Once upon a time, I had the idea of completely replacing the deadbolt lock on my front door with a solenoid. I knew how solenoids worked, but I had never played with one, much less programmed a board to make one work.
This project takes a switch and uses it to trigger the solenoid. My basic design premise was I wanted the door to always be locked if it was closed. It should only be unlocked when I pushed the button.
I later realized that if the house has settled to the point that the solenoid-powered deadbolt didn't line up in the doorjamb properly, the door wouldn't lock automatically because the doorjamb would prevent the deadbolt from traveling the full distance to engage. For maximum security, you don't want the hole for the deadbolt to have a ton of wiggle room (because that will make it easier to kick open the door). So, this project was put on the back-burner because there were a lot of "gotchas" that I didn't really feel like spending the time/effort/money into investigating solutions. Maybe one day when I have something I want to lock just for fun.
Around the same time as companies began releasing "home automation" devices, I wanted to create a bank of LEDs, and control it without having to cut through walls to bring wiring to the switch on the wall. Of course, there were already plenty of products on the market that already did this, but it was a fun experiment.
I downloaded the APIs for the XBee framework, did a ton of research, bought the wireless radios, and a couple Arduino boards. This project never really got past the prototyping phase because of life.
You might also be interested in the other Arduino projects on here. Feel free to poke around other articles.
This is an Arduino project I created a few years ago. The idea was to build a stop light so my mom knew when to stop pulling into the garage. I made three versions of it. Version one was just a prototype, nothing fancy. All of the versions did have a switch as a master on/off.
Version two had three relays (one for each color: red, green, blue). There were 6 rows of RGB LEDs, with 5 LEDs per row; totaling 30 LEDs. If I remember correctly, these were common cathode LEDs, but it's been a while. I wish I had cataloged what parts I used better so I wouldn't have to redo the math all over again.
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