New Google Classroom update makes it harder to cheat on quizzes | 220v Contactor Relay

I like the idea, but you don’t need a 3D printer for this. Just use conductive strips or good ol’ fashioned wire.

You can not do it much more complicated! If you want to heat your print bed by induction, it has to be ferromagnetic to work with a commercial induction cookers coil. And using the copper coil as resistive heater is also no good idea.

Not to be argumentative, but please show me a case in which a H/O policy denied coverage for a fire loss because the homeowner used a non-UL listed device. H/O policies are contracts, strictly regulated by each state’s insurance department. The vast majority of H/O policies are “All Risk” based, meaning that you are covered for everything unless there is a specific exclusion for it. I have read many times on this forum and others about H/O policies not covering such claims, please show me ONE that actually is true. There may be one out there, but I have never seen it.

Two inputs for the beefy converter are supplied from outlets not just on separate circuits, but on two circuits whose hot lines are 180 degrees out of phase. That means identifying where there are two plugs, not protected by GFCI outlets or breakers, which are on two separate hot lines of split phase power. To protect the user, [Nick] designed in a set of relays which kill the circuit when one of the two supplies is unplugged. A system that didn’t have these protections would have mains voltage on the prongs of the disconnected plug.

The Sony A33 includes an internal stereo microphone, actually comprising two separate monaural microphones located on either side of the electronic viewfinder / flash housing. It can also accept external stereo microphones, courtesy of a 3.5mm jack on the left side of the camera body. Alternatively, sound recording in videos can be disabled, if preferred. The built-in speaker in the Sony A33 is monaural, and there’s no manual control over audio recording levels.

GM quickly realized this and changed the default to 8 A charging to prevent fires, and many others limit at 10 or 11 A.

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The second was in an industrial setting, working on repairing a 480v-supplied welder in a hard-wired installation. Plant electrician assured me the circuit was locked & tagged out. I trusted him. Sprayed some contact cleaner on the mains relay to start, and took 480v up the spray and into the can (and my hands holding it). That was an unusual sensation.

This makes no sense when you’re designing a heater. The higher the current, the hotter the wire will be. That’s why power companies transmit power at high voltage in the first place: they want to minimize heating. 120 watts flowing through a wire does NOT mean that 120 watts of heat are dissipated in it. You’ll get a much more efficient heater at lower voltages and higher currents.

I don’t know about anywhere else, but in North America, power enters the home via two 120V hot and one neutral. The two 120V hot legs are out of phase with each other, and when combined, you get 240V. So, from the breaker panel, you can pull 120V or 240V, depending on the type of breaker you insert at a given position. Some large appliances (water heaters, central AC units, electric stoves, large power tools) are 240V in North America, but most everything else is designed for a single leg 120V feed. Then just to make things even more complicated, large industrial businesses often have three phase 480V for the really big equipment.

I had my poke. Mostly people saying “may” or “could” invalidate your insurance and advising caution. Which is sensible enough. Also mention of laws mandating a professional installing things like new wiring for cookers, and other kitchen / bathroom stuff. Makes sense since there’s water about. This is the UK that I looked up, since that’s where I live. Our electrical standards are pretty high, mandatory ring mains, limits on spurs and wiring length, and even our mains plugs have half a dozen safety features built in (protection against the agony of accidentally stepping on one not included).

You now have a Tesla 3 correct? What is the efficiency hit by using 120 volts? It used to be a 30% hit for the S,X, Roadster, and new Rav4Ev with the Tesla drivetrain, Meanwhile 12 amps at 115 for a VOLT is quite efficient.