30 Jun
2008
30 Jun
'08
5:59 p.m.
On Monday 30 June 2008 20:39, Eric J Korpela wrote:
How much effort you want to go through depends upon
how much you value
what you are powering. The cheapest solution is to go to a flea
market a find a power supply.
Dual secondary windings is a good idea, but it's not that much savings
over two transformers.
It'll likely be a savings in space, but also may end uip costing more.
I wouldn't use a non-switching regulator for the
5VDC, unless you need to
warm your house. I'd get a switching 28V->5V 10 to 20W isolated DC/DC
converter for the DC portion. But in any case, this supply is going to cost
more that two wall warts would and, depending upon how skillful you are at
building it, it may not be any safer or more reliable.
I guess a question is, what fraction of a typical machine's value
should you spend on protecting it from its power supply? For rare and
valuable machines, should we be building supplies with dual switching
converters with 6kV isolation, diode mixed with over-voltage and
over-current protection and a soft start circuit? Or is a $50-$100
regulated bench supply for each voltage good enough? I worry about
this every time I turn some machines on....
A switcher isn't necessarily going to provide more in the way of protection.
If one is worried about what the supply might do to equipment in terms of
overvoltage the simplest solution is to put a crowbar at the output of it,
along with an appropriate fuse. If anyone doesn't know how to make one of
these I can describe it pretty simply, just let me know...
--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, ?a critter that can
be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters"
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Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin