mains power

9 Articles

Awesome Prank Or Circuit-Breaker Tester?

January 31, 2017 by 54 Comments

Many tools can be used either for good or for evil — it just depends on the person flipping the switch. (And their current level of mischievousness.) We’re giving [Callan] the benefit of the doubt here and assuming that he built his remote-controlled Residual Current Device (RDC) tripper for the purpose of testing the safety of the wiring in his own home. On the other hand, he does mention using it to shut off all the power in his house during an “unrelated countdown at a party”. See? Good and evil.

An RCD (or GFCI in the States) is a kind of circuit breaker that trips when the amount of current in the hot and neutral mains power lines aren’t equal and opposite, which would suggest that the juice was leaking out somewhere, hopefully not through someone. They only take a few milliamps of imbalance to blow so that nobody gets hurt. Making a device to test an RCD is easy; a resistor between hot and the protective ground circuit would do.

[Callan] over-engineers. He used a 50 W resistor where 30 W would do under the worst circumstances. A stealthy solid-state relay switches the resistor in, driven by an Uno and a Bluetooth module, so he can trip his circuit breakers from his smartphone, naturally.
Continue reading “Awesome Prank Or Circuit-Breaker Tester?” →

Wake Up With A NeoPixel Sunrise Alarm Clock

August 11, 2016 by 7 Comments

Like many of us, [Lee] wakes up every morning grumpy and tired. Once he decided to try to do something about it, he settled on making a sunrise alarm clock using NeoPixels. Over the course of thirty minutes the clock illuminates 60 NeoPixels one by one in blue mode to simulate a sunrise.

The clock has three modes: 30-minute sunrise, analog time display, and a seconds counter that uses the full RGB range of the LEDs to light up one for each passing second. It runs on an Arduino Pro Mini knockoff and an RTC module for the sake of simplicity. [Lee] chained NeoPixel strips together in five rows of eight, which allowed him to use a 3×5 font to display the time. The only other electronics are passives to protect the LEDs.

NeoPixels are great, but powering them becomes an issue pretty quickly. [Lee] did the math and figured that he would need 3.4 A to drive everything. He found a 3-outlet USB power adapter that delivers 3.4 A total while shopping at IKEA for an enclosure. [Lee] took his first Instructable from beginner to intermediate level by cracking the adapter open and using two of the USB ports wired in parallel to provide 5 V at 3.4 A. [Lee] has the code available along with detailed instructions for replicating this build. Be sure to check out the demo after the break.

We love a good clock build around here, especially when they involve Blinkenlights. For those less interested in building an alarm clock, here’s a word clock that pulls time and weather data with an ESP8266.

Continue reading “Wake Up With A NeoPixel Sunrise Alarm Clock” →