Using PC PSU to power router?

[junktv]

Is there any reason using your computer power supply to power a router is a bad idea?
I was thinking molex to female N coax plug on the back of the case. Put a inline 2 amp fuse on hot to protect against shorts or surges then make a N coax pig tail to the router. The router requires a 12v 500ma power supply that I don't have.

[kaboom]

Re: Using PC PSU to power router?

Yes, but I'd use a 1A fuse.

Don't use an RF connector for power, it's a waste. There are chassis mount "barrel connectors" for power you can use.

These are a good starting point:
http://www.allelectronics.com/make-a...er-Coax/1.html

[junktv]

Re: Using PC PSU to power router?

This is what I grabbed since they were open today.


http://www.radioshack.com/product/in...ductId=2102489

http://www.radioshack.com/product/in...ductId=2102488

[kaboom]

Re: Using PC PSU to power router?

N connector:
http://www.amphenolrf.com/products/typen.asp?N=0

[tmiha71]

Re: Using PC PSU to power router?

Yes, but I'd use a 1A fuse.

+1

And I would add 1 Ohm / 0.5W in serial connection with fuse just in case ...

You did not write, do you mean to steal 12V from PC (same PSU for PC and router), or use dedicated PSU just for router ?

If dedicated PSU for router - not economical, you will have approx 20W PSU idle losses (without router's 6 W) -> some cheap 12V / 0.5A device will be better solution...

[junktv]

Re: Using PC PSU to power router?

Yes using my PC to power the router so both on same.

The router has a resettable fuse on the board also.

[SeanB]

Re: Using PC PSU to power router?

My router is supplied from the UPS battery, as the UPS i have actually isolates the battery from the incoming mains. Nice in that I save the 5W loss of the original wall wart ( which was written 5V 1A but which gave around 9V open circuit and ran pretty close to 100C internally when in use), and the router power supply anyway uses a SMPS inside to generate the 3V3 and 5v rails it uses anyhow, using a regular SMPS controller pair. this is rated for up to 24V, and runs cooler at 12v than it did with the original wall wart, and the capacitors are 25V on the input as well.

[Logistics]

Re: Using PC PSU to power router?

I wonder what the effects are by using a PC PSU which is PWM? Rather than the original, linear supply.

[Uniballer]

Re: Using PC PSU to power router?

I wonder what the effects are by using a PC PSU which is PWM? Rather than the original, linear supply.

What makes you think the original supply is linear? Most wall warts these days are little switchers.

[Logistics]

Re: Using PC PSU to power router?

Oh, did not know.

[momaka]

Re: Using PC PSU to power router?

Is there any reason using your computer power supply to power a router is a bad idea?

Not really.
If your computer is always on or you only use that computer with the router, it makes sense.

I thought about this way back, too, when I had only one computer and didn't really need the cable modem running all of the time. But then we got more computers in the house and a router, things changed.

The UPS battery straight to router idea is also great. Instead of having to convert the battery voltage to 120V/240V mains and then back to 12V, just give it 12V straight instead (well, morel like 13V, but anyways). Brilliant!

What makes you think the original supply is linear? Most wall warts these days are little switchers.

Yep. You will hardly see linear adapters with modern electronics anymore.

[ratdude747]

Re: Using PC PSU to power router?

Not really.
If your computer is always on or you only use that computer with the router, it makes sense.

I thought about this way back, too, when I had only one computer and didn't really need the cable modem running all of the time. But then we got more computers in the house and a router, things changed.

The UPS battery straight to router idea is also great. Instead of having to convert the battery voltage to 120V/240V mains and then back to 12V, just give it 12V straight instead (well, morel like 13V, but anyways). Brilliant!


Yep. You will hardly see linear adapters with modern electronics anymore.

Old linksys routers (pre-vxworks) that drew 1A (as opposed to the lighter .5A vxworks ones) use linear supplies. Some of the earlier vxworks ones do as well come to think of it.

[kc8adu]

Re: Using PC PSU to power router?

my old wrt54g with dd-wrt is running from the ups/solar battery bank.
can hit 15.5v during an eq cycle.no problem in 6 years.i recapped it a long time back with polys.since it bucks to +5 and +3.3 the input is irrelevent within reason.
the motorola cable modem doesnt seem to mind either.
figure 13.5-13.8 at float on most 12v ups

[Uniballer]

Re: Using PC PSU to power router?

Oh, did not know.

You clearly need to spend more time taking things apart

[eccerr0r]

Re: Using PC PSU to power router?

I think my WRT54Gs came with linears. I suppose a way to guess one from the other is their mass. The iron core in the linears make these fairly massive, especially the higher amp warts... Switchers tend to be all very light.

For whatever reason I think the linear wall warts are much more reliable than the miniswitchers... I haven't had many switchers die... but have had zero linears die (if they stopped working, it's more likely to be a cable issue).

Sometimes I wonder what's the advantage of switchers for the product makers. Seems that a large iron core is just not cost effective anymore versus a small switcher? Surprising...

[kc8adu]

Re: Using PC PSU to power router?

advantage is efficiency at no load.energystar ratings and all that.these things run 24/7/365 whether the item is in use or not.lots of vampire loads in the average household.

[mockingbird]

Re: Using PC PSU to power router?

Linear wall-warts and switching A/C adapter bricks are sort of interchangeable. From what I garnered here, as long as the internal components can handle the peak voltage of the wall-wart, it should work fine.

What I don't understand is why some wall-warts have some diodes and a filter cap in addition to the transformer, and some just have the transformer...

For the record, that router powered from the old GE wall-wart I scavenged is still working great and it's been over a year. I've since found that among the wall-warts that do have a filter capacitor, it's usually bloated either because it was a poor quality brand to begin with, or because it is 20-30 years old.

[mariushm]

Re: Using PC PSU to power router?

Those that have just transformer are AC adapters, they output AC voltage. Those with diodes and capacitor output DC voltage. Duh.

Some devices have an extra diode inside for protection inside. If you plug an AC adapter into the socket meant for DC by accident or on purpose, the diode will do half wave rectification and then the input capacitor will fill the gaps in the dc input and the device will work (as long as the ac adapter can provide the current).

[momaka]

Re: Using PC PSU to power router?

I think my WRT54Gs came with linears.

In general, almost all 802.11b routers and most 802.11g routers came with linear adapters. 802.11n routers, on the other hand, seem to come with SMPS more often than not.

Sometimes I wonder what's the advantage of switchers for the product makers. Seems that a large iron core is just not cost effective anymore versus a small switcher?

Better efficiency for the SMPS at no-load condition. Though ,as kc8adu mentioned, routers and other similar equipment like that run on and at nearly constant load all of the time, so it doesn't really matter that much weather you use linear or switching type.

I think manufacturers switched due to cost. Sure a switching adapter has many more parts and requires more assembly steps. But at the same time, copper is quite expensive these days, so those big old linears probably cost at least a few more cents to make. And then there's the issue of energy "star" and being "green".

Linears are very reliable for the most part. I've seen only a few die randomly (usually primary goes open). Switching type, on the other hand, I've seen fail a lot more. And most of the time, it's a cap related issue - either startup cap or filter caps.