Building USB-Controlled Lights

Dec 03, 2013

A breadboard, some solder, a few broken pins, 4 notebook pages, and some number of hours later, I've finally finished making my first USB-controlled circuit!

The controlling program is written in Java and uses jSSC as the virtual COM port interface.

A pin on the microcontroller has been set to a 6 MHz clock , and is "AND"ed with the "data available" pin to signal the fetching of the next instruction from the Java program.

Unfortunately, I didn't have any actual AND gates, but a NAND-Inverter combo did the trick. That's how they're made anyway, right?


A "scale up" circuit (as I'm calling it) goes from a 3.3V logic signal, to a 5V N-Channel MOSFET-driven supply voltage, to a relay-controlled 120V AC switch. This relay connects to a standard wall outlet, allowing any electrical device (up to 6A) to be remotely switched on and off!

outlet Remotely controlled outlet

outlet Relay junction box

And now it's time for a demo video so you can see what all of this means:

(If you still don't get it, picture this: remote-controlled Christmas lights!)

This blog post is from "The Vault". It was migrated from an older version of

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