How to Choose a Computer Power Supply [aboutcomputer99.blogspot.com]

How to Choose a Computer Power Supply [aboutcomputer99.blogspot.com]

Question by ronald c: How can I modify a computer power supply to use for powering a solderless breadboard for projects? I'm trying to use a surplus computer power supply to use on my breadboard for projects but I can't figure out how to get it to sense an action to power up. I'm trying to not go out and buy a regulated power supply from Fry's for @ $ 30-50. I probably have like 4 power supplies laying around, so I'm just trying to put them to use instead of throwing them out. Or, Where do I go on-line to talk to someone find that kind of information? Best answer for How can I modify a computer power supply to use for powering a solderless breadboard for projects?:

Answer by Joe M
You will be much better off with the regulated power supply. Get one - you won't regret it. Maybe see if you can throw the old computer power supplies up on e-bay and get a few dollars towards one.

Answer by Colinc
There are live 12v and 5v supplies to the motherboard constantly, this is used for sensing activity as in operating the switch. For the average electronics project these may suffice.

Answer by Bjorn
You would have to set up some kind of switch for the power supply to get it to turn on when you wanted it to. Generally, it is the 3rd pin on one row of pins and the 4th pin on the other row. This would be a green colored wire and a black colored wire. Just do a google search for what you are looking to do, there are plenty of people who use computer power supplies for just such a thing. Try http://www.hackaday.com

Answer by formersalt
Most power supply's (especially older ones) need some load to start functioning. Anything like an old drive, hard or floppy, will get the job done.

Answer by David M
The power connector on smps has 2 voltages +5v and +12v the red wire is +5v the yellow wire is +12v the black is gnd. the voltage between the red wire and black wire is +5v the voltage between the yellow and black wire is +12v their is no common ground its a floating ground watch your current draw.

[computer power supply]

Choosing a computer power supply is easy, provided that you are not making the mistakes that other people are making. One of the most common mistakes people made when building their own computer is to neglect the importance of computer power supply. They tend to cut down their budget on computer power supply and get the cheapest one around. If you really care about your computer system, you have to put in some serious effort to choose the best power supply.

The computer power supply is the energy source for the whole computer system. Imagine that you are not eating well for every meal, do you think you can still function well for all your daily tasks?

Power Rating

While people are discussing about the gigabytes of storage, 64 bit processing capabilities and the heavy-duty 3D graphics card, the only thing that required the most attention, but is discussed least is the computer power supply. What they have not realized is that the more powerful a computer become, the more power it needs. If you are building a high-end gaming computer, chances are you may need a 600 - 650W power supply.

Mean Time Between Failure (MTBF)

This refers to the lifespan of the power supply. It represents the average hours the power supply can perform before it fails. Most power supplies will have MTBF ratings of 100,000 hours or more.

Short Circuit Protection

When choosing a computer power supply, make sure that it is equipped with a short circuit protection feature. This is to prevent the computer parts from drawing excessive currents which might cause its internal chips to be burned.

Low Noise

The main reason for a power supply to be noisy is because of its inability to dissipate heat fast. The fan has to work extra hard to maintain the required temperature. When choosing a computer power supply, make sure that it comes with a big powerful 140mm fan or two 80mm fans to effectively d issipate the heat away.

Load Current (Maximum and Minimum values)

Each computer part requires different voltage and current to function. It is important that the power supply can support the various voltage levels and the current supplied.

Maximum load current - The maximum current that the computer part can accept for a particular voltage level

Minimum load current - The minimum current the computer part needs to be functional.

If the part is not getting the minimum load current from the power supply, chances are the power supply is spoiled.

Form Factor

Most of the power supplies in the market are of the ATX form factor. However if you are using a micro ATX computer case, you have to get a micro ATX power supply, else it won't be able to fit inside the case.

Conclusion

Power supply is definitely a computer part that you must pay attention to. When choosing a computer power supply, always get a power supply that has a higher power rating than what your system needs. In addition, unless you are willing to risk your computer to system jeopardizing power spikes and surges, do not ever scrimp on the power supply.

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