Radio Shack 4x2x1 Enclosure Dimensions

I recently needed to use this enclosure from Radio Shack.  I’ve seen them used a ton over the last couple decades but somehow couldn’t find the dimensions, especially the hole spacing.  So I got out my trusty dial calipers and and made my own.  Hope this helps somebody else.

Continue reading “Radio Shack 4x2x1 Enclosure Dimensions”


Storing GPS Location in Photo Pixels

A few years ago I was working on a project using a multi-rotor UAS to monitor weather.  While out in the field, the user needed to be able to see the location of the UAS on a satellite map.  The UAS had a GPS and was capable of transmitting that back to the laptop running custom ground station software; however, a constant connection to the internet would be necessary to get satellite maps from Google and many places this would be used won’t have a reliable signal.  So I rolled my own solution to fetch the map from Google ahead of time and save it as an image file, which works fine since the location would be known in advance.  The challenge was that I needed to have GPS coordinates associated with the image.  Instead of having the GPS coordinates in a separate file, I decided to alter the pixels in the image to store the GPS coordinates so that only one file was necessary.

Continue reading “Storing GPS Location in Photo Pixels”

Reflectance Sensor Array with RPR-220

I’m working on a robot project and one of the intended uses is to teach line following to college students.  For this, I’m making an array of 9 RPR-220 reflectance sensors.  This post will describe the part I’ve designed and the reasoning behind it.  It’s a bit rambly so consider yourself forewarned.

Continue reading “Reflectance Sensor Array with RPR-220”

TB6612 Update – Does It Need Diodes?

Several months ago I wrote a post about a breakout board for the TB6612 motor driver.  You can find that here.  The reason I made my own breakout board for this was that the ones available from Sparkfun, Adafruit, and Digikey didn’t have diodes on the board.  The TB6612 says it has internal diodes but those are small and I saw somebody online suggest always using external diodes.  Today I realized I wasn’t sure if I actually needed them or not so I decided to do my own test to find out.

Continue reading “TB6612 Update – Does It Need Diodes?”

IHG Priceless Surprises Monte Carlo Simulation

Over at One Mile At A Time, they did an analysis of the recent IHG Priceless Surprises Promotion where you could mail in 94 entrees and get back 94 plays in an online game.  Most entrees only won 500 points but some won 1000, 2000, 5000, and a few won free nights or gift cards.  I liked his analysis and it got me thinking about possible wins and the distribution.  Instead of doing a bunch of math, it was easier to create a Monte Carlo Simulation and the results were a little surprising.

Continue reading “IHG Priceless Surprises Monte Carlo Simulation”

Simple LiPo Battery Charger with the MCP73831

The little board was built to charge a single lipo battery using the MCP73831 from Microchip.  I plan to use it along with several other boards featured on this blog in a larger project, but I like to break things up and make sure they’re working individually before making them work together.   Continue reading “Simple LiPo Battery Charger with the MCP73831”

Simple Boost / Step-up DC-DC Converter Using the NCP1402

If you’ve read much of this blog, you’ll have noticed that something I like to do is test ideas on simple breakout boards before implementing them into larger projects.  If something goes wrong, I haven’t wasted a bunch of time/money on it.  And if something goes right, then I’ve got an example that I can keep around which will help next time I need to implement that particular part.  This post shows my breakout of the NCP1402 boost converter that takes inputs from 1-4V and outputs 5V at up to 200mA.

Continue reading “Simple Boost / Step-up DC-DC Converter Using the NCP1402”

TB6612FNG Motor Driver Breakout Board

Part of a robot controller I’m currently working on involves using some motor controllers.  Since this robot controller is expensive and I’ve never worked with h-bridges (other than in professional products) I decided to make a breakout board to test it rather than risk making a stupid mistake on the robot controller.  Luckily, it all worked perfectly so I’m sharing it with the world so that other people can learn from it. Continue reading “TB6612FNG Motor Driver Breakout Board”

Using the RPR-220 and a Breakout Board

One of the projects I’m working on is a robot that has reflectance sensors around its circumference.  I had trouble finding sensors that would work in the 0.25-0.75 inch range but eventually found the RPR-220.  To mount this sensor, I made a breakout board with space for resisters and connections for positive, negative, and signal. Continue reading “Using the RPR-220 and a Breakout Board”