Relay To Switch On Power to PC Peripherals

tom66

Joined May 9, 2009
2,595
I'm thinking in doing about the same thing, but with the diference that I want to use the Molex and the +5v and +12v for supply the current to my speakers and maybe a switch. If my PC power supply have enought watts for all this shouldn't be a problem, or can it be? (As long as the correct voltage is supplied of course)
The 12V rail will provide enough current to most speakers, however, be aware that you're likely to pick up noise on this rail from other PC components. Make sure to filter it well or you will hear a buzzing sound in your audio when things like HDDs power up.
 

eblc1388

Joined Nov 28, 2008
1,542
You *will* need the diode if you are using a power supply rail to switch it on or off or you will damage something in your computer from the ringing back-EMF by the inductive coil.
I disagree.

One don't need the diode if the relay coil is connected directly across the 12V (or 5V) rail.

When user power down the computer, the voltage on the supply will fall gradually and will not result in a high back emf being generated.

A high back emf is only generated when the coil current is cut off abruptly via a switch or a semiconductor and in this case a diode is required or else damage will occur.
 

Thread Starter

sallysensation

Joined Aug 12, 2011
23
i'm not exactly sure what you are trying to accomplish. if you're attempting to power your speakers off the PC power supply using the molex, then you shouldn't need a switch. the power to the molex is turned off when the PC is put to sleep or turned off.
 

vventura

Joined Jan 21, 2008
10
i'm not exactly sure what you are trying to accomplish. if you're attempting to power your speakers off the PC power supply using the molex, then you shouldn't need a switch. the power to the molex is turned off when the PC is put to sleep or turned off.
I was talking about powering a network switch, as another periferic device just as the speakers. Sorry about the lack of precision. :)
 
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