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Yes Sven,
You're dead right!.
The Negative pole of the socket is the larger of the two, to prevent reverse polarity.
The socket actually has 2 positions, one for 45VDC and the other for 22.5VDC.
Not sure why you would need that voltage, unless of course you were going to use two batteries in Series.

Some radios used a lower voltage for the detector and a higher voltage for the audio amp plate.

Dual-output batteries with a tap part way were pretty common at one time. Although it's easy to think of tube/valve sets as needing relatively high HT/B+ voltages, many of the low-signal tubes for battery receivers were designed to run on quite low voltages.

Some of the older sets used a separate grid bias, or "C-" supply, negative with respect to chassis. This could be either a separate battery, or incorporated as part of the main HT/B battery (although the grid bias section had negligible load on it).


I have one of those old, huge "Everything Within" household books from the 1930s which has a whole chapter on "wireless."

Those fortunate enough to have D.C. mains, it explains, can charge their accumulators by unscrewing the cap from a light switch and connecting the accumulator across the terminals so that the light acts to limit the charging current.

And how do you determine the polarity of the switch terminals? Why, you take two pieces of wire, drop them into a beaker filled with a vinegar solution, and observe from which conductor the bubbles rise.

Can you imagine the legal types at the publisher allowing them give advice like that these days?




[This message has been edited by pauluk (edited 11-01-2005).]

Ouch! I've had my fair share of scary DIY advice from old books, but that one easily tops it all!

I have an old electrical book where the writer frowns on the use of lamps in series to obtain a charging voltage off dc mains- but his concern was only the damage done to cells by poor voltage control, not the safety angle! He also castigated the use by some ingenious tightwads who had discovered that there was a small voltage differential between neutral and earth and had used this free current to charge batteries or even operate the servants' bells to summon the serfs! He recommended taking accumulators to an 'expert' at a Wireless Shop, where proper facilities existed and the life of the units was thus assured. Our pub-landlord used the bulb method, ( by then ac- how it was rectified I have no idea.
In the days when children had to be parked, by law, outside of drinking dens, (while ma and pa had a small beer), fobbed off with a bag of broken-crisps and a bottle of pop, I remember we kids used to occasionally sneak round to the charging shed at the back. A faint dull red glow of several small lamps could be seen on the bench, the rest of the shed was in velvet darkness. "Child-rumour" was that 'they' kept a mad-grandmother/rabid cats/a monster chained to the wall in there, so we used to have a quick peep and run off terrified back to the well-lit frontage.

I saw similar advice in a book of similar vintage, but this one involved a 5 amp plug and socket in series with the 5 amp lighting circuit main, and a car battery. Apparently 'the reduction in voltage to your lamps will be insignificant and will actually reduce your lighting bill'.

Mention was also made of the vinegar water polarity test, with salt water not recommended as a test as both electrodes will bubble.

A stern warning was made not to attempt this if you had AC mains.

A 'shorting plug' should be provided to allow normal usage of the lighting with no battery connected, and connections to the battery should be made before connecting the plug.

No mention was made of the effects of interupting ~5amps DC around the hydrogen/oxygen buildup that would have been present in the 'cupboard under the stairs' at the time. It was probably assumed that anyone attempting this would have knowledge of this danger.

A more innocent time, for sure. (No mention of part P was made either Paul )

I think the key point is that in those earlier times people did and were expected to take more responsibility for their own actions, a sentiment with which I agree fully.

These days, somebody cuts toward himself with a Stanley knife, nearly removes half his insides when he slips, spends a week in hospital, and then tries to sue the tool manufacturer for not warning him that a sharp blade could cause injury.

By the way, you should see some of the advice in the medical section of that book.

There's an interesting little section about a substance which is apparently full of medicinal qualities and can be cultivated easily in any warm spot, such as the corner of a greenhouse, so that a ready supply will be available should it be needed.

The name of this wonder medicine? Cannibis!

Back in the 1970ies Vienna tramways didn't have automatic doors, the doors were just left open. During the last few years of these cars (the last one pulled in in 1978) they wrapped some trees next to the tracks in red and white plastic because people had been sept off the cars because they didn't notice the trees... nowadays not even that would be enough... but these cars are still legal for special services.

In 1978 I was visiting France with my Mom and Dad, we stayed with their friends in Esply (sp?)

Anyway we would take a high speed train to Paris and we could open the doors anytime we wanted. No one seemed surprised that 14 year olds where playing at an open door.

Vous voudrez mourir? J'm'en fous! Vive le sport!

Alan


* You wish to die? I don't give a ****! etc....


[This message has been edited by Alan Belson (edited 11-06-2005).]
I'll get it right in a minute!

[This message has been edited by Alan Belson (edited 11-06-2005).]