Select the Right Varistors for Overvoltage Circuit Protection | Circuit Breaker Parts

I flashed Tasmota firmware onto the Sonoff, and configured GPIO2 as a counter, and I now have the whole setup reporting to Node Red, which switches the pumps on and off on schedule, or as desired. I’m quite chuffed with the result, although now I need to learn a lot more about how Node Red works!

I couldn’t even find a de-rating chart or graph online for this relay. Also, many SSRs (and other devices) do not recommend the “bottom” orientation for heat sinks.

Bryan Orr is an HVAC and electrical contractor in Orlando, Florida. He is the founder of HVACRSchool.com and the HVAC School Podcast. He has been involved in technician training for 15 years. 

I do not disagree that this is not the best way to do it. I have only used it for temporary installation, and only when I can frequently inspect everything involved for signs of elevated temperature. At home, I had a licensed electrician install a NEMA 6-50 and a 40A circuit (which we de-rate to 32A for EVSE service) in our garage for our car charging needs.

Most systems now do not distribute ground (earth) from the MV / LV substation. At the sub the neutral is connected to ground through a low value resistor (<1 ohm) to a nest of earth spikes. Live and neutral are then distributed. At the house Neutral will be connected to a suitable ground point and at that point the earth connection is split off from the neutral. This means that any difference in ground potential is slowly leaked through the big resistor at the substation and it is a big resistor, looks like an oil tank maybe 2 metres high and 1.5 metres across. It is also normal that if there is any equipment at a pole it will also have an earth nest for the neutral wire.

In case you hadn’t noticed, 2010 is the Year of 3D in the HDTV space, and all the television makers are rushing to add 3D capability across their product lines. Sony has come up with a clever way of capturing 3D images using the same "sweep" technology as in their normal 2D panoramas. As the camera is swept across a scene, it will naturally see various parts of the subject from slightly different angles at different points along its sweep. Sony’s engineers have taken advantage of this to add a 3D Sweep Panorama mode to a number of their cameras, the A33 and A55 included. While the 3D data is apparently stored in a fairly standard file format, viewing the 3D images currently requires connecting the camera’s HDMI output to a Sony 3D-capable television set. Sony’s promised 3D Sweep Panorama playback support for their PS3 game consoles, supposedly coming as early as this September. That’s still a bit limiting, but hopefully as 3D technology matures, various manufacturers will be able to read each others’ 3D formats.

The first was working with a bench buddy on a military SSB Shortwave amp. My bench buddy assured me he had powered the system down and unplugged everything necessary, and I trusted him. I reached in with a pair of needle nose pliers to remove the plate voltage supply on the amp tube, and got hit by 26kv DC. Shouted and was teleported backwards about 3 feet, but no damage done (except a small melted bit on the end of the pliers).

When I was a about 12, my mother decided to fault find a 35mm slide viewer. 240vac in, 6vac out of the transformer to a plug which fitted a socket under the viewer. Slide closed two metal contacts.

I can’t speak for the Model 3 since I don’t know anyone who owns one yet, and Tesla has removed charging rates at 110 volts from their distance calculator.

Once upon a long ago I was tuning a Tesla coil I’ve built with a friend. The coil was driven by a dirty cheap spark gap made with a screw that had to be rotated to change the distance between electrodes. I had to switch off the 6kV primary transformer, ground the terminals and rotate the spark gap, repeating this procedure until the biggest possible spark jumped out of the coil. After repeating it many times, I accidentally forgot one step. I’ll never forget that moment. My arm was thrown in the direction of the wall as if it had its own will and wanted to get through. Not good. Very painful.

Given my long-term dislike of EVFs, I was surprised to find myself as comfortable as I was with the one on the Sony A55 and A33. It by no means corrects all the ills of the genre, but does go a long way in the right direction. It still loses highlight detail in scenes with both deep shadows and strong highlights, but I found it workable most of the time. I could generally make out clouds against the sky, important for framing landscape shots. It also seemed to do pretty well under low light conditions, although as of this writing, I haven’t done a lot of night photography with the camera. Still, the large pixels of the Sony A33′s APS-C size sensor mean that its EVF is much more able to form a usable viewfinder image under dim lighting than is that of a typical digicam. Under really dark conditions, I’d still like to see it gain-up a bit more, though, even at the cost of slower refresh rates.

Regular gasoline costs about $3 per gallon where I live, so it’ll cost (26 / 46 * 3) = $1.70 to propel the Niro the next 26 miles after the battery is depleted.