From: Patent Tactics, George Brock-Nannestad
just a few comments on power supply and mains. In Denmark, the foremost
source for amplifiers were batteries for High Tension and accumulators for
the cathodes. So-called "battery eliminators", i.e. mains supply converted to
suitable z.f. voltages, were an important item, and actually the major
selling product of Bang & Olufsen when they were founded. Note my use of z.f.
(zero frequency) for DC; it was to honour M.G. Scroggie of wireless fame who
used this term because he thought that DC voltage was an abomination.
Danish mains was DC (back to normal, again) for many years in many parts of
the country, and the last place to give in to AC was Copenhagen; it only
happened in the early 1960s. Gramophones had universal motors (some neat
little things, but very good).
Fuses and switches for DC have to have a much sturdier construction than for
AC, because you really have to break an arc, whereas in AC there are two zero
crossings of the current per cycle. This means that you do not need nearly as
much cooling of the ionized gases to prevent re-ignition when the voltage
goes up again. In the US, using 110 V for housing, the fuses and switches
again have to be sturdier because the amperage rating is higher.
In the UK, things are very interesting indeed. They do not have main circuit
breaker fuses but fused outlets, or rather fuses in the plugs. And very many
use ring mains, i.e. the circuit through the house has two parallel circuits
going round and back to the main switch. This very much reduces the voltage
drop on the in-house distribution. This is in sharp contrast to the star
system used in Denmark, but I suppose you need it because the "normal" plug
for kettles and the like has a built-in 13 A fuse, and you can have both your
kettle and a toaster on at the same time. Not so in Denmark, you are limited
to 10 A. A normal fuse has a time function that makes it blow instantly at
1.5 times the rating, and I suppose in one hour at 1.1 times the rating - I
haven't checked since 1970.
All the things you did not want to know about mains! And we have not even
started on 3-phase.
But Tom's photographs are beautiful!
> Hi, Tom,
> Wow, what memories this brings back. The only equipment that I have ever
> owned that included these was a 1981 Canadian-market electric range. The
> last house I had that used these was the old house I had in Canada from
> 1981-1983, and a new service entrance and breaker panel were some of the
> first things I did to the house. My old house in NY City lost these
> about 1965--it was originally built in 1921 and had a single phase,
> three wire service entrance with two of the 30 Amp fuses as mains. The
> replacement had a two-pole 70 amp breaker. I upgraded the 100 amp to 200
> amp in my 1984-2004 house in California and the house here came with a
> 200 A breaker panel.
> These are not the best devices, but they certainly were pervasive. The
> Fusetron fuses had diameters that were keyed to their ratings, so you
> could not put in a different size once you screwed the adapter into the
> "edison base" socket (same as a lamp). The adapters had anti-removal
> pawls/springs so once the mod was done, it could not be easily undone.
> My 1921-built house had fuses in the neutrals as well as the hots!
> I'm mentioning this on-list because there are many non-North-American
> list members who might have a bit of curiosity about how domestic sound
> reproducing equipment received its power--these were the prevalent
> protection devices from before the 1920s into the 1950s.
> On 2012-01-16 6:23 AM, Tom Fine wrote:
> > All that you see here:
> > http://beverage-digest.com/images/fuses/
> > yours for the price of shipping.
> > Not sure if anyone uses these things anymore or if there are old
> > equipment installs that use them??
> > Ping off-list if interested.
> > - -- Tom Fine
> Richard L. Hess email: [log in to unmask]
> Aurora, Ontario, Canada (905) 713 6733 1-877-TAPE-FIX
> Quality tape transfers -- even from hard-to-play tapes.