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Schematic for idea

Hi there, When I was very little I came up with this idea for a power station and I recently remembered it and was curious about the viability. The way it works theoretically is that a voltage supply is temporarily provided to an electric motor to get it spinning up to speed. The motor has a magnet on its armature that spins in a coil to generate electricity, this will generate output electricity. This output is taken from the generator and split, some will go as an output from the power station and some will be fed back in to the system. The portion that is fed back runs through a rectifier to convert it from ac to dc voltage and then through a dc amplifier to get it up to whatever the voltage supply to the motor initially was. The output of the amplifier then becomes the new power supply for the motor as the temporary voltage supply is cut off using a switch. This could potentially leave the system self sufficient. I understand that a small amount of electricity would still have to be used to power the amplifier and it won't be greatly efficient but it was just an idea that I had when I was little. I highly doubt this design will work but if anyone could explain to me why or provide improvements to the design then I would be very grateful.

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    $\begingroup$ You're right - it won't work. Taking electricity from the coil takes mechanical energy from the spinning part - drag - always at least as much (i.e. really, more) than you put into the motor. $\endgroup$ Apr 28 '17 at 12:52
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For pretty fundamental physical reasons any power generator is only a way of converting one sort of energy to another ie converting the energy you have available to the sort of energy that you want. For example :

  • Chemical energy to mechanical power eg an internal combustion engine
  • Mechanical power to electrical power eg a generator
  • Chemical energy to electrical power eg a battery
  • Electromagnetic radiation to electrical power eg a solar panel

Even for sustainable energy sources you still need an ultimate energy source (in many cases this ends up being the sun).

What you can never do is get more energy out than goes in to the system. Again there are fundamental and well proven general reasons why this is the case and finding a 'loophole' in these basic laws of nature, while technically not entirely incredible, would require extraordinary evidence to be credible.

In fact these conversion processes will always waste some energy and even if you can make a system with very tiny losses any energy you take out needs to be replace otherwise you are just storing energy not generating it. For it is certainly possible to design a flywheel with very few frictional losses eg by using magnetic bearings and running it in a vacuum and this may indeed be a useful way to store energy but you can still get out no more than you put in.

In this particular case the thing you are missing is that an amplifier doesn't multiply electrical power, essentially it allows a low powered signal to switch/modulate a high powered output but you still need to put in as least as much power as you get out.

See also

Laws of thermodynamics

Perpetual Motion

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In general, it is not possible and it will not work because of law of conservation of energy. For every energy conversion, you will lose a bit of energy. You can invent many similar circular schemes, for example, solar panel - the light bulb, motor - generator, weight going down and from the energy getting from moving down, going up again, water going down and making electricity and pumping it back, etc. All of them will have the same problem with energy conservation.

More technically: Let's say your motor needs 100 Watt power. When you generate electricity from the rotation of magnets, you will never get back 100W. Let's say you will get 95W. When you use an amplifier/transformer, there are 2 options:

  • if the amplifier/transformer is passive, then you lose anyway. For example, you send your 95W to an amplifier/transformer. 95W was voltage 9.5V and current 10A. Passive amplifier/transformer will increase the voltage from 9.5V to 20V, but current will be decreased and total power will be less for example 90W (20V and 4.5A).
  • Active amplifier will need extra energy, for example, you send to it 95W, it consumes from another source 10W and it gives you back 100W. 5W is lost anyway.
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An amplifier doesn't increase power for free. It takes a signal with not much power, and a power supply and outputs a signal with lots of power. The extra power (in fact, usually all of the output power) comes from the power supply.

Where is the power supply for your amplifier? That is what is powering the whole system. You may as well connect it directly to the output.

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