30 Sep 2003, 20:05, Roy J. Tellason (1:270/615), wrote to JIM HOLSONBACK:

Hi Roy.

 JH>> So which particular automotive light bulbs would you recommend 
 JH>> for testing each of these? (Remembering that the pins of the ATX 
 JH>> standard power connector are rated for 6A Max for each pin).
........................

 RJT> How much current does a typical headlight draw,  anyway?  I'm 
 RJT> thinking that a sealed beam with one of two filaments burned out 
 RJT> might be handy.  Tail lights aren't that heavy a draw,  and I 
 RJT> think a stop light is only going to something like 4A or so,  
 RJT> but it's been a while since I measured any of that stuff.

I just checked an H-6054 (12V Halogen Sealed beam) and got 2.5A, 5A and
7.5A connecting to low, high, and both beams respectively.  The start surge
is pretty good, cold filament to High contact gives 10A, and tapers off to
that 5A above as it lights.

Same bulb can also be used with the +5V, with a proportionately lower
amperage drain, but good enough for initial testing.  I usually use _both_
filaments on the +5 and another bulb on the High Beam filament for the
+12V.  

Since the ATX PS's put out such heavy amps on the 3.3V line, and that line
powers the CPU _and_ the RAM, I'd suspect the 3.3V is now the most
regulated voltage.  I haven't done much yet in that area, but when I do,
I'll probably use three headlight bulbs in parallel, with _both_ filaments
connected just to get a minimal load.

The remaining voltages are just derived voltages, and probably aren't too
important to load.  The (-12V) is always reverse-connected to the PS fan,
so that covers that one.  I don't believe anything has used the (-5V) line
since the days of the 16K RAM chips!   :-)

I'm also finding a lot of handy uses for those 'Garden Light' bulbs as they
are also 12V, same physical size as automotive side marker and trunk
lights, and the packages are available marked in 4W, 7W and 12W sizes which
takes out a lot of the guesswork and lookup tables (which I've no longer
been able to find).


     Good luck...  M.

--- Msged/386 TE 06 (pre)