just call it 2 phase

There were photos of some multiphase mecrury vapor recitifers from a subway line on alt.binaries.pictures.radio a few years ago.

Reply to
Michael A. Terrell
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This is the site I was thinking of

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Reply to
James Sweet

| A lot of transformerless tube radios were sold as AC/DC, and wouldn't | have worked if it was a Phil claims. You just had to make sure the | power plug was inserted the right way, or you got no B+ for the tubes.

And these were plugged into Edison's DC system?

Reply to
phil-news-nospam

| The arcing commutator would generate so much hash that all you would | get would be a loud buzz. Any time the brush loses contact with the | armature, it arcs.

And a filter that can remove 60 Hz (or whatever slow rate was in use back in Edisn's day) could not clean up some modulated noise band at higher freqs?

Reply to
phil-news-nospam

| If homes were still fed with DC, the generators would have to be a | couple miles from your home. Also, it doesn't have to pulse to charge a | battery.

If using Edison's 220/110VDC split system, even a couple miles would be way too far. Today would could do transmission, distribution, service, and utilization, and different DC voltages and keep it DC all the way. It would still not be as cheap as AC, but it is possible to do.

Reply to
phil-news-nospam

| Sure, but do you want a 500 KV DC line directly to your home? ;-)

Does anyone have a 500 kV AC line directly to their home? No.

OTOH, 220VDC would bother me more than 480VAC.

Reply to
phil-news-nospam

| Some areas still had DC power well into the '60s and even early | '70s. A friend of mine in the Army told me what his dad had to go | through to get AC for the new elevator in his building near Chicago, | around 1970. The elevator company refused to repair the old DC model, | and only installed new AC powered elevators. People in those areas used | the transformerless radios on the DC power lines, and wouldn't notice | the switch to AC, as long as the usual two electrolytics following the | rectifier were still good.

Some parts of West Virginia had 25 Hz into the late 1950's (my grandfather worked on those). It was there for powering coal mine equipment, but many businesses and homes were connected, as well.

Reply to
phil-news-nospam

That would do it. Did you ever work on one of those radios?

The tube heaters were in series. The filament voltages would add to

117VAC. Sometimes, if those voltages did not add up quite right, the power cord included a resistive conductor to adjust for a lower voltage string. On ac operations, the filter input capacitors would charge up to approximately the ac peak at about 150V from a half-wave rectifier. This meant that 60Hz ripple had to be filtered. To save money, there would be a resistor of about 100 to 200 ohms separating sections of a dual electrolytic capacitor. IIRC, the capacitor sections were about 20µF (microfarads if you cannot read).

I never actually operated one of these sets because I always lived where ac was supplied. I did work in a place where they had dc powered sewing machines. I vaguely remember radios working there. The B+ voltage on dc operation would be lower than for ac operation.

As an aside, IIRC, the dc motors were switched on and of by the operators. Where only ac was available,the motors ran continuously. The operator operated a clutch that connected mechanical power to the sewing machine.

Bill

Reply to
Salmon Egg

Why? Switching could be more of a problem with no zero crossings.

I have a 2400VAC line running along the property boundary line. I suppose it would be feasible to have a dc to dc converter on poles to distribute at the 110VDC level, but I do not expect that in my lifetime. I do not think that I would want it. You might just as well have rectifiers and switching supplies in the individual devices. That is how all of my personal computers do it.

Bill

Reply to
Salmon Egg

Yes, some of them. Edison's system did not vanish overnight, fragments of it lasted well into the era of the transformerless AC/DC radio. As mentioned in a previous post, there were buildings in part of NY that were still supplied with DC until just a few years ago. One of the advertised features of these radios is that they could be run on either AC or DC current which was not the case with the safer and more expensive transformer sets before them.

Useless but related trivia, the band AC/DC got their name from the label on the back of just such a radio.

Reply to
James Sweet

I got my start in electronics/electricity partly by studying/dissecting such radios. They were in fact, AC/DC, they had polarized plugs (at the time they and transformerless TVs were the _only_ thing with polarized plugs, nowadays almost everything has them).

I still remember some of the tube numbers many of those radios used. They had three 12V filament tubes (something like 12AT7 or 12AU7 for at least one of them), a 50C5 audio amp and a 35W4 rectifier. The voltage on this actually adds up to 121V, although the nameplate specified

117V AC/DC.

On ac operations, the filter input capacitors would charge up to

Yup.

These radios were the cheap consumer desktop radios before the transistor radios took over.

Reply to
Michael Moroney

They truly are a masterpiece of minimalist engineering. They cut every corner that could be cut in the name of reducing the cost. Packed components into the chassis however they would fit, wiring is a rat's nest, little in the way of shielding, and yet they do work, pretty well even, and many are still going fine a half century longer than they were intended to last.

Reply to
James Sweet

Yawn. You could post something that makes sense, but you rarely do. Lots of stupid things can be done, but why, other than to prove someone's ignorance?

Reply to
Michael A. Terrell

That has been beaten to death on this, and other newsgroups for years. The mine needs power, and builds the plant. The city grows around the mine, and uses the same system. Old news.

Reply to
Michael A. Terrell

Did you even read what you posted? That is one of your most pathetic attempts at trolling, to date.

Reply to
Michael A. Terrell

A lot of them were sold new for under $10.

Reply to
Michael A. Terrell

No. They were plugged into the cigarette lighter of the flying saucers at Area 51. If you are going to continue to post nonsense, I might as well, too. :(

Reply to
Michael A. Terrell

On Fri, 27 Mar 2009 10:29:42 -0700 Salmon Egg wrote: | In article , snipped-for-privacy@ipal.net | wrote: | |> Does anyone have a 500 kV AC line directly to their home? No. |> |> OTOH, 220VDC would bother me more than 480VAC. | | Why? Switching could be more of a problem with no zero crossings.

That *IS* why 220 VDC would bother more to have it running through my home than having 480 VAC running through my home.

| I have a 2400VAC line running along the property boundary line. I | suppose it would be feasible to have a dc to dc converter on poles to | distribute at the 110VDC level, but I do not expect that in my lifetime. | I do not think that I would want it. You might just as well have | rectifiers and switching supplies in the individual devices. That is how | all of my personal computers do it.

I don't want that much DC coming into my home, especially with utility fault currents.

I would draw the line at 600 volts for AC, and 48 volts for DC.

Reply to
phil-news-nospam

On Fri, 27 Mar 2009 15:34:59 -0400 Michael A. Terrell wrote: | | snipped-for-privacy@ipal.net wrote: |> |> On Wed, 25 Mar 2009 21:44:03 -0400 Michael A. Terrell wrote: |> |> | If homes were still fed with DC, the generators would have to be a |> | couple miles from your home. Also, it doesn't have to pulse to charge a |> | battery. |> |> If using Edison's 220/110VDC split system, even a couple miles would be way |> too far. Today would could do transmission, distribution, service, and |> utilization, and different DC voltages and keep it DC all the way. It would |> still not be as cheap as AC, but it is possible to do. | | | Yawn. You could post something that makes sense, but you rarely do. | Lots of stupid things can be done, but why, other than to prove | someone's ignorance?

So you don't really understand electricity, eh?

Reply to
phil-news-nospam

On Fri, 27 Mar 2009 15:37:54 -0400 Michael A. Terrell wrote: | | snipped-for-privacy@ipal.net wrote: |> |> On Wed, 25 Mar 2009 14:03:30 -0400 Michael A. Terrell wrote: |> |> | The arcing commutator would generate so much hash that all you would |> | get would be a loud buzz. Any time the brush loses contact with the |> | armature, it arcs. |> |> And a filter that can remove 60 Hz (or whatever slow rate was in use back in |> Edisn's day) could not clean up some modulated noise band at higher freqs? | | | Did you even read what you posted? That is one of your most pathetic | attempts at trolling, to date.

Do you even understand filters at all?

Reply to
phil-news-nospam

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