resistor needed for stepping down from 50 to 25watts on lighting

[topjimmy]

Hello,

I have a 150watt power supply with the following specifications below, that powers 50watt 24VDC light fixtures. Currently, you can only connect 3 light fixtures to this power supply and I'd like to connect 6 fixtures at 25watts by limiting the power draw on the 50watt fixtures down to 25watts. What kinda of resistor would need to ensure each fixture is maxed and restricted to 25watts?

Power supply Specification Details :

Electrical

Input Voltage 100 – 240 VAC, auto-switching, 50 / 60 Hz

Maximum Input Current 2.8 A at 115 VAC, 1.4 A at 230 VAC

Power Output 24 VDC, 150 W maximum
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please email at: jsg@zoomtown.com (for faster response)
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Thanks

Jim

 

[Nigel Goodwin]

Buy 25W bulbs and fit those - reducing the power to existing bulbs will drastically decrease their light output, alter their colour massively, and shorten the bulbs life if they are halogen.

It would also be VERY inefficient - bulb output would be only 12.5W, with 12.5W wasted as heat in the resistor.

 

[4pyros]

You can not use resistors because thay will be using up power to. Put two of your lights in series three times and you will have all six lights powered at half power.

 

[Grossel]

You can not use resistors because thay will be using up power to. Put two of your lights in series three times and you will have all six lights powered at half power.

Each PAIR of bulbs will theoretically output half the power of one lamp. But since a light bulb's current isn't linear to the current the serie bulbs will output more then half power. Mostly as heat, and little light.

 

[MikeMl]

You can not use resistors because thay will be using up power to. Put two of your lights in series three times and you will have all six lights powered at half power.

But each lamp will be operating at 1/4 of its rated power, which will make it not useful as a source of illumination. It will will be glowing red, and not putting out hardly any useful light.

 

[ADWSystems]

Option 1) get a lower wattage light bulb.

Option 2) use a capacitor instead of a resistor...no heat generated. Xc = 1/w*C

 

[Diver300]

Option 2) use a capacitor instead of a resistor...no heat generated. Xc = 1/w*C

You would need a huge capacitor for that if the transformer gave out AC.

It's a DC output transformer so a capacitor won't work anyhow.

 

[ADWSystems]

You would need a huge capacitor for that if the transformer gave out AC.

It's a DC output transformer so a capacitor won't work anyhow.

Missed that DC thing. Sorry. But you have to admit that most people don't reach for a capacitor to use as a resistor in an AC circuit though.