Background

Q: How do you hack a high-tech tea maker?

A: Through the power line.

The full write-up and video is on Hackster. Check out the project on Hackster.io

Power Monitoring

This is what the power signature looks like when brewing tea. It's pretty clear when the power usage jumps straight up. That's the resistive heating element in the base kicking on. You see it turn off, then the basket motor turns on. After a few minutes, you see a tiny rectangular blip. That's the motor raising the tea basket back up after brewing. This is what I trigger off of to play the WAV file.

I captured the power usage with this rig I borrowed from work. It helps when you work at an electrical power monitoring company and are friendly with the support engineers.

Circuit Build

The prototype circuit

The AC power + transducer setup. It's pretty easy to make. You just take a 15 Amp appliance cable and cut it, slip the transducer on the hot line, and re-crimp the lines.

The final circuit for the project. I used two Arduinos: one to play the WAV file and one to sample the power and monitor the state of the tea maker. They communicate over a simple serial protocol.

Action Shots!

Complete and working. You know it's working because the LED light is on. =) Watch the video to see the thing in action.