Hi Riley & Folks,
I've snipped a lot of this - not that I find it to be uninteresting, but
others might :-)
On Tue, 6 Apr 1999, Riley Williams wrote:
> To my way of thinking, any mains-powered ham radio gear needs to be
> designed to work with the mains supply of the countries it will be
> used in, so this is at worst only slightly off topic...
Well, *most* ham gear I see works (to spec) over quite a narrow range of
input voltage - 11.5V to 14.6Vdc, and fails (into a permanent fault
mode) at an input voltage of 16-18Vdc or so.
The DC power supplies normally sold/used for powering the 12V kit have an
output of 13.8Vdc and in failure mode (regulator E-C short) this frequently
rised to >20Vdc - hence expensive RF power transistor/module failure. The
designers have never heard of crowbars or indeed fault-tolerant design.
(There was a long discussion about the design of a certain G4's 12V dc
PSU for his new HF tranceiver - it occupied GB3DA (a 2 metre repeater
near Chelmsford and frequented by a number of Marconi employees) for
several weeks and made the journey home considerably less tedious.)
[Electricity regulations]
> Very true, but they are still important despite that.
Important - but not definitive..
> Also from OFFER is the following quote: "Whilst we regulate the
> Electricity Supply Industry, manufacturers of electrically powered
> equipment should refer to the current Electricity Regulations for the
> specifications that their equipment must comply with." From a design
> perspective, THAT is the important point.
Of course - then they don't have any responsibility.
However - the requirement must be for equipment to work with the (range
of) power supplied, and not to suffer damage under allowable fault
conditions. In other words, equipment should work with the range of *supply*
voltages offered (230V -6 +10%) plus allowable fault voltages. If the
supplied voltage exceeds these (allowable) limits, then the supply company
will compensate for any damage done (and they do!).
> Curiously enough, the PSU on the computer I'm using at this moment has
> a voltage selector switch with the following options on it:
>
> 110V
> 115V
> 120V
> 130V
> 220V
> 230V
> 240V
> 250V
>
> Does that count?
Erm - the computer that I am typing this on has a power supply that
specifies:
INPUT:100V-240V ~ 0.95A-0.55A 50-60Hz
It is the PSU for a Toshiba 460CDT (running Linux of course).
Most desktop PC's have at most 220/110V (or 230/115V) input switching.
These power supplies invariably have a bridge input circuit feeding two
series connected reservoir capacitors. One side of the mains input is
connected to the junction of the two capacitors - thus creating a
half-wave voltage doubler - on 110V.
> > Increasingly, equipment has an allowable input voltage of
> > nominally 100V-240V without adjustment.
>
> If I knew of a design for a power supply that would do that, believe
> me, I'd use it...
Er, a switch mode PSU, with a first stage switcher that provides about
100Vdc which powers the "normal style" of SMPSU that gives the required
output voltage(s).
The first time I met one of these was in a HP 1610A logic analyzer in
about 1978. It used a mains frequency SCR switcher to produce the 100Vdc
which then powered a SMPSU.
Many single stage SMPSU will accept a 2.5:1 range of input voltage.
> > The "Red Flag" was required to be carried by a man walking in
> > front of a motor car to warn the public of its approach!
>
> Thankfully, that's long since been scrapped...
>
> > I can think of no parallel to the red Flag in Linux...
>
> The 20 Meg hard drive springs to mind...
I was thinking more of a certain EULA...
>
> > ...but I can in ham radio - it is call Morse Code!)
>
> I disagree with you re that being one in Ham Radio on two counts:
>
> 1. The "Red Flag" has been scrapped, Morse Code hasn't.
But it is no longer used (except by traditionalists).
> 2. I may only be a class B but I'm AGAINST the scrapping of the
> Morse test for advancing to class A. By all means provide one
> or more ALTERNATIVE methods, but the Morse test should remain
> as an alternative for those who prefer it.
Yes, exactly my view.
> However, as a genuine parallel in the Ham Radio world, I would offer
> the use of AM modulation for voice contacts, which has long since
> vanished from the scene...
Has it?
> > Sorry again folks to be so widely off topic, I did manage to get
> > a mention of both Linux and ham radio in the last
> > paragraph......:-)
>
> 8-)
I got both in again :-)
> Best wishes from Riley GM7GOD.
Fraternal greeting too - Geoff g8gnz
--
Geoff Blake [EMAIL PROTECTED] linux 2.0.36
Chelmsford [EMAIL PROTECTED] sparc - i586
Intel create faster processors - Microsoft create slower processes
