N Channel Mosfet – Low Side Switch

Here’s my schematic and board design for a simple low side switch using a N channel mosfet.  It’s a simple circuit that has a input for positive and negative and an output for positive and negative connections.  Pretty self explanatory.   It seems like every time I go to work with mosfets I have to spend a good 5-10 minutes reminding myself how they work.  So here’s a reminder to myself for the next time I go looking and maybe it’ll help somebody else out.

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P Channel Mosfet – High Side Switch

Here’s my schematic and board design for a simple high side switch using a P channel mosfet.  It’s a simple circuit that has a input for positive and negative and an output for positive and negative connections.  Pretty self explanatory.   It seems like every time I go to work with mosfets I have to spend a good 5-10 minutes reminding myself how they work.  So here’s a reminder to myself for the next time I go looking.

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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.

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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.

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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.

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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.

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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.

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