Electronics > Beginners
ATX conversion question
shobo:
--- Quote from: rstofer on December 10, 2017, 12:28:00 am ---I'm not sure why you are using the resistor...
Here is a neat way to set up the ATX supply:
https://www.sparkfun.com/products/12867
Notice that the gadget has fuses. This is important because the ATX has far more current capability than you want to have in a bench supply. The magic smoke comes out of chips really quick when the power supply doesn't limit the current in any meaningful way.
--- End quote ---
The shipping will kill me.for the moment an ATX extender and a minimum of 4 banana plugs would be something around 7 dollars + a power resistor for 3 and change.
robotic:
Wow didn't know there were so many options. I was going to do the same type of thing (but cut the wires as I have so many power supplies [salvaged from old PCs]). After buying a used power supply, it's been night and day though. I love being able to see the amperage draw and adjusting the voltage and such. I would get the DPS powersupply for $25-$50USD (depending on model).
However the ATX conversion is great for simple things like powering my 12v lipo chargers so I don't have to constantly disconnect and reconnect things.
SteveSi:
I am also planning an ATX PSU + DPS3005 + USB PSU.
So this gives me all the ATX rails + a variable, current limited rail.
However, I really want the DPS3005 to provide 15V max.
I thus plan to use -12V and +12V from the ATX PSU to connect to the DPS3005 - but will this give me a problem with the earth - for instance, if I connect the ground of my scope to the 'gnd' output on the DPS3005 then will I get magic smoke?
If so, would it be better to get the buck-boost DPH5005 module instead and feed it 12V to get a 0-50V output?
janoc:
--- Quote from: phil from seattle on December 10, 2017, 01:09:19 am ---The resistor is there because most (all?) PC power supplies need a minimum load to start.
--- End quote ---
Most newer supplies have the resistor built-in, so there is no need for an external resistor. It isn't only for starting the supply up but also to ensure a minimal load current in order to maintain the supply in regulation.
The resistor is included in the kit because people often recycle old junk from discarded computers which may not have these.
madires:
--- Quote from: SteveSi on October 14, 2019, 03:25:06 pm ---I thus plan to use -12V and +12V from the ATX PSU to connect to the DPS3005
--- End quote ---
The -12V rail of most ATX PSUs delivers just 0.5A, way too low. The next issue is that the PSU's ground is connected to earth/PE and therefore you won't get an isolated output. And since the -12V rail is going to be ground for the DPS3005 a scope with ground connected to earth/PE would create a short circuit on the -12V rail. Either get a decent PSU or buy the DPH5005 (not isolated due to the ATX PSU).
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