DC current question

[soldiermedic 10+ year member]

This isn't an audio issue per say, but it is related to a job I'm doing. Hey, what are the odds of my frying a circuit board that is rated at 3.42 amps if I run 3.9 amps into it?

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[basscort2009 5,000+ posts]

is there a fuse inbetweeen it? if not it might damage the board

 

[DBBOOM 10+ year member]

This isn't an audio issue per say, but it is related to a job I'm doing. Hey, what are the odds of my frying a circuit board that is rated at 3.42 amps if I run 3.9 amps into it?

That would be operating at 115% of the devices' intended current. Are you going to run it continuous or momentarily? Heat dissipation would be the main issue.

 

[soldiermedic 10+ year member]

maybe 1-2 hours at a time.

 

[TheyDontWant 10+ year member]

what is the device?

if its a 12volt circuit, and you're only giving it 12volts, its only going to draw 3.42amps...

those current ratings you've listed are common ones for laptop powersupplies, am I correct?

 

[soldiermedic 10+ year member]

yeah, and the board is basically that.

 

[TheyDontWant 10+ year member]

yeah, and the board is basically that.

if you're giving it the voltage it requires, it won't draw anymore current than it needs.

 

[soldiermedic 10+ year member]

if you're giving it the voltage it requires, it won't draw anymore current than it needs.

As long as I ground properly for the excess?

 

[TheyDontWant 10+ year member]

As long as I ground properly for the excess?

what? :S

there is no excess...

by your logic, connecting a car amplifier with a 20amp fuse to a car battery that can supply 500amps, the amp will (for whatever strange reason) draw 500amps.

thats not how it works!

if your mini PC? needs 19volts, at 3.42 amps, then the minimum powersupply you should use, is 19volts at 3.42 amps.

there is no maximum! you could supply it with 19 volts at 1000000000000amps, it will still only draw what it needs!!! which is 3.42amps maximum...

 

[Cabin_Pressure 10+ year member]

if you're giving it the voltage it requires, it won't draw anymore current than it needs.

And if you can somehow up the voltage slightly, it will reduce the current proportionately.

 

[Stalin-ohaulic]

And if you can somehow up the voltage slightly, it will reduce the current proportionately.

Common misconception. It will increase the current proportionately. If magically the device knew it was supposed to put out a certain amount of power and that's all it would do, it would decrease the amount of current it drew when the voltage went up, but that's not how it works. The current and voltage fluxuate with each other. They do not magically even each other out so the same amount of power is always put out. When the voltage goes down, the current draw does as well thus limiting the output of the device. When the voltage goes up, the current the device draws does too.

 

[TheyDontWant 10+ year member]

Common misconception. It will increase the current proportionately. If magically the device knew it was supposed to put out a certain amount of power and that's all it would do, it would decrease the amount of current it drew when the voltage went up, but that's not how it works. The current and voltage fluxuate with each other. They do not magically even each other out so the same amount of power is always put out. When the voltage goes down, the current draw does as well thus limiting the output of the device. When the voltage goes up, the current the device draws does too.

that works if you have a resistive load, but you don't.

if you run a 12volt GLOBE off 16 volts, yes, it will draw more current.

but if you run something like a laptop off 22 volts, instead of 18 volts, it will draw less current as it has a regulated powersupply, however, it will most likely also run hotter, so I advise against this!

 

[Stalin-ohaulic]

that works if you have a resistive load, but you don't.
if you run a 12volt GLOBE off 16 volts, yes, it will draw more current.

but if you run something like a laptop off 22 volts, instead of 18 volts, it will draw less current as it has a regulated powersupply, however, it will most likely also run hotter, so I advise against this!

Not applicable. Sure regulated power supplies work this way because they have a set amount of power they are supposed to put out. How many car audio amps have that? The JL slash series.... I can't think of any other ones. For the rest of the amps out there, when the voltage goes up, so does the current they draw thus the amount of power they put out. When the voltage drops so does the current they can draw thus so does the power they put out.

 

[TheyDontWant 10+ year member]

Not applicable. Sure regulated power supplies work this way because they have a set amount of power they are supposed to put out. How many car audio amps have that? The JL slash series.... I can't think of any other ones. For the rest of the amps out there, when the voltage goes up, so does the current they draw thus the amount of power they put out. When the voltage drops so does the current they can draw thus so does the power they put out.

ah, we aren't talking about an amplifier here, as far as I can tell, weren't talking about a laptop, or mini PC.