Power Supply Question.

[Ziddik]

so what will happen if i powered a device that needs 5V Dc and 300ma current with a 5V and 5 amperes powersupply?.. Does the device FRY!!!?..

 

[alec_t]

No. The device takes just the current it needs.

 

[Ziddik]

so why is the term over current used for?

 

[carbonzit]

As was definitely settled in that other thread, overcurrent means a load demanding more current than a power supply can provide. (I misunderstood this as well.) This makes sense, as things like fuses in power supplies are sometimes referred to as "overcurrent protection" devices (they protect the supply against excessive current).

Regarding your original question, this is a trivial exercise. All you need to do is think about any automobile. You have a power source which can provide enormous amounts of current (a 12-volt battery can give hundreds of amps, at least for short times), connected to little light bulbs that only draw milliamps. Do these bulbs "fry" when you turn them on?

 

[ella]

Many times you can look at the electronic systems as a water pipes system.
Current is a amount of water that flows through pipe profile at given time (1 second) .
Power supply can be seen as a water tower and it's MAX current is an amount of water that can be taken at time. Now your device is a tap and the actual amount of water you'l take depends on the tap profile and it's opening. At the max opening you will get as much water as your tap can pass but not as much as a water tower can provide.

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USB-I2C, USB-SPI, USB-GPIO, RS232, RS485, MDIO, Ir, LCD, PWM

 

[Jackdaniel]

hi, how to test a transformer using a digital multimeter? I am having problem with CFL and SMPS transformer.. Pls yelp

 

[ella]

Read it's part number printed on the top of transformer find it's data sheet and measure inputs and outputs according to data sheet.

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USB-I2C, USB-SPI, USB-GPIO, RS232, RS485, MDIO, Ir, LCD, PWM

 

[Jackdaniel]

Read it's part number printed on the top of transformer find it's data sheet and measure inputs and outputs according to data sheet.

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USB-I2C, USB-SPI, USB-GPIO, RS232, RS485, MDIO, Ir, LCD, PWM

Deleted Off Topic. Mod

 

[Jackdaniel]

oh crap, i wont post anything here! Oh crap

 

[Nigel Goodwin]

oh crap, i wont post anything here! Oh crap

If all you can post is abuse, then don't bother, Moderator.

 

[Reloadron]

OK, so in conclusion if we have a power supply rated at let's say 5 volts and 5 amps it means it is rated to deliver a maximum voltage of 5 volts and a maximum current or 5 amps. When connecting devices to that power supply if they require 5 volts at less than 5 amps they will run just fine. The device will only draw its rated current from the source (power supply). Much like the battery in an automobile. The battery is capable of supplying hundreds of amps but the automotive systems only draw what they need.

However, if we take that same 5 volt 5 amp supply and try to power a load rated at 5 volts and 7 amps this will create an "over current" condition. The load requires more current than the source can supply. This is where bad things can happen. A good quality power supply will shut down and use protection when an over current condition exist. The voltage out will fold over and drop. Lower quality power supplies sans protection will in many cases just burn up if they are not fused.

Ron

 

[Jackdaniel]

OK, so in conclusion if we have a power supply rated at let's say 5 volts and 5 amps it means it is rated to deliver a maximum voltage of 5 volts and a maximum current or 5 amps. When connecting devices to that power supply if they require 5 volts at less than 5 amps they will run just fine. The device will only draw its rated current from the source (power supply). Much like the battery in an automobile. The battery is capable of supplying hundreds of amps but the automotive systems only draw what they need.

However, if we take that same 5 volt 5 amp supply and try to power a load rated at 5 volts and 7 amps this will create an "over current" condition. The load requires more current than the source can supply. This is where bad things can happen. A good quality power supply will shut down and use protection when an over current condition exist. The voltage out will fold over and drop. Lower quality power supplies sans protection will in many cases just burn up if they are not fused.

Ron

can i power an lED with 2v 5 amp powersupply?

 

[audioguru]

can i power an lED with 2v 5 amp powersupply?

An LED is powered from a limited or regulated current, not from a voltage. 2V is probably too low for the current limiter or regulator plus LED voltage. A resistor can limit the current if the supply voltage is high enough for some voltage to be dropped across the resistor.

An LED does not have a set fixed voltage like a light bulb. The voltage of an LED is actually a range of voltages because each one is different even if they have the same part number.