Portable 120V to 240V Converter; or How to Fast Charge at Your In-Law’s House | Lrd12 Overload Relay

I use a contactor with my sonoff, 1kw pool pump. The sonoff is seriously under specced for switching a pool motor.

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Historically, there were two post-war electric utilities, and one contracted with GE for equipment, and the other contracted with Siemens – thus the two wound up with different frequencies.

Oh, and if you want a car charging hack, there’s always the Hydra: http://hackaday.io/project/3939-j1772-hydra

Think for a minute, what are you going to find inside that box? You need to consider what voltages it takes as a power supply, what it does with those voltages, where any hazardous voltages might lie inside it, and whether or not they are likely to be accessible once the cover is off. It’s important to realise that simply because an item isn’t mains-powered does not mean you no longer have to consider this, for example if you’ve ever opened a camera with a built-in flash you may have encountered a capacitor with several hundred volts remaining on it. Where is the high voltage going to be?

Stripping wire with my teeth (my front teeth have a perfect gap at the bottom for it, I could probably specify them in AWG) to fit the socket onto a phone extension cable. While rather stupidly forgetting I’d plugged the damn thing in downstairs. Yowch! Fortunately it wasn’t ringing. As a mistake, it was educational.

Step 4:  Use the V-I curve (Fig. 3) in the MOV’s datasheet to verify that leak voltage will be less than the 300-V ceiling.

MOVs tend to degrade gradually after a large surge or multiple small surges. This degradation leads to increasing MOV leakage current; in turn, this raises the MOV’s temperature, even under normal conditions such as a 120-V ac or 240-V ac operating voltage. A thermal disconnect adjacent to the MOV (Fig. 4) can be used to sense the increase in MOV temperature while it continues to degrade to its end-of-life condition. At this point, the thermal disconnect will open the circuit, removing the degraded MOV from the circuit and thus preventing potential catastrophic failure.

User interface. Sony has retained a similar menu system in the Sony A33 to that previously featured in the Alpha series DSLRs, but incorporating the new database-driven Playback mode from the NEX-series SLD models. The user interface of the Sony A33 is generally clean and easy to understand, with the one major exception being the rather arbitrary segregation of still images and videos in playback mode. Switching between viewing stills and videos requires the user to either enter the menu system, or zoom out to the thumbnail view and select the appropriate tab. Neither option is immediately obvious without reading the manual, and photographers unfamiliar with the interface might believe they’d accidentally deleted the unavailable media, not realizing they were simply in the wrong viewing mode.

Even with a large heat sink like that, shrink it to 50mmx100mm and the datasheet lists a max of 10A. With that aluminum plate, I’d be surprised if it could handle more than 5A for a length of time.

A steamy day on the flat roof of a building will let you feel how many inches the 480 can sting your fingers from also.

We’re pleased to report that the EVF in the Sony A33 provides better dynamic range than most, and does a decent job of preserving highlight detail in high-contrast scenes. The slight distraction caused by the "rainbow" effect is relatively easy to ignore most of the time. Sony specs the EVF as having 1,440,000 dots, of which 1,152,000 are effective in the viewfinder display. We believe that the company is following precedent here, by reporting a dot count as if each pixel constituted three separate color dots, rather than being time-multiplexed. If that’s the case, the actual pixel resolution would be 480,000 total pixels, of which 384,000 are effective in the final image.