Sharing +5V from power supply

[Brad Lee]

I don't claim to be an electrical whiz- far from it in fact

I'm going to be re-wiring my CP to make things neater, conceal wires, and make it removable. I'll be using 25-pair wire coming from the CP, and going to (1) IPac and (1) OptiPac. I'd like to wire all of the inputs on both boards, which totals 48, plus a +5V and GND, brings me to 50- using up the whole cable

I know I can chain all my grounds to a single point, but can I do that with my power lines also? How many items can I power with a single +5 feed from my power supply?

I think the term wired in parallel is the right one to describe what I'm thinking

                 +--------led
+5V---------+--------led
                 +--------spinner


WOuld this be too much of a load, ie would the leds be dimmer than using independent leads from the power supply?

[Dak-ak]

im far from it aswell, but leds don't draw much currant... you should be able to put many onto one 5v line (i have 4 being ran in my computer off of one molex right now, and im sure it can handle much more)

why is the spinner hooked up to power?

[Carsten Carlos]

Just a small hint - better put a fuse (e.g. 1A) in the 5V-line before going through all the other cables!

This way you won't blow out your powersupply if you have something shorten. My first early testing pcb did blow out the fuse rightaway, and I'm glad that I only had to pay one cent for a new fuse! (And this happened although I'm an experienced electronican!)

[Carsten Carlos]

In additon, e.g. your harddisk draws as much current as approximately 25 LED's, so you have never to worry about it - there'll always be enough power for them. A spinner won't take much also - with a fuse you are always on the safe side anyway. If you don't want to solder I guess you'll get a fuseholder at the carhifi-store.

[Brad Lee]

Good to know.. I'll check into some inline fuses/holders

dak-ak: the spinner needs power for the optics- it's basically 2 leds and receivers that are used for direction and speed, like on the inside of a mouse


Thanka

[seaner]

Your power supply should have the ratings labelled right on it.  Something along the lines of:
+5V     6A
+12V   2A
-12V    0.3A
etc.
Typically all of the 5V leads coming out of a PC power supply all terminate at the same place inside the power supply, so it doesnt matter which one you tap.  The only thing you will have to take care with is the width of the wires you are using (thinner = more resistance = more heat = fire).  If your wires are rather thin, you can always pair them up, or triple, etc.
Also, Carsten makes a good point about fusing the power lines..  PC power supplies are typically fused already, but it makes replacing those fuses much easier when you don't have to disassemble

[Odonadon]

Here's one:

Can I splice either the 12v or 5v from the PS (not sure which one I need yet) to light up my coin bulbs?  This particular wire has already been spliced - had to make it much longer to relocate my CD-ROM at the coin door.  The bulbs will be sharing either 12v or 5v with the CD-ROM.  Will this cause any problems?  Or should I install a switch to use one or the other and not both at the same time?

Odonadon

[Carsten Carlos]

Can I splice either the 12v or 5v from the PS (not sure which one I need yet) to light up my coin bulbs?

Of course, no problem! I was to lazy to add an additonal 12v-line from the PC, so I bought 6v bulbs for the coindoor. (I need the 5V-line anyway for lighting up the LED's)

The lamps I got draw 0,3A each. A 1A fuse should still be enough including spinner & LED's, but maybe you should take a slightly higher value.

[seaner]

The lamps I got draw 0,3A each. A 1A fuse should still be enough including spinner & LED's, but maybe you should take a slightly higher value.

Of course, a 12V lamp will probably draw much less current than a 5V lamp.  Just be careful not to put in a fuse that has a higher rated value than the ratings on the power supply.  Also remember that a 5V bulb that draws 300mA will draw about 700mA at 12V.  As always, just make sure you don't draw more current than the supply claims it can source.. otherwise you either run into voltage drops or fried power supply bits.