dumb question volts/amps - how much is too much?

Martin - this router is not a rotary tool - it is a data device.

Not as bad as the piece of Tupperware my wife "cooked" in the electric oven last night... :(

I was wondering about that in the initial stages of reading the OP's message. 12V@0.5A would hardly power a HF mini-Dremel, let alone a real MAN'S router.

-- Age is always advancing, and I'm pretty sure it's up to no good. --Harry Dresden

Think of voltage as pressure and current (amps) as flow rate. The flow rate depends on the load or current conducting path available, just as it depends on pipe size, valve setting, etc in a water supply system. A short presents no resistance to flow, like an open water main, so flow rate will be the capacity of the source. Your half-amp load presents resistance to flow such that when supplied with 12 VDC it will draw about 1/2 amp even if the 12 volt source were capable of supplying thousands of amps, just as a faucet might draw one gallon per minute from an 80 psi water main capable of delivering hundreds of GPM to a hydrant.

True, but as I said above, only if there is no fault in the device. There are some devices that rely on the overcurrent protection in the wall wart. If such a device was powered by an unlimited supply and there was a fault in its circuitry that caused ot to draw lots more current, there could be an exciting event - Ed might find it amusing ;-)

Larry Jaques on Wed, 27 Apr 2011

No, I've got power supplies for those things. Thanks to everybody for the advice.

The router "worked" for some values of "worked". But trying to set up an home network which did not kill off the WiFi access in the process ... I had to go back to he restore point.

(What I'm trying to do is use the WiFi connection on a laptop for Internet access - to neighbor's WiFi router - and then hook the desk top to the Laptop, so that the Desktop can log-on through the WiFi. Microsoft has no clue as to how that might work, so it figures I must mean I want to set up a wireless router connection and the wizard then blithely completely screws things up. But that is a different rant.)

Don Foreman on Wed, 27 Apr 2011

Electricity is like water - it has to have a 'flow' out in order for it to 'flow' in. Hence the number of electricians who will work with one hand in their pocket.

And power Engineers with both hands in their pockets..

Wouldn't that be "hand in YOUR pocket"? :)

I like the water pipe analogy, until it comes to "short" circuits and "open" circuits. ;-D

Cheers! Rich

Correct.

A voltage supply supplies what it wants to put out in voltage up to a maximum current rating.

The load draws what it needs up to a max rating of the supply.

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I've a wall wart which is rated 12 V DC at 1 amp output

The router is (I think) expecting 12 VCD at .5 amp.

And I correct in assuming that the wall wart will not "over supply" the device - that its rating is essentially the max amperage it will output, while the router is the amount it will draw to function?

That seems to make sense, to me. At this hour of the morning.

-- pyotr filipivich. Discussing the decline in the US's tech edge, James Niccol once wrote "It used to be that the USA was pretty good at producing stuff teenaged boys could lose a finger or two playing with."

It's a closed circuit water looped system with a crirc pump or consider the ground as the return.

Fluidic systems have this terminology all backward. Closed valve means an open switch in electricity and verse visa.

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Cheers! Rich

When I was in the USAF, if you were caught wearing any jewelry while working on electronics, even freakin' DOG TAGS, you were subject to disciplinary action.

Actually, I was kind of astonished when I learned that a welding arc drops about 20-30 volts. Consequently, I wouldn't even wear a wristwatch while, say, jump-starting a car.

I was once helping a buddy jump-start his car - I put the cables on my battery, and he proceeded to start to apply the clamps to his battery - red to black and black to red. I shrieked, "NO!NO!NO!NO!NO!NO!NO!NO!NO!" and luckily stopped him in time. Whew!

Cheers! Rich

I was kind of surprised to learn that the fuse in the equipment isn't there for the purpose of protecting the equipment - it's there to protect the supply and its wiring from when the equipment fails short.

Cheers! Rich

One of the things I worked on when in the USAF was a jamming transmitter with a separate power supply. The power supply was pressurized, to maintain breakdown voltage so that it didn't arc over internally. One day, we got one of the pressurized power supplies in the shop that had blown its selenium rectifiers. Hoo Boy! It cleared the whole building for the rest of the day!

Cheers! Rich

pyotr filipivich wrote: [question about volts/amps]

The only "dumb" question is the one you don't ask.

(Unless you ask Mr. Garrison - he says, "There are no stupid questions, only stupid people.")

Cheers! Rich the Philosophizer

Install Linux; it'll be almost trivial.

Good Luck! Rich

Should have been "stupid listeners" on Usenet...LOL

pyotr filipivich wrote: [question about volts/amps]

The only "dumb" question is the one you don't ask.

(Unless you ask Mr. Garrison - he says, "There are no stupid questions, only stupid people.")

Cheers! Rich the Philosopher

Let me guess that you have a D-Link router? My D-links have eaten a number of power supplies until I got a good non-OEM one rated at 2 amps. It'll only draw what it needs but I think it sometimes needs more than the OEM supply can reliably deliver.