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Thread: 12V to 5V step down regulator VS. Switching regulator.

  1. #1
    Who am I? HiJackZX1's Avatar
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    12V to 5V step down regulator VS. Switching regulator.

    I have been wanting to test my setup but can't until I have the KVMP switches powered on external power.

    In the past I had two different devices brought to my attention.

    The first is this one. Its a 12V to 5V step down regulator. What I like about this one is that for my install I will only need one. Its rated at 20A and I need 16A.

    http://www.current-logic.com/shop/in...products_id=14


    Then there is a switching regulator.

    http://www.jameco.com/webapp/wcs/sto...0001_212549_-1


    Now my understanding is that the step down regulator lowers the voltage in the form of heat. Are there any other disadvantages to it? How is reliability? A thing I do like is that I would only need one of these and its only about 39.99 after shipping.

    As far as the switching regulator, it puts out less amps, so I would have to buy 2 of them, which is more expense. I wonder though if the switching regulator is better then the step down regulator.

    So I guess the question is, which is better?
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    I think what you are referring to as a step down regulator is actually a linear regulator. Basically, it reduces voltage through resistance, hence the reason it generates heat. As you can imagine, that heat is what makes them inefficient.

    I don't have any experience using a linear regulator for that much amperage but if I had to guess, it is going to get HOT. Like fry-an-egg hot.

    A switching regulator will be more efficent and run much cooler. If it were me, I'd go with the switching regulator, even if you need two.

    Are these for USB hubs in your install?
    Quote Originally Posted by ghettocruzer View Post
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    Quote Originally Posted by Bugbyte View Post
    I think what you are referring to as a step down regulator is actually a linear regulator. Basically, it reduces voltage through resistance, hence the reason it generates heat. As you can imagine, that heat is what makes them inefficient.

    I don't have any experience using a linear regulator for that much amperage but if I had to guess, it is going to get HOT. Like fry-an-egg hot.

    A switching regulator will be more efficent and run much cooler. If it were me, I'd go with the switching regulator, even if you need two.

    Are these for USB hubs in your install?
    No, I have 6 hubs total, but only 3 need to be powered. The Rear PC is powering its own hub, via the OPUS 320. The other 2 hubs are being powered by a 15W OPUS PSU (5V 3A).

    The problem is the KVMP switches. They use 2.6A each. Basically the KVMPs can be powered via USB, but they would have to get it from both PC units, which will strain the PSU. So I have to power them external to keep the PC running good.

    If I want to be exact, the KVMPs will use a total of 15.2A. Before I needed 20 something amps, but I managed to get the rear system to power Ethernet switch and Access Point also. I may be able to use a PSU.
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    Who am I? HiJackZX1's Avatar
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    In fact, a PSU might be a better route. I am sure the KVMPs dont use 2.6A all the time. Reason being is that I can use the 12V side of the PSU to power all my 12V fans. That will take some load off both the OPUS 320 and OPUS 360. My understanding is that fans can use upwards of 11W and I'd rather have my PSU keep that 11W. It would be more expensive, but I would have 12V and 5V regulation.
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    Could also use an inverter. If I am reading this right (Bing), I take the Volts x Amps = Watts. What am I using though? The adapters are for 12V but they put out 5V. Because if I use 5V, all I need is a 100W supply. If I use the 12V number, I need a 200W supply. If I go the inverter route, I can use the original adapters and inverters are easy to get. Seems both the otehr items have to be ordered from China.

    Plus get maybe a 400 watt unit instead of the 200 watt so if anyone wants to use a video game console in the car.
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    What is a kvmp? I know what a kvm is...

    I think you need to use the 5 volt figure for your calculation. The 12 volt is just the adaptor input voltage. The output is what you want to look at.

    5V X 2.6amps = 13 watts
    Quote Originally Posted by ghettocruzer View Post
    I was gung ho on building a PC [until] just recently. However, between my new phone having internet and GPS and all...and this kit...Im starting to have trouble justfiying it haha.
    Want to:
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  7. #7
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    Quote Originally Posted by Bugbyte View Post
    What is a kvmp? I know what a kvm is...

    I think you need to use the 5 volt figure for your calculation. The 12 volt is just the adaptor input voltage. The output is what you want to look at.

    5V X 2.6amps = 13 watts
    A KVMP is a KVM that has a built in USB hub for peripherals. This is how I am sharing the touch screens between 2 computers. It also has sound switching so if the user wants to say watch a movie with everyone else on the 19 inch, they hit a command and the KVMP will allow them to see the PC2 on their screen, but keep the audio on PC1. These things are pretty cool. Without them my install would have been nothing.

    I think I will go the inverter route. The inverter would cover so much more. It would get the dumb KVMP switches out the way, and give me an outlet if anyone wants to use a house hold appliance like a video game system.

    Boy, I sure strayed far away from the regulator idea, lol.
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    The Current Logic unit could actually be a switching type converter. It says 90% efficiency (if it were linear that number would be far far lower) and other similar units in its product line say they are "dc-dc converters" which essentially means the same as switching.

  9. #9
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    Quote Originally Posted by CanuckMark View Post
    The Current Logic unit could actually be a switching type converter. It says 90% efficiency (if it were linear it would be far far less than that) and other similar units in its product line say they are "dc-dc converters" which essentially means the same as switching.
    Thanx for that update.

    I did change a few things. I may just go with the step down regulator. I do not trust the amperage the inverters claim to handle. It seems every site has a different amperage. I think i'll get the step down and call it a day.
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  10. #10
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    A linear is at least 60% inefficient - ie, 7/12 (7volt drop from 12V).
    If running at 14.5V, its (14.5-5)/14.5 = 65% inefficient.

    If it drops 7V@16A, that's 7x16 = 112W in heat.
    If it's 14.5V hence dropping 9.5V to 5V is 9.5V x 16A = 152W of heat.
    And the input current will be 16A to provide 5V @ 16A = 80W output.

    Switching regulators can be 90% efficient - eg; if 6A@14.5V = 87W input for 5A@16A = 80W output => 80/87 = 92% efficiency.



    PS - that linear converter is a "12V/24V to 5V, Step-down, 20A, 100W". I hope the 100W simply means its output, not its thermal rating. IE; 5V@20A = 100W.
    But max V-input if thermally limited to 100W is 10V for 20A, or (5 + 100W/16A) = (5+6.25) => 11.25V maximum for 5V@16A output (as opposed to dropping 112W & 152W at 12V & 14.5V as above).

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