CMOS logic directly powered from mains

In countries with non-polarized plugs, this is not an issue, since about half of the devices are plugged in one way and the rest the other way, thus loading both half cycles.

In the tube era in Europe, TV sets were AC/DC with only a half wave rectifier for the anode voltage, in practice there was no problems thanks to the non-polarized plugs. Of course, the TV set design was a bit of a problem, with the TV-chassis either at the Neutral potential or full 220 or 240 Vac mains potential, requiring good insulation and external signal connectors were rare. ,

Show your math.

Who cares? Consumers are only charged for real power. If it's good for the grid, so much the better.

A billion nightlights on a block might cause a problem, sure.

Who cares?

I don't remember which Brit it was, here, but I liked his term "anti-parallel".

My longer strings are wired "anti-parallel". The shorter ones obviously have a diode across the string.

I don't think I ever saw a valve era universal set with good insulation. The grub screws in the knobs were always an issue - users really learnt what electricity & water don't mix meant.

NT

see you in ~30days. RL

I thought that it was NA that was the slowest to polarize their wall connection hardware...and these things are all going to be mounted the same way, per polarized pins and user-identified 'up', in the current market. Some users will even be frustrated, in that their wall socket hardware forces the things to be 'upside-down'.

In any event, where it matters, capacitive loading is actually discouraged. Where displacement power factor is actively compensated, they rarely allow it closer than 0.92, due to the threat of low-load or sudden disconnect transients. Not likely a concern on dedicated residential lines.

RL

Yes, 'anti-parallel,' --+------. | | | --- V ~> ^ ~> --- | | | --+------'

I've called that 'back-to-back' forever, using the same term for inverse series zeners. I never thought it confusing, since inverse series LEDs would make no sense, however, 'anti-parallel' is perhaps better, as it avoids any possibility of confusion.

Cheers, James Arthur

I should compute the cost per lemon-KWH.

LOL!

I've never seen a residential outlet installed (at least by an electrician) pin-up. OTOH, IBM had a rule that they had to be pin-up so that any metal falling would hit the pin first. At my CPoE, the outlets are all sideways. ;-)

Not worth worrying about, particularly for a nightlight.

Wow! The tough guy can't stand a little disagreement. Must be a millennial.

That seems to raise issues similar to those in the other thread - during a transient, the varistor takes some of the voltage, and the 100 ohm resistor takes the rest, which could well be outside its specification unless it is a special type.

Sylvia.

Mains waveform distortion can result in greatly increased resistor P_diss, so it should always be a fusible type. That circuit is a bit more complex than is usual.

NT

A fusible type will fuse where necessary, but that's not the problem here. The question is what happens when 4kV or so is put across the 100 ohm resistor for a few microseconds.

Sylvia.

I don't know many mains appliances that would cope with that.

NT