115 V car outlets

A good story deserves at least one beer during the telling, don't settle for less.. :^)

George H.

How was the resistor a problem?

The voltage on the cap would not be 170 volts. That would be the peak voltage on a sine wave. This is a square wave with a minimal off time at zero volts. So the cap voltage is likely 120.

"modified sine" is not a square wave, exactly, it's 1/3 pos, 1/3 zero and 1/3 neg. If the pos and neg HV are 170V, then the rms voltage will be 120V, see the referenced AoE-III discussion and scope traces.

This means that heating and similar applications will be happy, with 120Vrms. And with 165V peak, about the same as a 120V sine wave, rectifier- bulk-cap power supplies will also be happy. They'd be decidedly unhappy with only 120V peak.

I get about 139 volts for RMS of the modified cycle you describe when powered from 170 VDC. I assume the 1/3 duty cycle is just approximate?

I don't see a discussion reference.

Look at it this way: the positive half cycle is 1/2 on and 1/2 off. By symmetry, so is the negative half cycle. The duty of the positive half cycle is 1/2. The RMS is sqrt(1/2) ~ .707 and when multiplied by 170V you get 120V.

Cheers.

ctrl + leftclick on netname in waveform viewer to get RMS

Version 4 SHEET 1 880 680 WIRE 224 -400 0 -400 WIRE 0 -368 0 -400 WIRE 0 -272 0 -288 WIRE 224 -272 224 -400 WIRE 0 -176 0 -192 WIRE 224 -96 0 -96 WIRE 0 -64 0 -96 WIRE 0 32 0 16 WIRE 224 32 224 -96 WIRE 0 128 0 112 WIRE 224 176 0 176 WIRE 0 192 0 176 WIRE 224 192 224 176 WIRE 0 288 0 272 FLAG 0 128 0 FLAG 0 288 0 FLAG 224 112 0 FLAG 224 272 0 FLAG 0 -176 0 FLAG 224 -192 0 SYMBOL res 208 16 R0 SYMATTR InstName R1 SYMATTR Value 1 SYMBOL res 208 176 R0 SYMATTR InstName R2 SYMATTR Value 1 SYMBOL voltage 0 176 R0 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName V1 SYMATTR Value SINE(0 170 50) SYMBOL voltage 0 16 R0 WINDOW 3 -492 58 Left 2 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName V2 SYMATTR Value PULSE(0 170 2.5m 1u 1u 5m 20m) SYMBOL voltage 0 -80 R0 WINDOW 3 -487 54 Left 2 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName V3 SYMATTR Value PULSE(0 -170 12.5m 1u 1u 5m 20m) SYMBOL res 208 -288 R0 SYMATTR InstName R3 SYMATTR Value 1 SYMBOL voltage 0 -288 R0 WINDOW 3 -492 58 Left 2 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName V4 SYMATTR Value PULSE(0 120 0 1u 1u 10m 20m) SYMBOL voltage 0 -384 R0 WINDOW 3 -487 54 Left 2 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName V5 SYMATTR Value PULSE(0 -120 10m 1u 1u 10m 20m) TEXT -34 312 Left 2 !.tran .1

See above, "see waveforms and math in AoE-III, page 673"

I looked it up, to refresh my memory, and I'm sorry, the "modified sine" is 1/4 pos, 1/4 zero, 1/4 neg, 1/4 zero. That's exact and you'll see that works fine. There's a simple math derivation in the reference.

On Tue, 26 May 2015 07:01:17 -0700 (PDT), George Herold Gave us:

I play the online pool game by Miniclip.. My persona (nym) in there is "An Ale-ion"

I am a few levels away from becoming a "Pool God".

I win and the person thinks "I just got beat by an ale-ion!"

So you're saying, PFC is indeed *even worse*? :-)

If the trip time is ~microseconds, that teeny delta-V charging the caps after the dead time will be more than enough to push it over the threshold!

Could be, too. Who knows how they rate them... Sears watts?

Yeah, peak power, at 0.1 power factor, maybe. :-)

Tim

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I don't know about your Dell laptop, but most new Dell laptops (and their s upplies) have the "center" capacity pin. It is a 1-wire data pin that tell s the laptop the power/current capacity of the supply. If you don't have t he data pin, the laptop will say something like "plugged in, not charging." So whether it is an AC-DC or DC-DC converter, it needs the capacity/data wire for full functionality.

BTW, does anyone know much about these 1-wire data chips that are in the De ll supply? (Or "how do I make my own." lol)

HP has a center capacity wire too, but it seems less finicky than the Dell laptops.

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supplies) have the "center" capacity pin. It is a 1-wire data pin that te lls the laptop the power/current capacity of the supply. If you don't have the data pin, the laptop will say something like "plugged in, not charging ." So whether it is an AC-DC or DC-DC converter, it needs the capacity/dat a wire for full functionality.

Dell supply? (Or "how do I make my own." lol)

Apparently it is just a 1k maxim one-wire memory, I guess you can make your own if you know what to put in it

now that it's been agreed that cell phone should charge via USB, Dell shoul d get with the program and do like everyone else, ~19V and a regular barrel connector

-Lasse

Apparently, the newer ThinkPads moved from round to rectangular connectors... doesn't look like they added any new meat on the thing to justify its 200W capacity, let alone the complete incompatiblity with literally every adapter in the office.

Tim

Not just Dell. My Lenovo uses a rectangular connector with three contact so it can "talk" to the PC and complain when I use one that is not the full 135 watt rating. Otherwise it works as long as it doesn't need to charge the battery, but the pop up dialogs are impossible to deal with every 2 minutes. So if I want a spare power pack it is over $100.

That connector allows them to use a 1 wire connection between the PC and the "smart" power pack. Mine is rated for 135 watts and costs about $135 to replace. When I was looking at buying the laptop I tried to price a power pack and Lenovo said they didn't have a recommended replacement unit yet. lol It was only a couple of months *after* I bought it I found they were so expensive.

Those aren't the numbers given above, 1/3, 1/3 and 1/3. So it is 1/4,

Yes, others seem to be explaining that.

I don't have AoE so the reference does me no good. Thanks anyway.

The four pieces: pos, zero, neg, zero for "modified sine" are easily remembered by realizing there are equal zero times between each of the pos and neg portions. Maybe I had better say, should be easily remembered, because I myself forgot, even tho I wrote that section in our book! Actually, more accurately, I failed just now to visually draw out more than a cycle of the waveform. Doing that reveals why the 4th zero is needed.

The scheme is particularly cute when you realize that a 240Hz (200Hz) oscillator and a dual flip-flop generates the H-bridge switch drive for a 60Hz (50Hz) output, and it accurately fulfills both the peak and rms criteria.

But other, more complex, waveforms can do a better job of zeroing out high-order harmonics.

Hah, that can be easily remedied!

a cheap power meter puts the efficinecy and power factor at over 90% on mains, I have not tried when powered by the inverter, but don't expect it to differ radically.