Kitchen Undercounter and Cupboard LEDs Project With a Computer PSU


Postby Benbb » Fri Mar 04, 2016 1:55 pm

Hi all my first post so take it easy,
I have utilised a car headunit and a psu I had lying around in the garage to make a stereo for my kitchen + conservatory, and I'm now looking at hooking up some strip leds to the psu for some undercounter and in cupboard lighting in the kitchen. For the cupboard lighting I was looking some push to break switches, but can only seem to find them rated at 2amps, I tested the 12v rails on the psu they are just over 16amps, I don't think the leds will need more than 2amps so my question is it safe to run 16amps into the 2amp switches? Will it just step it down to 2amps or will it get hot risk a fire?
Cheers for any replies
Ben
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Postby ericmark » Fri Mar 04, 2016 10:44 pm

LED lamps are current devices and some where you need some electronics to change constant voltage to constant current this is normally inside the bulb but with strips it may need a constant current driver.

The problem with a car replacement power supply is a car battery is charged and float charged at between 13.4 and 14.8 volts according to the system used. So in a caravan for example I can't use typical house bulbs as the house bulb is rated 12 volt where I need a car bulb rated 10 ~ 36 volt.

Assuming you have the correct driver for the strip then it will only take what current it needs so a 24W strip will only take 2A. However if something goes wrong then it could draw the full 16A before the power supply closes down. So normal method would be to include a fuse. Likely a 3A blade fuse in a in line fuse holder.

Some times strips of LED lamps have simple resistors to limit current and some times they use a PWM power supply chip, and some times they expect you to use an external LED driver.

Driver should mean current regulated but some manufacturers call anything used to supply a LED a driver. It needs some careful reading of the specs.
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