on hacks, projects, and home builds. This one’s a fail.

    1. Just to be clear, the hack’s interesting; it’s the article that failed to inform. Worse than that, the writer seems to think that hacking/building your own tools is a foolish idea, insisting we “should” buy them instead. I would be offended if the hack was mine, and I finally got featured on HaD, just to read about how it was a bad idea, and that I should have just bought something instead. The writer has a responsibility to uphold the basic tenets of this website, which is an amazing community that I’m proud to be a part of.

  3. you should be able to buy a very serviceable old scope for about $50.

    But what if I don’t want to? What if it’s not even a matter of cost, but just a thorough consideration of what I would need a scope for and how often? What if I don’t have the room to spare for a bulky scope that I would realistically only use once a month, to debug TTL signals slow enough to see individual blinks on an LED? Not everyone has the room to spare, and at the same time there’s these wonderful versatile and oftentimes quite cheap computers that come in a package that’s not much larger than their screen.

    Also, you carry “hack” in your website’s name. “You should be able to buy x” is — almost by definition — the opposite of a hack.

  4. A good basic project. I might make the circuit to just battery operate and plug up the two things and go. No ground hazard.
    Note the backwards jacks on the adapter. Plus on the left of ground? Standards! Even if it is only AC coupled.

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