27 Apr
2011
27 Apr
'11
12:38 p.m.
On 26 Apr 2011 at 20:17, Tony Duell wrote:
The output cirucit of most PSUs has a sizeable capacitro across the
output terminals. That will take a high current at switch-on too.
I've never had a PSU that has a problem powering a suitably-rated
filament lamp. Such PSUs probably exist, but it's not somethign to worry
about. Of course if the PSU won't start up, then you have to investigate
why, and it might be the inrush current of the load (but if it is, I
would suspect there are other problems with the PSU)
A 6V 6W bulb (which is easy to get) would draw 1A
and be most
suitable.
Unless inrush current matters (as it can on many PSUs with
overcurrent protection). At the moment you switch the PSU on, that lamp will draw considerably more current until it
reaches operating
temperature. My point was that by using a higher-voltage lamp, the
difference between "cold" and "operating" resistances is much less.
Ture, but given that a 110V 110W bulb is essntially an 8 ohm resistor
when cold, you might as well use a, 8.2 Ohm wire-wound resistor across
the 5V terminals. It will dissipate a little over 3W (and for testing, I
would be suprised if a 3W 8.2 Ohm resistor wasn't adequate).
-tony