Hackaday Podcast 100: Arduino Plays CDs, Virtual Reality In The 60s, And Magical Linear Actuators

Hackaday editors Elliot Williams and Mike Szczys kick off the first episode of the new year with the best hacks the internet has to offer. There’s a deep dive into water-level sensing using a Christmas tree as an excuse. We ooh and ah over turning a CD-ROM drive into a CD player (miraculous tech of the previous century?). Do you have any use cases for ATtiny oscillator calibration registers? We look in on a hack that makes it dead simple to measure and set their values. The episode finishes up with a discussion of the constantly moving goal posts of virtual reality.

Take a look at the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

Direct download (~65 MB)

Places to follow Hackaday podcasts:

Episode 100 Show Notes:

New This Week:

  • Elliot’s been rebuilding his CNC foam cutter
  • Mike’s getting closer to a proper automated backup system

Interesting Hacks of the Week:

Quick Hacks:

Can’t-Miss Articles:

16 thoughts on “Hackaday Podcast 100: Arduino Plays CDs, Virtual Reality In The 60s, And Magical Linear Actuators

  1. ATAPI (AT Attachment Packet Interface) is an interface between your computer and attached CD-ROM drives and tape backup drives. Most of today’s PC computers use the standard Integrated Drive Electronics (IDE) interface to address hard disk drives.

  2. Regarding capacitive water sensors for plants, check this out:


    The pF is a concept of water “pressure” in the soil, or rather how much the soil resists the plant pulling the water out of the soil. It’s expressed in units of pressure, and it depends on the soil type, temperature, density, salinity, acidity, etc.

    You can get a pretty close approximation of the water content between two capacitor plates – it’s the change in the dielectric constant, minus the effect of conductivit etc. which you can measure. However, the relationship between volumetric or gravimetric water content and pF is the point where you get into real “voodoo” – you have to characterize the soil and the plant to know what is the wilting point and where the roots start to drown. It has nothing to do with the idiosyncrasies of the sensor – you can have the best moisture sensor and it will still tell you nothing because you aren’t controlling for the soil conditions.

    Much money and time has been spent in developing sensors for agriculture, and it’s still mostly guesswork.

  3. Sorry but you’re wrong regarding the filming of the Boston Dynamics video. If you look closely, the yellow-transparent wall actually has enough reflection that towards the middle of the video you can clearly see a walking camera man with a gimbal and probably a safety person escorting him around. It is very well coreographed, but Boston Dynamics robots are probably safe enough that humans can be near them with proper precautions. This makes it even more impressing though.

  4. Regarding the Boston Dynamics robots dancing.

    I think you commentary of the premise is correct, you want to make the public feel safe about being with the robots, the point was missed when you describe how dangerous of machines these are, with an air of uncanny valley mistrust of them. Boston Dynamics is working on the kinematics of robots specifically, where the AI of any sort of thinking or rationality is no where even in the picture.

    Early videos of the robots Boston Dynamics was developing shows people physically “spotting” the robots just in case it fell and damaged itself in the same way a gymnastics coach spots a gymnast while learning a difficult flip. As soon as the training wheels come off, the coach is no where in sight. I have to believe that this was the goal for Boston Dynamics, to show how far their robot kinematics has come.

    I would also venture the guess that the cue marks on the floor are designed more as a reference of where the movement is starting so they have an idea that the robots wont wander to the edges. And as far as the enclosed space? While yes, you don’t want the robot to physically collide with someone, I don’t think that this is designed for safety of people, but more to have a completely controlled space. I agree that this was probably choreographed by having people with tracking suits do the actual dance eliminating the need to write such complicated movements, I also would bet that those same cameras are part of the control loop to help the robot with position/orientation/balance while executing the routine. I think that the robots are way past doing clumsy unpredictable movements that could hurt someone.

    While this was super impressive and quite the achievement, it would be really cool if they kept on pushing the dance boundaries further. I would really be impressed (I am already impressed but would be more so) if the robot did some breakdancing routine, shuffle, or popular meme dance like the fortnite ones (I’m sorry if I offended anyone with that, hahh). It would be cool to see things on the outer fringes of human dancing ability executed by these robots. Or even more impressive, seeing the robot pulling off dances that require human to human interaction, like ballroom dance or social dancing, where one person takes on the lead role and the other follows. The robot could be the ultimate leader or follower with an actual human!! This to me would really go a long way in showing that “these robots aren’t scary.”

    1. >I think that the robots are way past doing clumsy unpredictable movements that could hurt someone.

      On the contrary, they are now fast and powerful enough to smack you around the head with enough force to kill you, thanks to the new actuators that allow them to make these moves.

      They lack awareness of their surroundings – they won’t even feel anything when they hit you because their “skin” has no pressure sensors. This is the unsolved problem with industrial “cobots”, or robots that are supposed to co-operate with human workers on the same tasks – if you get in their way when they are performing their routine, they will just put a screwdriver through your hand or pin you against a wall and squeeze you to death. A robot arm moving at 1 m/s will continue to move an inch and a half in the 40 milliseconds it takes for the PLC to notice that the motor torque has suddenly increased and it needs to stop, by which time you’ve already broken your bones.

    2. > or social dancing, where one person takes on the lead role and the other follows.

      I would not want to see what happens when you step on its toes, and the robot starts its “flail around like bambi on ice” routine to regain balance. There’s an 80% chance the dancing partner would get broken ribs.

        1. Well, we pretty much need the AI to make sense of the sensors as well.

          There are all sorts of proximity sensors, but they’re kinda flaky without a “brain” that understands what it all means and can predict what’s going to happen next.

  5. Can you guys upload podcast episodes to YouTube? If not, can I? I like to listen to them on my TV and my “smart” TV doesn’t like audio files but has no problem with videos.

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