“Making the world a better place, one mad scientist at a time”
Evil Mad Scientist Laboratories develops many gizmos to let microcontrollers help or be artists, to magnify integrated circuits into a giant-sized DIP. They are really fun and worth looking over. They celebrate the maker community and its artistic talents.
One regular series on the blog is a monthly link dump. I’ve collected links to them on a page here.
The link dumps are always interesting and I hope you enjoy them as much as me.
I had a USB hub fail yesterday. The 3 external drives connected through the hub all disappeared from my system. I almost went into panic mode when I moved the external drives’ cables to a new USB hub and they were still were not working. However, I knew some keys to the process.
tl;dr: Restart has benefits that shut down/power up do not. Make one change at a time.
In Windows, the process of moving a drive from one USB port to another can be fraught. I have seen this problem in the past. I don’t know the exact reason Windows has this behavior.
When the hardware configuration changes, the naïve way of just unplugging the drive from one port and installing the cable in another doesn’t always work. When there is a problem, Device Manager might show the drive, but it could have a error flag. [See below for an easy way to launch Device Manager.]
Before pulling out the heavy guns on the problem, it might be that some simple steps are enough. Some actions unlikely to succeed:
Some of these are suggested as the first line of defense, but I’ve found them unhelpful when USB drives are not recognized.
Device Manager can show your progress but you do not need to make any manual changes there. Especially true: Online help that says you should download and install special tools shouldn’t be trusted.
The two keys are
Shut down/power up is safe but sometimes a restart is still needed.
The steps I took to successfully transfer the drive is as follows. It’s wiser to disconnect/reconnect while the power is off, but Restart is still needed after the power is turned on.
At this point the device manager showed the external drives under the “Disk drive” category.
I was disappointed that, at first, Windows didn’t show the drives in Explorer and Device Manager didn’t show any errors. To fix this didn’t require any extra magic steps. I did an extra restart and shut down the system and turned off the power strip. I did not change anything in administrative tools nor device manager.
My point in this description is to explain that the error when I moved a drive from one USB port to another required some extra steps but no wizards hat.
A similar problem can happen when you move a USB hub from one USB port to another. That also requires multiple reboots. You just make each change one at time.
Fortunately, changing usually works without any trouble. Unfortunately, when you do have trouble, many online help sites give identical suggestions that don’t work. The pedestrian steps of change, restart, change, restart can be enough.
To launch Device manager in windows 10, just go to search in the taskbar and type Device Manager. You can also search in the configuration tool (the gear in the start menu). You don’t need to remember the name of the tool’s file any more.
Two of the fiction in the July 2020 issues of The New Yorker are Jack and Della by Marilynne Robinson was published July 20, 2020 and The Lottery by Shirley Jackson, originally published June 26, 1948 was republished July 27, 2020.
The story Jack and Della is a melancholy story about a young man who had recently been released from prison. He meets the teacher Della, and has a positive relationship with her. The story ends very sadly and the desperation and loss really touched me.
In the article, Marilynne Robinson on Expanding the World of ‘Gilead‘ also published July 20 discusses Jack’s position in the “Gilead” series of novels. In the first novel in the series, “Gilead,” Jack is a respectful and mysterious man who comes home to his family and then disappoints his family by leaving abruptly. He isn’t able to explain himself to anyone other than the minister John Ames. The fiction Jack and Della is adapted from the fourth book in the series, “Jack.”
The Lottery is disturbing and has the distinction of generating the most mail for a fiction piece. (“The Lottery” Letters) To me it ends very unsatisfying. The events that conclude the story are taken so matter-of-fact by the community and the anticipation of a horror as if it were a natural fact of life.
[Many of these links may require a subscription to The New Yorker.]
I wanted to explore my speaker’s directionality by making a jig that could hold the microphone in fixed relative positions to the headphone. My overarching goal was to be able to isolate the behavior of the microphone from the behavior of the headphone speaker.
This is what I came up with. The use of hard, rigid, flat surfaces is significant, but not in the way I anticipated.
The slotted food boxes make a rigid frame with holes to allow the microphone to be placed in different positions. The shipping box is marked with a pencil outline so that the headphones can be placed consistently. The edge of the box fits against the slotted structure. I only used the speaker on the side that faces the microphone. I didn’t use the perpendicular speaker nor the microphone on the headphones.
Again, I did a sweeping sine wave. When I analyzed the results, I found an interesting waveform around 120Hz. In the first graph, the frequency was sweeping from about 118.8 Hz to 121.2 Hz. At first I thought that what I saw was some kind of audio interference pattern. But that didn’t make sense because the graph shows large changes between slight frequency changes (and thus slight audio wavelength changes.)
This graph covers about 33.5 seconds of recording. By slowing down the rate of change of the frequency, there are more samples over the course of the transition and noise interferes less. (The spike to the left was due to noise from a car passing or me moving on my chair.)
I was trying different adjustments to the configuration to identify the parts that are responsible for the resonance. My first try was apply force to the front wall of the food containers. This had only a small effect on the behavior. My second adjustment was to place crayons on the box out of the line of sight between the speaker and microphone. The resonance was completely gone in that case.
The third adjust I tried making was to put some weight on the box, also out of the line-of-sight. I placed several CD discs on the box. The lower one had some CDs laying on the box and there is an obvious change. The graphs aren’t synchronized.
What I understand now is that these effects are due to resonances within the box that the headphones are on or between the headphone’s strap and the box. Changing the forces on the box caused substantial changes.
Another way that I visualize the data is to break the signal into equal sized blocks of time and perform a Fourier transform of the block and plot them as an image. Pixels closer to the bottom edge of the graph represent lower frequency components of the signal.
I found this strange shape in the first graph I created. I created graphs from other runs and none of them had anything like this.
Then I remembered a fire truck siren that I heard a few blocks away when I was recording one of the results. It’s interesting to see the shape. It’s a repeating pattern of the tone rising rapidly, followed by the tone falling more slowly. I notice that that the same shape is repeated twice with difference delays which indicates there were two sound sources cycling at different speeds.
I had other things happen that I wasn’t looking for as well.
I received a text while I was recording.
There were several smudges like this next one in the plots. They are due to cars passing. I was recording in the daytime so there was more traffic than at night.
There is an unlimited list of sounds that I could analyze to see more interesting patterns.
I ended up finding another rabbit hole just by looking at one position of the microphone and haven’t explored how other positions differ. However, I may have seen enough to know that I haven’t found the key to need to isolate the speaker from the microphone. Without a more sophisticated setup, the environment is going to be a confounding effect. In addition, my jig only works with one microphone and different speakers can’t be positioned with an equivalent geometry.
W. Smith 