Prototype complete: bag movement alarm

After figuring out the modified power circuit and the battery power monitor circuit, I could finally finish the prototype of the bag movement alarm.  I also added the same power switch circuit for the speaker, which allowed me to use a much better speaker (when I had tried it before with the old power circuit, it beeped…

Power monitor circuit

For the bag movement alarm project, I wanted to be able to monitor the battery level so I can warn the user when they need to change the battery.  A simple way to do this is just to monitor the voltage of the battery, as batteries have a pretty well articulate discharge curve:  with more…

Power circuit redesigned!

When I integrated the TrinketPro into the bag movement alarm prototype project, the power circuit did not work.  So I needed to redesign the power circuit. I had posted a question about this in the Arduino.cc forum, where forum user dlloyd had helpfully pointed me to an excellent explanation of using MOSFETs as power switches.…

Replacing the Uno with the TrinketPro

Now that I have the TrinketPro working fine, and have the sketch and prototyped circuit for the bag movement alarm project using an Uno, I wanted to replace the Uno with the TrinketPro. There were a few small changes, as there are two pins on the TrinketPro that are not available:  #2 and #7.  Since…

Trinket Pro ‘unboxing’

As part of the hackaday.io Everyday Carry contest that I am (in part) building the bag movement alarm for, I need to utilize a Trinket Pro.  Which is fine, because the product itself is a pretty affordable ~$10, and it packs pretty much to same punch as an Arduino Uno. I ordered one from the…