Since a
switched mode PSU needs a load to work properly, what do people use
as a dummy test load for power supplies?
an old automotive headlight.
I was so stingy, that I saved a two filament bulb when one filament burned
out. It no longer had a "low" beam, but the "high" beam provided a
nice
load. It also gave some extra light on the workbench.
Me too.
I have a little board with two SBC lampholders on it, wired to one of
those 4-pin connectors that used to be used for disk drive power. In
one lampholder goes a 12V car side lamp bulb (5W - a bit under 0.5A)
aand in the other a 6V car headlamp bulb (36W - around 6A assuming the
bulb approximates a constant current load. It's not a constant power
load as someone suggested, but I take it constant current was what was
meant.)
Before you ask, my truck (which has 6V electrics) used to take the old
double dippers with two identical filaments one above the other.
Switching filaments switched between a source above the axis of the
reflector and one below, so careful positioning of the bulb and
reflector gave you the dip effect. The bulb had a symmetrical bayonet
because it didn't matter which way round you put it in - reversing it
merely swapped the roles of the filaments.
I can't remember now whether I added a switch to give both filaments in
parallel if a larger load was required.
I wouldn't recommend under-rated resistors. If you're going to have the
load on for long enough to check voltages accurately, measure ripple,
and (could be important) make sure the PSU behaves itself as it warms
up, a resistor could easily catch fire.
Philip.
