Cute Oscilloscope Uses LEDs For Display

Oscilloscopes were once commonly called CROs, for the fact that they relied on cathode ray tubes for display. Since then, technology has moved quickly, and oscilloscopes these days almost entirely rely on modern screens like LCDs. However, [lonesoulsurfer] went a different route with this fun DIY build, creating an oscilloscope with a low-resolution LED display.

Yes, the signals are shown on a 10×10 matrix made up of red LEDs. The individual pixels look nicely diffused and chunky thanks to the fact that [lonesoulsurfer] was able to source square 5mm LEDs for the build. The whole project only uses four ICs – a decade counter and a LM3914 LED driver to run the display, a 555 timer for clock input, and an LM386 op-amp for amplifying incoming signals.

With a mic fitted onboard, the oscilloscope can act as a simple music visualizer, or be used with a probe to investigate actual circuits. It may not be of great enough resolution or precision for fine work, but it’ll at least tell you if your microcontroller’s clock is running properly if you’re scratching your head about the function of a simple project.

We’ve seen some great DIY oscilloscopes over the years, like this neat Arduino-based build. Video after the break.

29 thoughts on “Cute Oscilloscope Uses LEDs For Display

  1. This looks amazingly like the one in R-E in the mid-1980’s. Much cleaner, though. Not too hard to add a zero crossing detector to either trigger the reset on the ’17 or fudge the ‘555 pin 5 for freq pull.

  2. There were projects like this in the seventies, as LEDs got cheap enough. And after barcode drivers were out. Yes, likely a 4017, since you needed the encoded outputs, and there wasn’t much choice if you wanted CMOS.

    Back then, scopes weren’t common among hobbyists, so the idea was enticing. But not much density, so not much for displaying waveforms. And not much speed.

    Forest Mims definitely had one like this, but there were others.

      1. I mean what I said.

        And what scooes were available cheap had limited bandwidth, were not DC coupled, and didn’t have triggered sweep.

        About 1975, Heathkit started to have better scopes at lower prices, but they were still not “cheap”.

        There were some scope projects around that time that actuallyhad DC clupled amplifiers, and triggered sweep. Not great bandwidth though.

        So when this sort of thing came along, it was interesting because it was simple and sort of seemed like getting something you didn’t have. But other than a neat thing, nobody talked about using them.

        MITS had some sort of scope project, but as I recall it didn’t have an XY grid. Just a string of LEDs, with triggering, so useful only for digital signals.

          1. And a sense of adventure as plenty of those components are not only clones (aka. fake) but also do not come close to the specs of the original.
            Beyond C’s and R’s it is seldom easy to confirm that the thing in your hands is effectively what you expect it to be. Makes me order ‘expensive’ at the big distributors again, and even then I do not have all the guarantees I’d like.

      1. Only for citizens and non businesses. The rest and international shippers still enjoy subsidized cheaper shipping. It is great to get something from Hong Kong in 6 days but somehow it takes 8 days and 5 times the cost to ship something three states away. I have little sympathy for the USPS as it keeps shafting the very citizens that subsidize it for its oligarch overlords and even then manages to cock that up. When someone can literally order the same item from China instead of a town in the same state for cheaper shipping (and faster), then there is a problem imho. Make Amazon just do all of its own logistics and have a business class and a private class. All mail delivered by 1pm so business and people have time to react that day instead of getting it at 630pm and waiting until the next day to get a fix in order. In response to increased failures, they manage to just shuffle local parcels in a 4 day holding pattern until it lands by purposely shuffling around current routes and logistics so it is just logs floating in a jam gently pushed along by the log behind them. And if you have ever had to deal with a lost or broken item then you probably know all they tell you to do is produce bar-level proof through a buggy online portal or just pound sand. It is sh%t for lack of a better term and there is no alternate route. Most local POs don’t even handle it anymore, pointing your grandma to their QR code so she wont download the app on her jitterbug and get money back or the site input times out in 5 mins for uncommon entries like tracking numbers and complete addresses and problem descriptions. Late by a month? F you. We lost your dad’s insured medical device and messed up an entire year of PT? F you. Medical bill that I can steal so it goes into collections even tho it was sent certified? F you. Fell in a post office on a wet floor and broke your head open? F you. Item is lost and I waited the amount of time the website said before filing but it is telling me it is somehow late? F you. These and many more problems with the USPS give me little respect for the people in charge and the crappy local carriers that ruin it for the good ones. I just need to move to England I guess lolol. Oh well.

        1. Sorry, this project is fun though :) This brings back happy memories of a kit I saw in an ad and always wanted but never followed up on in adulthood. Sounds like a fun weekend project :) I got all ranty at usps lol and forgot the very reason I was here. Not ranting at you either just venting I guess as I wait for parts that are somehow two weeks late coming from TX like it is in Canada lol. Constant issue.

    1. When he was in high school, there were no LEDs. He had to finagle one for his seeing eye gadget, they weren’t yet available. I think he was out of high school by then.

    2. Yes, that would be basically the same circuit, just tuned down for fewer LEDs. I did wonder why this project used a 10×10 matrix when I saw the picture at the top, but ten outputs from a 4017, and ten outputs from the 3914 bar-graph chip sets the size. These days it’s not too hard to get an 8×8 matrix out of a kids toy in a thrift store, but those big square LEDs look better.

      I like it.

  3. Funny coincidence, just yesterday when clearing some old hardware, I took my old version apart – the same components,
    based on an article in Elektor, probably 30 to 40 years ago, using LED strips 10 long, so high density.
    Burkhard Kainka used a simpler approach in his book about the microbit – there 5 x 5 LEDs were enough and no extra hardware – just a bit of software. Everything included

  4. Built a similar scope in the early 90’s as my first and own big project. It worked, sort of. I don’t know the IC numbers but I used two older projects together: a VU-meter and a Knightrider running LED as my Y and X drivers. Stitched together with an array of transistors and a lot of soldering it worked OK-ish for audio. But I was proud of it.

  5. In the late ’70s I built a crude LED scope using the LM3914 of my own design. I seem to recall it had a 10×10 LED screen, with plans to upgrade it with two LM3914 and different chips for the horizontal to get 20×30 LEDs. I had worked out how to make the LM3914/5/6 smoothly change from one LED to the next, so behind a sheet of paper as a diffuser, it looked like an analog change in vertical. I used a 555 as the clock, and pretty sure I used an LM4017 as the horizontal scan. No idea the bandwidth, had to be pretty low.

    Sadly, I moved out to go to tech school and left a bunch of stuff behind. My parents tossed nearly all my electronics stuff in the trash, on advice of my uncle. My uncle though he was hot snot on a plate, because he worked for a company fixing huge computers. But all he did was replace boards, and he’d find out which was bad by disabling the overcurrent protection, and replace whichever board blew flames out of the tantalum capacitors.

Leave a Reply

Please be kind and respectful to help make the comments section excellent. (Comment Policy)

This site uses Akismet to reduce spam. Learn how your comment data is processed.