Rocketbook App: Changing the resolution

I recently purchased a Rocketbook Everlast, which is a reuseable notebook that can be written on, scanned with a cell phone using the Rocketbook app, and then erased with a damp cloth. It’s like having a portable whiteboard, except that it looks and feels like a notebook, and the integrated app makes scanning and organizing notes very easy. I’ll eventually write a detailed review on it, but for now I wanted to share my experience with changing the Rocketbook app’s resolution setting.

(Note: This only applies to the Android version of the app; the iOS version does not allow the resolution to be changed. See the RocketBook FAQ for more details.)

The app defaulted to a resolution of 2592 x 1944, which is only 5MP. My phone (a Moto G4 Play) has an 8MP camera, so I changed the setting to 3264 x 2448 to match it. Here are samples of a page I scanned at both 5MP and 8MP (click to see full-size):

Rocketbook resolution comparison 5MP vs. 8MP

For both sample images, I attempted as best I could to shoot from the same angle and distance. I then exported to PDF and viewed them at 300% zoom for the full-size sample images. The image taken at higher resolution is noticeably smoother, as expected. It doesn’t make a huge difference, especially when viewing at a normal zoom level. But it’s still quite noticeable.

Based on my results, I think it’s well worth it to check this setting after installing the app and see if you can increase the resolution. It’s found by clicking on the gear icon at the top left of the app and then going to Advanced Settings. It only takes a minute and can really improve the quality of your Rocketbook scans!

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Power & Temperature Monitoring System

I developed a power and temperature monitoring system for work a few months ago. It’s based around a Raspberry Pi, some other components and a program I wrote in Python. This was a lot of fun for me, as it gave me a chance to combine my “day job” skills as an IT administrator and programmer with my interest in hobby electronics. The resulting system turned out really well and has worked great so far. In this article I’ll cover what the system does, the parts that went into building it, and of course the source code and related information will be provided for those wishing to build upon what I did.

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Cloud Nightlight Color-Changing LED conversion

Big Clive recently reviewed a cheap cloud-shaped nightlight from China, and later recorded a video showing how to convert it to use color-changing RGB LEDs:

I wanted to build one myself, and already had the LEDs, so I ordered a cloud nightlight from China. It was a little less than $2.00 USD shipped and arrived approximately 5 weeks later. Right away I had problems with it as it was damaged; the plug and circuit board were both loose. I was worried the screw that holds the plug might be stripped, but fortunately it was not and I was able to repair it. With everything in place, I tried it out, and it looks very nice:

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My 1989 IBM Model M Keyboard

Power Consumption of IBM Model M Keyboards

The IBM Model M keyboard is notorious for its loud clacking keys, solid construction and tactile feedback which has made it a favorite of many serious keyboardists despite the fact that its design is now decades old. Unicomp still manufactures Model M keyboards, and offers some modern updates such as Windows keys and a USB interface. This is a great option to have, but like so many others I still rely on older versions of the Model M that have a PS/2 interface, which is no longer included on mainstream computers. So an adapter is necessary, and there’s many out there to choose from. But as most Model M enthusiasts know, not all adapters work with the Model M.

The problem is that Model M keyboards consume significantly more power than modern keyboards, and not all adapters (or motherboards, for that matter) can provide enough current on the PS/2 port to power a Model M. I’ve known this for a long time, but never knew exactly how much current a Model M draws vs. a modern keyboard. I decided to find out.

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LED Light Bulb Kit from China

DIY LED Bulb Assembled

I’m a huge fan of Big Clive, and watch his videos regularly. Back in December he built a DIY LED bulb kit from China, and as soon as I finished the video I ordered a couple for myself! It’s a fairly simple kit with a lot of potential for customization. There’s a lot of solder joints but the overall assembly isn’t too complicated, and the theory behind how they work is fascinating and not too hard to comprehend. Best of all, with prices well below $2 shipped, they’re cheap fun! I recently assembled one of these kits so I can review it and share what I’ve learned so far.

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LED Test Box from China

LED Test boxThis little LED test box couldn’t be simpler – pop an LED into the tester, push the button, and see it light up. The top header accommodates standard LEDs with two leads, and the bottom headers accommodate 4-pin “piranha” LEDs. I use it frequently when assembling LED lighting projects or to quickly test a new batch of LEDs. It’s a great value for the approximately $2.00 USD that I paid for it. With that said it has some issues, and there are a few things to be aware of when using these testers.

Build Quality

You can’t expect much for $2, but the quality is fine for the price. The biggest issue I have is the headers; they don’t always make good contact with the leads on the LEDs, especially the bottom rows for piranha LEDs. So sometimes I have to fiddle around with the LEDs to get solid contact. The other minor issue is the battery compartment, it’s fairly tight and I’ve had some trouble figuring out how to best orient the battery so it will fit with the case closed. With a little trial and error though, it’s possible.

These are minor quibbles, and acceptable given the price. But there are some more concerning issues with the circuit itself, which I’ll cover in the next couple sections.

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Counterfeit DS18B20 temperature sensors

DS18B20 temperature sensor counterfeit vs. real
On the left, a relabeled transistor; on the right, an actual DS18B20.

As anyone who’s wanted to measure temperature with a Raspberry Pi knows, it doesn’t offer analog input. This means that the TMP36 sensor which is commonly used with the Arduino doesn’t work. The most popular option for the Pi then is the DS18B20, which is a digital sensor that utilizes the 1-wire interface and is natively supported by the Pi. It’s considerably more expensive than the TMP36, and as is the case when a component is expensive and in-demand, it’s prone to counterfeiting. I recently experienced this firsthand.

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“Old-fashioned” Bench Grinder stand

Bench Grinder closeupHere’s a project I completed last summer that I’m just finally getting around to sharing. It’s an “old-fashioned” bench grinder stand, or pedestal. I call it old-fashioned because I built it for a belt-driven grinder whereas grinders today are typically direct-drive.

The grinder itself is a General Hardware 6″ grinder with no model number. I picked it up at a garage sale for $5. I couldn’t find too much information on it, but what I did find indicates that it may have been manufactured any time between the 1950’s and 1970’s. I didn’t have a grinder, and I had some old utility motors laying around, so I figured it might be a cheap way to have one.

Bench grinderThe easy solution would have been to just mount the grinder and a motor to a board and be done with it, but I wanted something a little nicer. After scouring the web for awhile, I stumbled across this webpage which had plans for a pedestal grinder stand, scanned from a November 1971 copy of Popular Mechanics magazine. This was it! Some of the information was cut off, so to be sure I had all the information I needed, I purchased a copy of the magazine off of Ebay, made my own scans, and filed it away until I’d have time to build it. That time finally came when I walked out to the garage one Saturday morning feeling bored but motivated and looking for something to do.

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Elektrosluch – Listen to EMI

Elektrosluch completeMAKE recently featured a very cool project that I had to build: the Elektrosluch! What’s an Elektrosluch? It’s basically a microphone of sorts that allows you to listen to electromagnetic interference (EMI) which is found all around us in our personal electronics, homes, automobiles, and many other places. The Elektrosluch includes a built-in amp, so listening can be done with headphones, or it can be connected to a recording device for sampling. The tutorial was written by Jonas Gruska, who designed the circuit. It was a lot of fun to build, and overall not too hard. I took my time and checked everything several times and it worked the first time I tried it.

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Reload Controller

Earlier this year I purchased an Arachnid Labs Re:load Pro, which is an adjustable constant-current load. I’ve always wanted an electronic load for my lab, but didn’t want the spend the money. The Re:load Pro solved that problem as it’s just $125. Sure, it doesn’t sink as much current or have all the options of fancier units, but it does everything I need. For testing panel meters, batteries and LEDs, it’s quite capable. So far, I’m happy.

Reload Controller Main screenOne of the features that caught my interest when I purchased it was the ability to interact with it via a virtual serial port on the USB interface. I immediately got the idea to develop an application that could control a Re:load Pro, but didn’t have time to work on it. Recently however, I started working on serial port projects at work again, and I finally completed my serial port class, called dsub. I needed to test it, and I thought of the Re:load Pro. It was a perfect device for testing. I set about developing an app, and correcting some bugs in dsub along the way. The result is an improved dsub class, and a small application called Reload Controller which I’m releasing here. (more…)