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27

It's supposed to look like a passive PFC choke. Real PFC chokes were common in the early-mid 2000s. Those were replaced by active and lighter counterparts on more recent power supplies. Worst passive PFC knock-off I heard about from my friends in China was that the customers associated heavy weight with PFC chokes, so the manufacturers put a large stone in ...


20

Even though it is DC/DC rather than AC/DC, all of the outputs are fully isolated from the input so 100% of the total energy has to go through transformers, the largest component type in the device. To do that the input DC has to be chopped, just like the input AC in the other supply after it has been rectified and filtered. So the only real savings in ...


10

Aside from matching form factor, power supply volume is more or less constant with watts for a given technology level. The power level is the same, so probably they're using the same topology (a forward converter). The transformer will have fewer turns in the primary but made of larger cross-section wire(s) to handle the ~20x higher current with similar I^2R ...


9

It depends on your 9V device and the load on the 3.3V line. You're essentially using the +3.3V to sink current from the 9V device. SMPS supplies can in fact sink current but only if they're designed to do that and plugging something into the output and hoping for the best will usually end up in tears. It may be OK if you have significant load on the +3.3V ...


9

This should be a standard 0.1" (2.54 mm) pitched header. A name of that thing goes along the lines of SIL (single in line) female crimp housing (for the part which goes on the cable) with fitting crimp contacts for the cable. Something like this and this. There are certainly some already confectioned cables out there (like in the picture you posted). I'm ...


8

The product you link to does NOT connect 2 power supplies in parallel. You add a second power supply to pick up particular peripherals, and this product enables that by using the +5/+12 connector from the main supply to turn on the second power supply. You then use the Molex and SATA connectors to power peripherals such as disk drives or graphics cards. ...


7

The 5V rail will most definitely be able to supply the power that you need in your setup. For most ATX PSUs, the +5v rail has the largest current capacity of all rails on the supply. Many, if not most devices will charge as soon as there is a voltage applied to their USB port, so I'd say that aspect of your setup is also good. I wouldn't worry about a device ...


7

The outputs of the ATX power supply are isolated from the mains. The outputs of the ATX power supply are not isolated from each-other. In other words, +5V and +12V output "share" the same ground. Multiple ground pins increase current carrying capacity. I bet, you will see continuity between them if you check with a meter. My information comes from ...


7

The motherboard doesn't turn the power supply on and off. It controls it between a low power standby, where only the 5v_STANDBY line supplies power, and full output. What controls these two states is the (perhaps mis-named) PS_ON# line. Logic on the motherboard, powered by the 5v_STANDBY line, pulls PS_ON# low permanently to enable the power supply main ...


6

The answer, as to many engineering questions, is "it depends". The most cautious advice is that you can allow current to flow from any rail to any other rail provided that the specified minimum output load current (which may be zero) is drawn from any rail. What is the minimum load, you ask? It's specified in the ATX specification. In no case should you ...


6

It depends on the device. You get 24V but the -12V is usually low power. So you could get a reference voltage. You could use it for powering very low power devices. Check the current rating of the -12V line on your PSU. EDIT: If you want to use your ATX PSU to get 24V, you should get a DC-DC boost converter from 12V to 24V. They are cheap and powerful.


6

Yes, it is theoretically possible. But by the time the conversion is done, most of the ATX power supply would have been redesigned. The hard part of it. The hardest change would be the transformer. To give an idea about complexity of an ATX power supply, here's a reference design. There exist ATX power supplies which run from low voltage DC. These are ...


6

A popular trade name or search terms got these are Dupont connectors. Even when not made by DuPont. Universal connectors for standard 0.1" headers. Otherwise they can be found as female to male or female jumper wire. These will often be 1x1 single connectors. Which are used as often as dual connector for what you want. Preassembled to various lengths, ...


5

In these schematics, 110VAC is connected through a voltage doubler schematic in order to get the same 310V DC after the rectifier. These solutions are pretty outdated now. The typical modern PSU is universal and can work from 90..250VAC on the input without voltage selector.


5

The way a PWR_OK works, or at least the ones I have worked with, is by signaling the stabilization of the power output with a certain tolerance. This is used for sequencing purposes (e.g. When 5V line is ready enable the 3.3V PS). This means you won't be able to use PWR_OK unless PS_ON is high first.


5

There is no need for a resistor. Any voltage <0.8 (or ground connection) will enable the psu Refer to ATX12V Power Supply Design Guide section 3.3.2 PS_ON# is an active-low, TTL-compatible signal that allows a motherboard to remotely control the power supply in conjunction with features such as soft on/off, Wake on LAN*, or wake-on-modem. When ...


5

Each of the 3 power rails (3.3V, 5V, +12V) are connected to a fuse, then to a binding post, while the negative binding posts go to ground. This sounds like the problem. Keep in mind, voltages are differences in potential between two points. There's nothing special about ground, it's just an arbitrary point which we pick. It's 0V because the difference of ...


5

Battery with nominal voltage 12V usually is charged with a little higher voltage. If this is lead-acid battery - that voltage should be 13.8 - 14.4V. Computer power supply is definetly not designed to be connected to battery. Partially discharged 12V battery can have voltage higher than 12V. If you connect it to computer power supply - you may feed power ...


5

Neither. It means that you have to use a ATX power supply. The ATX power supply is a standard for PC style computers.


5

Modularity As @helloworld922 and @Ignacio Vazquez-Abrams point out, a thick wire is extremely difficult to handle in the tight confines of a computer chassis (which are getting ever smaller to meet consumer preferences). The power connector is attached to a card which must exit the bend radius within the specified spacing to the adjacent card so there is ...


5

I see no reason why this shouldn't work. ATX power supplies generate a relatively well regulated +5V rail with lots of power available. I am of course assuming your plan is to connect to the micro-USB power port (as opposed to the USB host ports). The only thing to remember is to add a minimum load on the +5V rail to ensure proper regulation. A 22Ω 2W rated ...


5

Isolation is certainly something that requires a certain board layout, AND it makes transformer windings larger. But that's not the point. The limiting factors for size are thermal transport ("cooling") size of transformers / inductors size of capacitors size of power semiconductors For 3., voltage makes a big difference – a 220 µF capacitor that ...


4

It seems that the grey wire has a high output resistance so the more current you source the more voltage drop you get, although I can't explain why it is able to provide about 13mA to LED1 with no drop and then drops to 2.5v with a few more mA. Anyway, the circuit I suggest used two transistors, a PNP and a NPN each driving one led. The benefit of the ...


4

Connecting a load between any positive rail to any negative rail should be fine provided that both rails can handle the current, and provided that the load can tolerate any common-mode noise that may be present. If both rails are positive or both negative then there's an additional wrinkle which is that one will be sourcing current into a positive rail or ...


4

I suspect your problem is lack of connection for the sense lines. If you take a normal power supply, with just separate insulated wires in a bundle, and look at the motherboard connector, you will notice that several pins have two wires crimped together. The larger gauge wire is the actual power wire and the smaller gauge wire is the sense wire. The purpose ...


4

Try to avoid contention It's not a good idea to put the two outputs of the PSU into contention like this (shorting the outputs of the 5V and 5V-SB together). When the PSU is off, you are back-feeding the output of the 5V supply which will draw current from the standby supply reducing the available useful current and possibly damage it over time. It may ...


4

Yes, but be aware that you are essentially redefining ground for your 24V supply to be 12 volts lower than the ground for the other power supply outputs (5V, 3.3V). This may also be true regarding the neutral and protective ground of the AC input. You will need to be extremely careful if you make an electrical connection between your 24V device and any other ...


4

Per this link, the ATX provides isolation from the wall power supply. But their outputs share a common, the link also gives the simplified circuit of a PC PSU. And the ATX standard defined the connector pin-out. There are many "COM"s on a connector, beside the reason for interconnecting, there are reasons to increasing the current carrying capability. ...


4

The order and method to debug and root cause the failure depends on the individuals experience and skills. A multimeter is capable of assisting a root cause analysis process to a great extend, but depending on the complexity of the circuit you need other tools too. I am assuming that you have the electrical schematic diagram, PCB Layout and part placement ...


4

If you want to power a pc from a regulated 12 Volts, you should look into a compact SMPS setup. Or you know, just use a commercial product like a Pico PSU. Completely depends on how much power you need. As far as using Zener Diodes, based on typical ATX current needs, you will need a huge Zener or heatsinking. It's not even close to ideal. Using a Zener ...


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