12-volt halogen-bulbs on Dell power supplies

I'm trying to use three 12-volt 20-watt rail halogen bulbs.
These bulbs will shine on paintings, kitchen cabinets and an
armoire. Is it safe and efficient to use halogen bulbs with a 60-
watt constant current computer power supply compare to a
halogen transformer? Also, will the computer power supply
work with a standard household 600-watt dimmer?

TIA, Tibur

 

First, a computer power supply is constant voltage; not
constant current. Second, computer power supply typically is
rated at 60 watts distributed among the many voltages. 60
watts not output by every voltage. Third, dimmer on power
supply input will do nothing useful. It will only make a
power supply test circuit. Either that power supply will
output constant voltage, or it will shutdown. Dimmer on power
supply input will not reduce voltage output. Forth, a 20 watt
halogen may demand up to 100 some watts for a very short time
when starting. How the power supplies foldback current
limiting responds to this is a response unique to that power
supply.

Question - does power supply output voltage even match
voltage of halogens? Better, safer, and cheaper to power
halogens from a transformer designed just for that purpose.

 

Probably. The 12VDC bulbs will use 5A total. Computer power supplies will
produce lots of amps at 12V. This one

http://www.antec-inc.com/specs/true330_spe.html

can produce 17A at 12V. You need to ensure that your computer power supply
will supply more than the required 5A at 12V.

Also, will the computer power supply

Sadly, no. Dimmers work with things like lightbulbs by changing the AC
waveform. Unfortunately, you computer power supply is undoubtedly a
switchmode power supply, which will just freak out and misbehave if given
this odd waveform. You can dim the lights at the bulb side by varying the
voltage or 'duty cycle' into the DC bulbs (using a circuit between the power
supply and the bulbs). Its not just a matter of buying something from your
hardware store, however.

Regards.

Bob Monsen