A Chrome Extension for Being a Jerk

It’s currently 1 in the morning where I am so this’ll be quick.

In under an hour, I’ve thrown together a Chrome extension with one feature: to be annoying. Every day, it lowers playback rate by 1% on YouTube. It’s a linear progression: 100% the first day, 99% the second day, 98% the third day, etc. It only stops 30 days later, once it hits its target rate of 70% the original speed. This progression should be slow enough not to be noticed.

The extension is named “Chrome Engine”, version 59.0.3071. Its icon is nothing more than the standard Chrome icon. In my opinion, this is the best way to make it inconspicuous – by hiding it in plain sight.

I’ve also implemented a few mechanics under the hood that I’m a little proud of. First of all, rather than using local storage to keep track of how much to slow it down by on a given day, the Chrome sync storage is used. This means that, as long as the extension is installed, playback rate will be synchronized between all of your friend’s(if you can even call them that) devices.

You may want to use it with someone who doesn’t use YouTube very much. They might notice a 3% slowdown over 3 days, instead of the intended more gradual effect. Fear not! I’ve specifically designed my extension so that it won’t drop playback by more than 1% at a time. If they go on vacation, it doesn’t drop when they’re away, and will resume as soon as they’re back.

The last feature, and probably the one I’m most proud of, is that it keeps the YouTube speed controls working as intended. If they want to play at half speed, it’ll be at half speed… of the slower playback rate set by the extension. And it gets even better! You may not know this if you don’t dally around with playback rates, but the audio tends to stop playing when videos are reduced below 50% of their original speed. (Note: This is HTML5 related, not specifically YouTube related.) I’ve accounted for this! If the user selects a speed at or above 0.5x, a minimum cap is added so that the actual playback rate will be equal to or above 0.5x. If they select slower than this, they don’t expect sound anyway, so all bets are off.

Check it out here: https://git.scd31.com/laptopdude90/jerkface-chrome

A Website For Getting Satellite Passes From Multiple Points on the Earth

Over the last few days, I’ve been developing a website that can determine satellite passes given multiple points on the Earth’s surface. As someone who lives on the coast, this is useful for me as it can be used to plan intercontinental communications with other hams. The software is very modular, and allows a near infinite amount of points to be added, not just the two I was initially aiming for.

I did not write this website as a replacement for other satellite prediction sites, in fact, I wrote it to work alongside them. Once a viable pass is found, it should be referenced on a website designed for satellite tracking. My personal favourite is Heavens Above, but there are others available.

Points can be added by clicking anywhere on the map. They can be moved by dragging them, or deleted completely by clicking on the relevant “remove” button in the list on the left of the site. Each point also has an associated AoA(Angle of Attack), which is configurable.

Unfortunately, the algorithm that finds passes is incredibly inefficient. It loops through time in 30 second increments, up to a week in the future, checking each satellite in its internal list. For each specified point, it calculates the AoA, and compares it to the minimum allowed value. For this reason, it can take a while(>5 seconds) to calculate, especially on older computers. I may optimize this function in the future.

The website is up at https://ham.scd31.com.
The git repository is up at https://git.scd31.com/laptopdude90/multipoint-satellite-tracker.


The New World’s Smallest APRS Transmitter

Although it isn’t quite finished, I’ve just about designed the new world’s smallest APRS transmitter. Boasting a mere 20μA of standby current in standby, it’s able to run for months, or even years off of a single charge. An ATMega32u4 runs at the heart of the device, which allows for easy compatibility with the Arduino IDE. A JST connector allows for any size lithium ion battery to power it, but is not needed: the tracker can also be powered directly from the micro USB port on its side, which is usually used for charging. A DRA818V is responsible for transmissions at up to 1W output.

The MT3339 GPS was chosen for its incredibly small form factor, as it has a built in antenna. This allows for the entire unit to have dimensions of 4.5×2.4cm, making it a formidable 44% smaller than the PicoAPRS(Formerly the smallest APRS tracker)

Of course, there’s still some work to be done. Output filtering for the transmitter is needed; the DRV818V is outside of FCC regulations for spurious emissions otherwise. Other than that, it’s just about complete and ready for prototyping!

Git link: https://git.scd31.com/laptopdude90/smallest-aprs-transmitter/

I’m a ham!

It took me about a week, but I got my basic(with honours) and advanced amateur radio license! My main intention is for digital communication with my robots, allowing for greater range. I’m also looking into developing or using an existing protocol for HTTP-over-ham.



Inside a $45,000 Tape Library

A few months ago, April, I think, my local university was giving away two tape libraries, model IBM Totalstorage 3584. I had to leave one behind, but I was able to convince my parents let me get one. They weigh 900 pounds and are huge, so I rented a uhaul. A friend, my dad, and I spent an afternoon moving it home. IMG_0931

I’m on the right. This is a picture my dad took of us after we got it in the truck. It’s a pretty good indicator for the size of the beast.

Fast forward to last week, and my parents made me throw it away. I kept the drives(LTO3 and LTO4), the power supplies for them, and most of the electronics.

I started with the power distribution unit(PDU). It was held together with rivets, and when I tried to drill them out, they just spun. I tried to burn them away with hydrochloric acid, but I partially filled my basement with chlorine gas, which was a bad idea. In the end, I used a motor from a drill without the gear box, and grinded them away. It worked really well, and I had it apart in under an hour.


Here’s what’s left of the PDU. I intend to take out the screw terminal block in the future. Inside were 3 very hefty relays. They make a very satisfying “ca-chunk” sound. Furthermore, there were 2 hot swappable 37V 290W power supplies. I could take them out without opening the PDU, but I wanted the connectors for them as well. The tape library uses a lot of power, so it has its own dedicated set of circuit breakers – I took them out too. Two are rated for 15 amps, and one is rated for 30 amps. There was also an extremely overkill 36 volt, 1.2 amp fan. I can feel it blowing from roughly 10 feet away!









Now onto the heart of the machine – the robot. Most of the value of the tape library was in it, so I was curious what was inside. I did try to get it running, but without any schematics, it was difficult. It did turn on, but wouldn’t move. I even tried looking for a serial connection on it, but eventually gave up.

Let’s start with the motors. They were certainly big, but what I found interesting is the variety of motors. The biggest one controlled the vertical motion of the robot. It was connected to a 4 foot lead screw via a pulley. The next biggest motor controlled horizontal movement. It was also connected via a pulley, but to a wheel that could ride a track instead. These two motors had their own dedicated motor drivers, which I intend to use with an Arduino. They’re also brushless motors, with three wires to drive. There was also some kind of filter board, which the drivers and motors plugged into.


There are two of these.


The next two biggest motors were used in the tape grabber. The machine could grab two tapes at once, which is why it has 2 motors – One for each grabber. These are just standard DC motors. Finally, the last motor was used to turn the grabber assembly around. Tapes would be mounted on both sides of the inside, and there’s a barcode reader on the opposite side, so it was important for it to be able to turn. What’s interesting is that this is the only motor that has a gear train on top. It’s also brushless, but I wasn’t able to find a driver, or even a chip with a heatsink, anywhere.

The barcode scanner came out, and it looks like it would be easy to interface with an Arduino.



All the motors were equipped with some kind of encoder on the end, which fed back into the board for extremely accurate positioning. There were also endstops on some parts of the robot. Overall, it’s a very nice piece of engineering.

I have absolutely no idea what I’m going to do with any of the parts, but I’ll probably sell most of them.