Electronics Power - Switch and Router

Hi,

I would like to power a router and a switch from my PC's internal power supply.

My PSU is only 120W and has on the label:
Input:
200-240Volts | 4A/2A | 50-60Hz
Output:
+5V(11A) | +3.3(11A) | +12(3A) | -12(0.15A)
+5.05VAXU (2.4A) | +3.3VAXU(1A)

The router power supply says:
12VDC / 1Amp
The switch power supply says:
9VDC / 500mAmp

Am I correct in thinking the router could be powered simply of a HDD molex connector? or would I need some sort of circuit?
The switch I take it would be more difficult, how could I get the 9V/.5A required?


Thank you.

 

The router and switch will use half the supply's +12V 3A capacity. Is that a good idea?

With a more suitable 12V supply, a 9V 1A regulator will do nicely, LM7809 or similar.

 

just do what i did. put a power bar inside your case, and hook up the router and switches ac plugs to it. and your pcs too, that way you plug in the power bar and everything works.

 

not from that PSU, didnt even think they want that low...

 

The PSU is only connected to Motherboard and 1HDD.
No Floppy or CD-ROM's (not even a keyboard or mouse). So I think the 120W should just be enough.

I've linked up the router to the 12V (Yellow/Balck) on a molex connector and it seems to be working just fine.

Now i've just got to link up the Switch. I'll do some reading on LM7809 and see how far I get.....

 

fair enough, the LM7809 is easy as pie, just get one (if uk use rapidelectronics for instance) and a 1Uf cap (Electrolythinc) to smooth it out (probably wont need it as pc power supply = smooth anyway)

with the 7809 facing you (so you can read the text on it) the pins are (from left to right)

INPUT GND OUTPUT
input goes to yellow on molex (12v) GND goes to black on molex and output goes to your switch. Gnd of switch goes to GND on molex
cap if needbe goes between OUTPUT and GND. (polarity sensitive)

also, get a small heatsink as 500ma will meke it too hot not to have one!

 

You can also use the PC's case as a heatsink as the mounting tab is grounded anyways.

 

Hi,

Thanks all for your help.

I've done a stupid little digarm of what I am going to do (as bigal described)


(I could have used circuit diagram symbols - but its more fun this way)

I can get hold of only 16V/10μF Caps and 10V/100μF, can I use these insted of the 1μF cap you suggest.

Also what do the different voltages on capacitors mean? Is it the max voltage they hold (untill they pop)?

Thank You for all your help.