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This has been on my mind for a while. Lets just take any electronics device. Lets say a mobile phone or a laptop. They have fixed voltage and current, but some components needs higher voltage/current or both. At the same time some components drains power (meaning consuming voltage and current), therefore leaving less power for next components. How do they maintain or amplify power for next components to use?

Might be a silly question, but I never got a clear answer to this question. I saw this thing with capacitors and diodes, how they amplify current, but I'm sure that it only works if you have ac power supply.

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    \$\begingroup\$ I don't really get what you mean by "next components to use". \$\endgroup\$ – PlasmaHH Feb 20 '15 at 13:39
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    \$\begingroup\$ Voltage is not "consumed" like that. \$\endgroup\$ – pjc50 Feb 20 '15 at 13:42
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They have fixed voltage and current...

They don't! You have usually fixed voltage and a maximum limit for current. When a part of the phone needs more current, total consumption will increase. Since power is product of voltage and current, the power consumption will increase as well.

When you go over your maximum current limit, your voltage is going to drop. That's how it works in practice. If a system is well designed, then the maximum current limit will be high enough not to be reached in normal operation.

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This is a very general question but I will attempt an answer. Take your example of a mobile phone powered by a battery. We can model the loads seen by the battery as a number of parallel circuits: one for the display, one for the keyboard, one for the controller, one for the radio transmitter/receiver, etc. Each circuit will draw enough current from the batry to power its components. Each circuit will not consume voltage but will drop that voltagtee across its components to ground. As long as the battery can supply the total amount of current, each component in the phone will get what it needs. Gradually, however, as the energy is drained from the battery, its voltage will decrease until it is too low to properly power the phone. At that point the battery must be recharged. Note that there is no power amplification; the battery can only supply the energy that is stored within it.

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  • \$\begingroup\$ I'm not sure I follow this part of the answer:Note that there is power amplification; the battery can only supply the energy that is stored within it.. What do you mean by it? Could it be that there's a no missing? \$\endgroup\$ – AndrejaKo Feb 20 '15 at 14:39
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    \$\begingroup\$ @AndrejaKo You are correct. The "no" was missing. Thanks. \$\endgroup\$ – Barry Feb 20 '15 at 16:08
  • \$\begingroup\$ And when the battery is low enough your mobile ends to don't allow high current circuits to turn on, like your camera! \$\endgroup\$ – Pedro Quadros Feb 20 '15 at 16:27

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