More people watched the Logan Paul vs. KSI fight on Twitch than on YouTube | 19mm Momentary Push Button

The very first point to make clear when writing an article like this one is that you should disregard any ideas of “safe” voltages or currents. While the story about some significant number of people who die every year from licking a 9-volt battery is probably an urban legend and you have little to worry about from low voltage equipment, it is best to look at any higher voltages as potentially dangerous and react accordingly.

Last year, Sonos announced plans to add support for Apple’s AirPlay 2 to its speakers. AirPlay 2 is a significant feature in that it will allow iPhone and iPad users to send audio from basically any app to Sonos’ great-sounding speakers. And you’ll be able to tell Siri to play tracks from Apple Music on Sonos systems; the Sonos One smart speaker doesn’t currently let you launch music from Apple’s service with voice commands, but AirPlay 2 is a roundabout way of introducing that convenience. The difference is that you’ll be doing the talking to your phone instead of the Sonos.

“180 bolts per second”? Now there’s an engineering unit I’ve never encountered in more then 50 years. No, it’s just a 150-180 volt sinusoidal or square wave at various frequencies. In past years, the coil on the bell was mated to an appropriate capacitor to allow ringing a specific phone on a “party line” based on the ring frequency. It was amazing stuff for a time when they simply hadn’t run enough wires for all of the individual “private lines”, so they had to engineer very basic things to fill the need. It was in a sense, the most basic and pure form of understanding the physics (electrical and mechanical) hacking.

Very nice. It’s similar to my Toast-R-Reflow power board (though that one has two channels and uses BTA-20s).

My first thought was that the terminals were over torqued rotating the blocks, stretching the pins, and tearing the pads.

It’s not that simple according to National Electrical Code (NEC) NFPA 70 for several reasons. Here are some additional factors to be considered:

I think Brian’s point was that if the bond between the earth ground and the neutral return of the incoming premises power isn’t good enough, then the short to earth might *not* trip the breaker. Of course, it would likely start a fire instead (the resistance may not be zero, but it will be low enough to sink a great deal of power in most cases and a 15A breaker will tolerate a couple THOUSAND watts), but I think that if you can’t trust that the building is to code, then all bets are off.

The number on this photo is a little misleading. 337 mpg! I think I shot it after having the car for about ten minutes, nearly all of it without using the petrol engine. Still, it’s a nice little tease for any friends riding along.

I used a bridge rectifier from a stick welder, it takes 120vac down to 63vdc with no load. Out put it into a pair of MWT primary coils in parallel. Just like this one. Works but draws too much current. The field strength is around 300 pounds. The coil resistance is about 3 ohms, and draws around 20 amps.

i have 300w 12v silicon heat bed i just use a 700w pc power supply and 70A relay it heats bed over 100 oC in about a minute no problem

WIRE CONTACTOR: A wire and contactor displaying the 90°C rating on the wire and 75°C rating on the contactor (when properly torqued).

If you had the choice between two identical-looking boards, with the same pictures, and review ratings, would you spend an extra 20¢ on the more expensive one? That twenty cents really adds up, you know- if I was buying 1,000 ESP-12 boards, for example, that would be two hundred dollars saved, and you would be pretty happy with yourself. That is, if it works. Otherwise, you feel really dumb.