Re: New BBC soap: Bert Coules?

One street in Chesterfield was on 130Vdc until the early 70's!!

It must have been very difficult finding appliances that worked on DC, and on a lower voltage.

Light bulbs would be fine - use US-standard 110 V instead of 240 V. Likewise for cookers and electric fires. Power may be limited because you'd need twice the current to produce the same heat/light on half the voltage, and the feeder cables and rectifiers may not be able to supply that.

Some motors (universal motors) would have been OK - in vacuum cleaners etc - as long as you designed them for the lower voltage.

Electronic appliances such as TVs and mains-powered radios would need to be designed specially, because you can't transform DC up or down, so you need another means of converting 130 V DC to the low voltage for the electronics and the EHT for the TV tube. One way would be to use a rotary converter (DC motor driving AC generator) to produce AC of normal 240 V.

I wonder where the power was generated. By a local DC generator, or from the National Grid but transformed down and rectified?

at the same time as Cambdge, generally, had 200v, one college had 50v ac.

The connections are designed to match the standards for charging at the maximum available speed. The tree types are AC, as used by a few makers, with all the really smart bits in the car, DC, which controls the DC fed to the car according to what the smart bits in the car say, and the last, motr recent one which is also DC, with smartness in the charger and the car.

The only cars not compatible with the three way chargers are Teslas, and small stuff like the G-Wiz and Renault Twizy, which can only charge using a 13 Amp or type 2 connection.

For the two slower rates nd the very fast AC chargers, that is true,though the AC ones can select single or 3 phase according to what is requested.

The ones I remember had a valve rectifier for the HT, direct off the mains, and a dropper resistor with taps on to feed the heaters, which were all chained in series.

These sets were so old that they had been designed to work off AC or DC mains supplies.

(Wow!)

Don't have to go US - I think 110 was (is?) common in various parts of UK. A lot of industrial sites use 110V (often centre-tapped to earth, as well, I think), and I _think_ BR used it in train carriages (possibly to reduce pilfering?).

Interesting point there: was it "raw" DC, i. e. rectified AC (or generated, which would produce similar), or somewhat smooth? (If the latter, how?)

Yes. Most electronic devices by the '70s would have had a PSU based around a 50 Hz transformer, so not only would they not work, they'd go bang if connected to DC.

The EHT in all but very early TVs is generated by the electronics anyway, not (except in a fundamental sense, of course) from the incoming supply.

Woody, it'd be very interesting to hear how the people of that street _did_ manage (with things like electronics). Also, did they have some very unusual mains sockets (to prevent - well, reduce - the chance of someone plugging in an AC-only appliance?)

In message snipped-for-privacy@mid.individual.net>, John Williamson snipped-for-privacy@btinternet.com writes: []

Is that for use in rural areas, where there aren't many lampposts? (Sorry - IGMC)

Surely not - the 230V 'unufied' voltage is intended to encompass both 220V and 240V ranges and theie tolerances.

So 240 ± 6% = 225.6 - 254.4 and 220 ± 6% = 206.8 - 233.2

but 230 ± 10% encompasses both ranges, being from 207 - 253 so no change needed either side of the channel.

As Ian said earlier, the tolerance is asymmetrical: +10%, -6^.

I was brought up to understand that our mains voltage was 230V and it somehow morphed itsef to 240V without anybody noticing!

When I went to school in West Ham, the voltage was 215V and all of the cabling in the streets was replaced before the upgrade to 240V

Not far away, Ilford had generated 600V DC for their tram network in 1901 and found it convenient to use the same plant to provide 200V DC to residents.

I don't know how the changeover was managed because it was

In message snipped-for-privacy@255soft.uk, "J. P. Gilliver (John)" snipped-for-privacy@255soft.uk writes: []

That "^" should have been "%" of course.

I think you may have exagerated a bit there!

All the TVs I encountered in the black mand white and early colour eras were AC/DC with, usually, three taps: 190-210V;

The 1938 radio I grew up with was AC only but had the same three voltage settings.

More a case of mains transformers being expensive and dropper resistors cheap!

They also had the chassis connected to one side of the mains and most had reversible 2-pin connectors so it was a 50/50 chance if the chassis was live or not!

Shortly after I started work the building was extended and the new shop was complete ecept for a hole in the concrete floor where the supply cable ran though from next door en route to the shop on the other side.

When the man from the electricity board turned up with his litle rubber mat and sat on the edge of the hole patching our new feed onto the live feeder we all said "Sod that for a game of soldiers" or words to that effect and trooped back upstairs to our workshop and carried on working on all these lethal sets without a care in the world!

Doesn't sound that much different to the change over from coal gas to natural gas.

I'm pretty sure that the pegboard had a lot more than just three voltage ranges, though I could be wrong since it was about 50 years ago.

How did DC-fed TVs generate the EHT, given that you can't transform DC by a step-up transformer and a ladder of capacitors and diodes, as you can with AC.

In the days of mains voltages which varied from one place to another, was each town's electricity generated locally to a different spec, or were all towns connected to the national grid but with different transformer ratios in different towns? Did the change of a town from a non-standard voltage to

In message snipped-for-privacy@news.eternal-september.org>, Terry Casey snipped-for-privacy@example.invalid writes

In 1948, the Northumberland village where I was born 'got the electric'

- and I believe it was supposed to be 235V. We had the type of 3-pin plug where the live pin was a screw-in 13A (or whatever) fuse.

They did it the same way as AC sets. The EHT was normally generated by a winding on the line output transformer, then fed into a diode tripler circuit. The fact that it happened at line frequency made all the capacitors and inductors much smaller and cheaper, more than offsetting the cost of the extra winding.

The different voltages were generally a result of each town or city having their own power station and distribution system, and as they were connected to the grid, voltages were standardised across the country.

Don't know about ancient sets but a winding on the line output transformer was the normal way to do it. Or are you thinking of the anode voltages for normal valves? Same way as battery sets I should imagine, oscilator at a few kHZ and transformer, the highish frequency means your don't need a particularly large transformer.

The former, the first parts of the grid weren't built until the late '20's early 30's. In response to fragmented an ineffcient mish mash of private localised power companies.

Kind of like the modern boost converters that are used in cheap car laptop chargers and the like.