“Let rise at room temperature” is a common instruction in bread recipes, with “room temperature” being about 70 F (21.1 C)*. For various reasons, however, this temperature can be hard to find in my apartment in Berkeley, California, and so my bread doughs sometimes rise far too slowly.
One day, I realized that my Arduino Uno microcontroller could help solve this problem. I had earlier configured it to measure milk temperature during yogurt making, and realized that would be a short leap to use it to control the air temperature inside a container, thereby creating a stable and warm location for dough fermentation and proofing (a “proofing box”). My idea was simple: an incandescent light bulb in a clip-on lamp as the heat source, a temperature sensor, a switch that turns the light bulb on and off, and the Arduino to control the switch. Basically, as one person who heard my plan put it, “It’s an Easy-Bake Oven!”
But how would I switch the light bulb on and off using the low voltage, low current digital outputs on the Arduino? A relay could be wired in and the lamp could be hacked, but that would be bothersome and potentially dangerous. Then I learned about the Powerswitch Tail II. This easy-to-use device allows your Arduino or other controller to switch on and off an A/C powered device, like a lamp, coffee maker, hot plate, and so on. By connecting a digital output line and ground from the Arduino to the + and – inputs of the Powerswitch Tail, the connected device can be switched on and off. No cutting, soldering or taping required, just connect and go…..
Featured Adafruit Product!
Powerswitch tail 2: The Power Switch Tail II is a smart alternative to slicing apart power cords to wire up your own relays. Its a compact 120V 3-pronged extension cord, with a relay board embedded in the middle. Connect to the relay using two screw terminals and activate by providing a 3 to 12V signal (3mA current draw at 3V, 30mA at 12V). The relay can switch 15 Amp resistive loads such as heaters, small skillets, lights, etc. An LED indicator above the terminals will help you with debugging. (read more)