Hi there, I want to remotely short the pwr pins on my pc to turn it on and I was thinking maybe I could do this with an arduino. I have a uno r4 and I'm a beginner so please don't judge me if this sounds stupid but could I connect 2 of the pc pwr pins which is usually one of them 5V and the other ground to the arduino digital io pins then using the arduino can you allow current to travel between those 2 pins causing the pc to turn on? Would this work or is the only way to do this with a transistor and if yes how can I determine the capacity/level of the transistor needed? Thanks for any help.
The simplest and safest way to do what you want would be to use a relay controlled by the Arduino to short the two pins
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Follow UKHeliBob suggestion, one mistook in the connection can not only fry your Arduino but also your PC.
Opto-isolator?
The problem with using a transistor is that you don't know how the 2 pins on the front panel header are connected. One might be ground and the other might be pulled high with a pull-up resistor. Or one might be 5V and the other pulled low with a pull-down resistor. Or 3.3V.
You could try out each possibility until you find what works, but then others might want to copy your design, but their motherboards don't work the same.
A relay, or maybe an opto-isolator, should work regardless of any of these factors
Before you go any further with this project, please determine if the turn-on is a momentary connection or a permanent connection. I suspect it is just a momentary connection.
I'm almost certain it is momentary. Never come across a motherboard front-panel header that needed anything else.
yes just momentary.
It has to be a momentory switch.
Think about it, you give the on/off button a short press to turn on the PC and a long press to turn it off.
For more details of the requirements of the PS_ON# signal see the Intel ATX12V Power Supply Design Guide.
The PS_ON# signal is the green wire on the main power connector. You connect it to any of the black COM wires to turn the PSU on/off.
You must connect the two power pins of the PC to the two normally open contacts of a relay. With the Arduino board you can also connect an SPI touch screen like the ILI9341, to create a touch button design.
As it is a momentary pulse, it will only be enough for the relay to activate for just a few milliseconds (175 to 300) for the PC to turn on. This time will also serve to turn off the PC.
Remember to configure your PC's operating system so that pressing the start/stop button performs the shutdown function.
Don't worry, in current operating systems, payment can be done by software or by the physical button on the cabinet without any problem.
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