New Google Classroom update makes it harder to cheat on quizzes | 25 Amp Circuit Breaker

I don’t know if the heat is high enough but mirror heating pads can be quite small and put under a sheet of glass would be quite effective.

well, originally they were 2 kW transformers (or at least from microwaves that are rated to 2-2.5 kW), and on secondary is wounder stranded thick wire (diametar around 7-8mm)… enought power to melt nails with 3-4 mm diametar…

If you can power the logic side with some +5V derived from mains, there is no point keeping the optocouplers, right? Of course, the ESP would need to be programmed when unplugged from mains A/C, but with OTA, it should be possible to control it all wirelessly once the initial firmware setup is done, even more so with LUA where telnet over wifi can be used once initial setup is done. So now, what kind of circuitry is needed to hash mains A/C to +5V DC (or even better, directly +3.3V)? What’s in a commercial USB adapter? Greg

Ah, right you are. I’m out of date — I last dealt with UK power in 1981, and have not been back since. Thanks for the update.

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If you insure that your HV and LV systems are completely separate, and joined only by UL registered galvanically isolating components, only then can you be prepared to say that the logic portion of your system is safe. And doing that maybe won’t make fewer things capable of going wrong, but at least fewer things capable of spectacularly dangerous failure.

Generally, most LED power supplies are a constant-current type, and are often referred to as LED drivers. These can be purchased as off-the-shelf assemblies containing MOVs to meet lower-level surge requirements.

Turn off the power at the main box to the A/C unit and open the electrical access panel on the air conditioner. It is usually located where the electrical power comes into the unit. Check for rodent nests and wires that have been chewed or frayed.

Please nobody get one of these boards. It is not a safe design for working with mains voltages. This guy has not followed guidelines for minimum creepage and clearances between the low voltage and mains side. You think it’s optoisolated and it may work fine for the majority of the time, but as soon as a mains voltage spike comes along it could bridge the gap and zap your circuit and you if you’re touching it (and your computer if you’re doing doing dev work at the time).

In their best days (unfortunately behind them), they have merely LISTED an appliance. (Listing is currently their TOUGHEST CRITERION).

Specs-wise, the Mi Mix 3 moves the series to OLED with a 6.4-inch 1080p panel. There are four cameras in total: 12-megapixel wide-angle and telephoto modules on the back, and a 24-megapixel selfie camera backed by a 2-megapixel sensor on the front. The phone has a fingerprint sensor on the back, so unlike the Oppo Find X you don’t have to pop the cameras up every time you want to unlock it.

I agree. Plus, from my experience using remote controlled outlets, when the 4A inbuilt fuse dies because of reasons, the relay stays intact. O the other hand, I have never seen a light dimmer with blown fuse, just blown triacs.