LaserOscope II

DIY Simple Analog Oscilloscope With a Scanning Laser Built From a Pile of Toys

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Build a simple analog oscilloscope with a scanning laser from a pile of toys (Snap Circuits, Lego, Erector Set).

Follow me on Twitter: @SteveSchuler20 and right here on Hackaday: KRA5H

My original LaserOscope was featured on Hackaday. Ethan Zonca, author of the article wrote the following about my LaserOscope:

"If you’ve ever used an old-school analog oscilloscope (an experience everyone should have!) you probably noticed that the trace is simply drawn by a beam that scans across the CRT at a constant rate, creating a straight line when there’s no signal. The input signal simply affects the y-component of the beam, deflecting it into the shape of your waveform. [Steve] wrote in to let us know about his home-built “oscilloscope” that works a lot like a simple analog oscilloscope, albeit with a laser instead of a CRT.

[Steve]’s scope is built out of a hodgepodge of parts including Lego, an Erector set, LittleBits, and a Kano Computer (based on a Raspberry Pi). The Pi generates a PWM signal that controls the speed of a LittleBits motor. The motor is hooked up to a spinning mirror that sweeps the laser across some graph paper, creating a straight laser line.

After he got his sweep working, [Steve] took a small speaker and mounted a mirror to its cone. Next he mounted the speaker so the laser’s beam hits the mirror on the speaker, the spinning sweep mirror, and finally the graph paper display. The scope’s input signal (in this case, audio from a phone) is fed into the speaker which deflects the laser beam up and down as it is swept across the paper, forming a nice oscilloscope-like trace.

While [Steve]’s scope might not be incredibly usable in most cases, it’s still a great proof of concept and a good way to learn how old oscilloscopes work."

One of the commentators pointed out:

"What an incredibly complex way to do a simple task! A 32-bit computer with 512 MB of RAM and a multitasking operating system does nothing but blink an LED, which through an optocoupler and amplifier, drives a motor. This much could be done with a battery, a variable resistor, and a motor. And he didn’t just use a $30 Raspberry Pi, he used a $150 kit that includes an RPi for this task, in addition to at least $100 for Little Bits kit.

But all of that aside, I don’t understand why [Ethan Zonka] refers to this project as a “home-built ‘oscilloscope’ that works a lot like a simple analog oscilloscope”, when it IS in fact an analog oscilloscope, by pretty much any reasonable definition of ‘oscilloscope’."

Yes, it is expensively over-engineered. The actual point of this build was to demonstrate optocoupling (I got tired of building magnetic stirrers and wanted to try something completely different). There are much simpler ways to demonstrate optocoupling, but how often does one get the chance to build an analog oscilloscope out of a disparate pile of toys, however Rube Goldberg-esque, just for fun?

In my previous project "An Experiment to Combine Lego and Snap Circuits" I designed a simple Snap Circuits circuit to spin a mirror and in this project I'm revisiting the Laser oscilloscope proof of concept with a lot fewer parts.

Build the graph paper target

The graph paper screen is easy to build with a piece of cardboard, graph paper, and a large binder clip:

I used a magnetic chip clip to clamp the laser pointer switch (a press switch) in the on position and attach the laser pointer to the Erector set mount. Unfortunately, there are plastic grips on the chip clip that interfere with the smooth rotation of the chip clip against the Erector set strip. So, I added a neodymium magnet from a magnetic keychain that I took apart and the keychain magnet lets me smoothly rotate the chip clip.

Parts Needed:

Magnetic chip clip

(Optional) neodymium magnet

Erector Set Parts:

1 Strip, 1 1/2", 15 hole

1 Base plate, seven hole by five hole

2 Triangle brackets

4 Small bolts

2 Medium bolts

6 Nuts

12 washers

1 Spanner

1 Hex wrench

Speaker Mount

Parts Needed

Erector set right angle bracket 3-hole (mine is a bit more than 90°)
Erector set nut
Computer case thumbscrew
Chip Clip

I used a knife...

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  • Basic Parts of a Laser Oscilloscope

    Steve Schuler06/10/2016 at 19:12 0 comments

    To build a laser oscilloscope you'll need five basic parts: a cat toy (laser pointer), a speaker with a mirror fastened to its cone, a sound source (I used a tone generator on my iPod touch), a spinning mirror, and a target screen:

    How you choose to build it is really up to you (depending on what materials you have on hand). I chose to use Snap Circuits and construction toys because they don't require power tools, or a soldering iron to construct them.

  • Added this project to Citizen Science and 2016 Hackaday Prize.

    Steve Schuler06/10/2016 at 14:40 0 comments

    I have added this project to Citizen Science and 2016 Hackaday Prize.

    We are starting to see an alarming decline of science literacy in the United States. The US continues to be the most scientifically and technologically advanced nation on earth and continues to lead the world in science and technology output. But as Niall Ferguson, the Laurence A. Tisch Professor of History at Harvard University, observes:

    “It’s certainly true that U.S.-based scientists continue to walk off with plenty of Nobel Prizes each year. But Nobel winners are old men. The future belongs not to them but to today’s teenagers....Every three years the Organization of Economic Cooperation and Development’s Program for International Student Assessment tests the educational attainment of 15-year-olds around the world. The latest data on “mathematical literacy” reveal that the gap between the world leaders—the students of Shanghai and Singapore—and their American counterparts is now as big as the gap between U.S. kids and teenagers in Albania and Tunisia." Source

    China is catching up to the United States according to the National Science Foundation. Nonetheless, though we have a number of serious issues we must confront such as global warming, we do have immediately pressing issues such as confronting anti-science movements like anti-vaccine, anti-GMO, and chemophobia (think Vani Hari a.k.a. “The Food Babe”).

    Lack of science literacy causes fear of GMOs, yet the lives of 2.7 million children could be saved with Golden Rice.

    Because of the lack of science literacy, people believe the Measles, Mumps, and Rubella (MMR) vaccine causes autism (it does not). Measles was wiped out in the United States by the year 2000, but “we had 644 cases in 27 states in 2014, the most in 20 years.

    With the impending public health threat of the Zika virus disease spread by the Aedes aegypti mosquito and can be spread by the Aedes albopictus mosquito as far north as the Great Lakes, it may be necessary to use the insecticide DDT. That’s right, DDT. It was banned in 1972 due to pressure from environmentalists based on bad science even though it is safe to use as an insecticide. Millions have died (mostly children in Africa) from Malaria. According to Marc Gwadz of the National Institutes of Health, “The ban on DDT may have killed 20 million children.” DDT is not carcinogenic nor toxic and can be consumed in significant amounts with no ill effects (if you don’t wash your vegetables before you eat them—you should wash them considering how many dirty hands have handled them before reaching your kitchen…ewww!). Of course, the scientifically illiterate chemophobes will intransigently parrot Vani Hari, “there is no acceptable level of any chemical to ingest ever.”

    Immunizations, food security, and mosquito control are immediately pressing issues that can save millions of lives globally. Science literacy is the best defense against cranks, charlatans, and pseudoscientific demagogues.

    Information wants to be free

    So much scientific research is locked up behind paywalls even when that research was paid for with public funds.

    There is so much competition for public grants among scientists that they seem to only want pursue research that is "sexy" and likely to published in the most prestigious of journals--even when that research is flawed and sometimes dangerously fraudulent. Andrew Wakefield's MMR autism study was published in The Lancet in 1998 and was retracted in 2010 but to this day people still believe the Measles, Mumps, and Rubella (MMR) vaccine causes autism.

    There is a growing citizen scientist (amateur scientist) movement spawned from the maker movement that is similar to the Gentleman and Lady scientists that preceded the Age of Enlightenment and before the professionalization of science. Citizen scientists are doing research that often rivals professional scientists and publishing their research in open journals...

    Read more »

  • Main LaserOscope II Article is Completed (Mostly)

    Steve Schuler06/10/2016 at 13:03 0 comments

    The main part of my LaserOscope II article is completed. It needs a bit of tweaking so I'll continue to try to improve it. If anyone has suggestion for improvements to this article please post your suggestions, complaints, stuff that you might be confused about (whatever I have failed to make clear), etc. in the comments. If you like this project, please don't hesitate to click the like button.

    The postulated audience for this project are parents who are STEM (Science, Technology, Engineering, Math) workers, K-12 educators, post-secondary educators, homeschoolers, and DIYers/Makers/Hardware Hackers.

    Snap Circuits is recommended for ages 8 or older but of course it would be up to parents to determine if it is appropriate for children younger than 8 (NOTE: project does include small parts. And frickin' laser beams).

    As it says on my profile: "You may try my projects AT YOUR OWN RISK--there are infinite ways to damage or destroy people and property, I can't think of them all."

  • Added circuit to spin mirror

    Steve Schuler06/08/2016 at 19:47 0 comments

    Added circuit to drive the Lego mirror spinner using Snap Circuits.

  • Lego Mirror Spinner

    Steve Schuler06/08/2016 at 17:35 0 comments

    Added section for Lego mirror spinner.

  • Added Snap Circuits/Lego base plate section

    Steve Schuler06/07/2016 at 19:26 0 comments

    Added section to demonstrate how to connect the Snap Circuits base plate to the Lego base plate.

  • Added how to mount the speaker

    Steve Schuler06/07/2016 at 16:59 0 comments

    Added section to demonstrate how to mount the speaker on the Erector Set/chip clip stand.

  • Added speaker mount section

    Steve Schuler06/07/2016 at 14:13 0 comments

    Added section for Erector Set (Meccano) and chip clip mount for speaker.

  • Added laser mount section

    Steve Schuler06/06/2016 at 21:00 0 comments

    Added magnetic cat toy (laser pointer) mount section.

  • Added Laser Target Build Section

    Steve Schuler06/06/2016 at 18:42 0 comments

    Added instructions to build the laser target.

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Steve Schuler wrote 06/17/2016 at 11:07 point

Thanks, Jerry, for liking my project!

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Tracy Scott wrote 06/16/2016 at 12:25 point

What a neat idea! This is something a lot of us could have fun with and use.

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Steve Schuler wrote 06/16/2016 at 12:41 point


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Steve Schuler wrote 06/16/2016 at 12:42 point

And thanks for liking my project!

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Thanks, Noelle, for liking my project!

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