RF switching module can learn new remotes


This breadboarded circuit is [Sergio’s] solution to controlling appliances wirelessly. Specifically he wanted a way to turn his pool pump on and off from inside the house. Since he had most of the parts on hand he decided to build a solution himself. What he ended up with is an RF base station that can learn to take commands from different remote devices.

The main components include the solid state relay at the bottom of the image. This lets the ATtiny13 switch mains voltage appliances. The microcontroller (on the copper clad square at the center of the breadboard) interfaces with the green radio frequency board to its left. On the right is a single leaf switch. This acts as the input. A quick click will toggle the relay, but a three-second press puts the device in learning mode. [Sergio] can then press a button on an RF remote and the device will store the received code in EEPROM. As you can see in the clip after the break, he even included a way to forget a remote code.

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FireHero: Raspberry Pi Controlled Pyrotechnics

Fire Hero 3

To put on a live pyrotechnic show at a music festival, [Chris] built the FireHero 3. The result is remotely controlled flames shooting up to 100 feet in the air.

The system is controlled by a Raspberry Pi and an Arduino. A server runs on the Pi and allows a remote computer to control the system. The Pi sends commands over serial to the Arduino, which switches solid state relays that actuate the valves.

There’s also some built in safety features: the system won’t boot unless you have the right key and RFID tag, and there are pressure transducers and temperature sensors to ensure the system is operating safely. A CO2 actuated valve can quickly stop fuel flow in an emergency.

Vaporized propane creates the fireballs. The vapor is created by heating the supply tank in a hot water bath. An accumulation tank stores the vapor and custom built manifolds distribute it to the various flame cannons. At each cannon, a silicon nitride hot surface igniter (HSI) is used to ignite the flames once the valve is opened.

After the break, watch a video the the FireHero making some flames.

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Mains rated solid state relay test box


We like our nice, safe, 5V prototyping projects where the only thing that might get fried is a chip. But there are times when you want to switch appliances for one reason or another and then you’re going to want a mains rated relay. [Viktor] got tired of having exposed high voltage on the bench during the prototyping stage of these projects so he recently built a solid state relay test box.

The only thing he bought for the project was the SSR itself. To act as an enclosure he used the brick from an old laptop power supply. This is perfect for a couple of reasons. First off, it’s designed to contain high voltage if there is ever a short or other problem. Second, it’s already setup for incoming and outgoing power. He just needed to remove the guts and mount the relay. Notice that it comes with a clear plastic shield that physically separates the high voltage side from the low voltage control end. This, along with the cable routing, keeps the dangerous stuff on one side to ensure you won’t get an arc to the low voltage portion of the project.

Building a better PID smoker controller

[Matt] wanted to have more control over his meat smoker so he built this advanced PID smoker controller. It uses the solid state relay seen in the bottom-right of this image to switch the smoker’s heating element. But all of the other goodies that are included add several features not usually found in these builds.

This is a replacement for the commercial PID unit he used on the original build. That monitored the temperature in the smoker, using predictive algorithms to maintain just the right heat level. But this time around [Matt] is looking for extra feedback with a second sensor to monitor meat temperature. Using an Arduino with an SD shield he is able to data log the smoking sessions, and his custom code allows him to specify temperature profiles for resting the meat after it has hit the target temperature. It kind of reminds us of a reflow oven controller… but for food.

Spaduino heats up a used hot-tub

[Ryan] and the roomies decided that a hot tub was just what they needed to spice up the place. They hit Craig’s List and found one for the right price. After acquisition and setup they were pleased to find that the jets and pump worked great. But you’re not going to want to stick as much as your big toe into this ice-cold cryogenics experiment. Some poking around in the control system exposed the dead relays which are responsible for switching the heater. Instead of swapping the parts, [Ryan] began building a control system that will replace the twenty-year-old original.

The heating element still works, but it’s rated at 5.5 kW and here’s no way to automatically switch it on and off. [Ryan] found a 60 Amp solid state relay which can handle the load, and plays nicely with his Arduino. Initial tests got the tub up and running again. Obviously you want the tub to maintain temperature and so a thermistor was added to take readings from the heater core. There’s also a potentiometer to adjust the temperature, and an LCD screen to show the current settings. But [Ryan] hopes to add more features over time, like incorporating jet control, and adding wireless communications via an Xbee module.

Replacement refrigerator controller

[Michael] got his hands on a refrigerator that he intended to store beer in but found that it ran constantly. Instead of buying a new thermostat he and his friend [Doug] set out to build an Arduino-based controller for the fridge.

The finished project will switch 240v so they’ve used a transformer to power the logic circuitry and a solid state relay to handle the load switching, with a Dallas 1820 for temperature data. Because the Arduino offers more capabilities than the average thermostat hack they also decided to tap into its potential by adding an Ethernet shield. We see the Arduino as a prototyping device and so do these folks. Once the bugs in their first PCB prototype are worked out the circuit will use the ATmega328 and do away with the Arduino.

[via @littlebirdceo]

X-mas Hack: 8-channel musical show

We’ve been seeing them appear one house at a time over the last few weeks as Christmas lights are making their annual appearance. Some folks just throw a set of net-style lights on the bushes and call it good but that wouldn’t suit [Noel]. He’s outfitted his house with a show that includes music, 8 controllable light channels, and an Internet interface.

He’s used a plastic toolbox as an enclosure to house everything. Affixed to the base of the enclosure are eight solid state relays for the strings of lights. An Arduino is used to control the SSR switching, playback music through an FM transmitter, and to interface with the wireless bridge.

Rubberneckers can tune their radio to the broadcast frequency and log into the web interface to request their favorite tune or track Santa’s current location. The device even implements VU monitoring to sync the light show with the music. If you want more, watch the video after the break or check out his step-by-step instructions. The Arduino library sure makes the code pulling this all together pretty simple!

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