Connect light bulbs to power supply

[Sylver]

Hello everyone

I'm really into these electricity topics, and I'm working on a tower mod that we'll see how it turns out... The thing is that I want to light up the subject a bit, and I have some 12V and 50W light bulbs around, which if they could be used for the cause would be great...
My question is how the heck the power supply works exactly, because I don't know if I have to put resistors in like LEDs or if just connecting a bulb to the 12V line already works, considering that they use 12V voltage but consume 50W... or if I can adapt them somehow to be able to connect them to the power supply, the idea is to recycle them in some way.
I've searched for info everywhere but I still don't understand anything, I must be the biggest dunce around... xD

Thanks for reading and for any possible advice <:(
Best regards!

[cobito]

Incandescent bulbs are not put resistors. In fact, if you put the typical resistor that is put on the leds, it will come out burning. A 12V and 50W bulb needs a current (P=V I) of 50/12= 4.2 A, so connected directly to any 12V output that provides that intensity, it will work without problems. Keep in mind that 50W is a lot of power to dissipate for such a small bulb which means it gets very hot. So be careful if you put it near plastic elements and ventilate it well because if not all that heat stays inside the box and decreases the efficiency of dissipation of all the elements of the PC. If you want it to light less (and dissipate less heat) you can connect it to the 5 V. Taking into account Ohm's law (V=IR), that bulb has a resistance of 2.867 Ω, which means that at 5V you will need a current of 1.75 A and the dissipated power will be only 8.72 W (almost 6 times less). If you want intermediate power you had to combine lines of the source (for example 12-5 =7V) with what you would get about 17W although I am not sure to what extent the lines of a PC source can be combined and what is the maximum power that these combinations can supply. Another option for regulation would be to use the 12 V line along with PWM modulation and darlington transistors (or any NPN of power), but that is already another story.

[Franziskaner]

let Cobito put in 100W bulbs and make them into heat sinks :troll::troll:
regards

[Sylver]

Buah, just all the information I needed Thank you so much cobito, it has become absolutely clear to me, and I have searched…

Now I have to worry about the cooling of the bulbs, but it will be in the outer area, there is no problem that the heat stays inside, I will make an external cooling circuit.
I reiterate, thank you very much, I did not remember that in matters of science and mathematics you are at the forefront of the forum

¡Saludos!

[Franziskaner]

that will be something like this

!
:troll::troll::troll::troll:
greetings and sorry for the SPAM

[ferelxyx]

you have it easy in the power supply the yellow cable and one black one gives you 12Volts
the red and one black one gives you 5Voltios
and the yellow one positive and the red one negative gives you 7 Voltios approx

but put low consumption bulbs or Leds, to put 50W bulbs you have to be well above the power supply
and if they are halogen forget it or you will burn the casing and or the cables, you would have to put a relay
or put silicone casings or something similar for the heat

PD: I explain it to you in simple words so that you understand

regards

[Sylver]

Yes, you are absolutely right ferelxyx, I certainly should have more than enough source... although to be honest, I have only found two 12V bulbs, at most they will consume 100W, equivalent more or less to a mid-range graphics card, and I don't think I will assemble an ultra-powerful system in the tower I am modifying, at most an HTPC for cinema or little more, it is more for the aesthetic luxury than for everyday use.
I will put the bulbs in the front with an external cooling system based on a strange design that I have come up with, and if everything goes well and I don't end up with a disaster of a mod, I will post it in the Modding subforum, which has been pretty dead lately

Best regards and thanks!

[ferelxyx]

it is better to buy high brightness LEDs so you have a lot of light and low consumption and minimal temperature

you have LEDs from 2.6v to 3.2V - in all colors except amber and red which are 2.6v maximum
in LEDs, the short leg is the negative, and the long leg is the positive
3mm - 1000 mcd's there are 7 colors
5mm between 10,000 and 40,000 mcd's there are 7 colors
10mm generates 135,000 mcd's. (WHITE COLOR)

you put a 470/510 Ohm resistor and you can connect them to 12V DC from the source or for the car
the resistance does not matter in which position it is and you put it on the red wire on the positive leg

it is also possible to place some LEDs without resistors in a 12V-14V source
you place the LEDs in series, joining the negative leg of one with the positive of another, we can put
like this about 4 LEDs and 5/6 if they are amber or red

regards

[Sylver]

Thank you very much, I have already researched about LEDs and understood the theory, they were my first option, but the problem is that they do not sell them individually in my area, specialized stores are scarce... One option was to order the material online, but the shipping costs complicate things...
The truth is that the best plan is to assemble LEDs in series, but right now I am short of material. I thought about getting some LED strips from China and stuff, but all the gadgets I find have some drawback, whether it's connections, power supply, soldered on boards, in car bulbs... Although LED boards for car interior lighting could work, right? considering that they are for 12V power supply... what do you think about this? Should I buy a couple of bulbs of that type from China?

Best regards!

[ferelxyx]

if they serve you but you would have to solder some cables to be able to connect it
with an electronic tin soldering iron if you have one or a friend or acquaintance who can do it for you

if you don't have that option you can connect the cables with clamps or something similar
or you put some cable ties or something like that and put insulating tape and that's it

regards

[cobito]

Well, the voltage of the led depends on the color it emits. Each color involves a different composition of the semiconductor and this varies the forward voltage. For example, 5mm red ledes that are made from gallium arsenide have a forward voltage of 2.2-2.4 V and blue, green or white ones of 3.3-3.5 V. On the other hand, the resistance also depends on the type of led. 5mm blue, green or high brightness white ledes use resistors of 470 Ω for 5 V supplies or, they can be placed in series to save the resistor, which in the case of green, blue or white ledes would be 4 for 12 V voltages and in the case of red ledes would be 6.

Resistors are used exclusively to create a voltage divider and be able to power the ledes at their nominal voltages using generic sources, but not all ledes use the same resistors at the same voltages since each one presents a different resistance that varies the supply voltage (Vo=Vi R1/(R1+R2) where R1 is the resistance of the led and R2 the chosen resistance).

This is talking about 5mm ledes. For power ledes (10-100W), the voltages are completely different that no longer only depend on the color but also on the power and, of course, the typical 0.5 W resistors cannot be used for obvious reasons. Due to the non-standardized voltages of this type of ledes, the regulation is carried out by electronic means.

EDIT: I see that ferelxyx has made a good explanation.

[Sylver]

Excellent contributions, friends, you are masterfully enlightening me on the subject. Soon I will put together a small guide for connections and lighting mods in the field of computing :sisi:
I think I will go on the 1st to buy some LED panels for cars like the one I put above, since using 12V it will be very easy to solder a couple of wires on each side and get going. As for the bulbs, I will probably leave them as a spare for some study lamp, it will be more cost-effective and safer… :chuckles:

Many thanks again for the great contributions and for the trouble taken, I wouldn't have gotten so much information or understood it better even if I had asked an electronics professor

Best regards!

[Franziskaner]

@Sylver:

Great contributions, friends, you are masterfully enlightening me on the subject, and soon I will come up with a small guide for connections and lighting mods in the field of computer science :sisi:
I think I will go on the 1st to buy some LED panels for cars like the one I put above, since with 12V it will be very easy to solder a couple of wires on each side and get going. As for the bulbs, I will probably leave them as a spare for some study lamp, it will be more profitable and safer… :chuckles:

Thank you very much again for the great contributions and for the trouble taken, I wouldn't have gotten so much information or understood it better even if I had asked an electronics professor

Best regards!

as it seems like you don't stop :troll: if you want leds send me a PM and I'll tell you.
P.D about the leds in series …. it's true that they usually don't break but if for the sake of life one breaks all the ones in series stop working

[cobito]

@Franziskaner:

P.D about the leds in series …. it is true that they usually do not break but if for the things of life one breaks, all the ones in series stop working

The thing can get much worse. Sometimes, when an led breaks, its terminals short-circuit and this causes the remaining leds to receive more voltage than they should, causing them all to burn out or be in pretty bad condition.

[Franziskaner]

just to clarify that I don't work at that store, nor do I have any benefit, but since Sylver says they don't have any store near me, it doesn't cost me anything to go to that store or another one in Barcelona and send the leds by mail (I don't think that's a buy and sell, more like a courier service :troll:)
sorry for the long explanation
regards

[Sylver]

Hey, that's a good initiative, if I don't get the LED panel idea to work tomorrow, I'll let you know and we'll see how the market is :sisi:

Regards