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Imagine a motor+generator(Nevermind)

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Steven Rice

New Member
I would like to ask you if you could please possibly draw me some schematics for a circuit that has a 5V DC motor that is spinning a 10V DC generator. Yeah, this sounds impossible. But, I have an idea for a generator that might be changing the world.

If I were to draw the circuit, I would have an LED and a small resistor in parallel with the generator. And I would also like to parallel the motor with the generator, with a potentiometer in series with the motor+generator circuit. And, a safety switch in series.

If you can imagine that circuit, what else would you add to the circuit? Should I use some resistive - capacitive ****?

If the generator works as well as I hope, what do you think I should do with the extra power coming from the generator? Just add more resistors?
 

JimB

Super Moderator
Most Helpful Member
If you can imagine that circuit, what else would you add to the circuit?
A diesel engine.

Your idea violates one of the laws of thermodynamics, the one that says (in a Yorkshire accent) "Tha' never gets owt fer nowt"

JimB
 

Visitor

Well-Known Member
Motor-generators are in common use. They are often used to change power frequency; DC to 60Hz, 60Hz to 400Hz.

Sorry to bring up some pesky physics. It's impossible to get more power out than you put in. In fact, due to inefficiency, you can only get 80% – 90% of the power you put in as output.

Let's say you want to drive the motor with 5 volts, and with a speed increaser to get 10 volts out. Let's say you get 10 volts at 1 amp out, or 10 watts (watts = volts × amps). Neglecting efficiency, to get 10 watts out, we have to put 10 watts in. I = W/V = 10/5 = 2 amps. But say efficiency is only 90% (which would be good this system). 2 amps/0.90 = 2.22 amps at 5 volts to get 1 amp out at 10 volts.
 

Reloadron

Well-Known Member
Most Helpful Member
Resistors, capacitors and all other components aside.

Now as you can see nothing has changed since the other forum. You will get the same answers here but let me show you an example of a dynamotor (motor generator). Now granted this goes back to WW II and while efficiency has improved things are pretty much the same.

This is a dynamotor:
Dynamotor.png

Motor on one side internally coupled to generator on the other side. Now here are the specifications:
Power input 28 VDC 1.25 amps output 250 VDC 60 ma.

It's about power here, it's always about power. So we have 28 VDC 1.25 Amp motor. That becomes 28 * 1.25 = 35 Watts. The output on the generator side is 250 VDC 60 mA so we get 250 * 0.060 = 15 Watts. Only about 42% efficient. With any motor generator scheme there is loss. Power Out / Power In is what it comes down to. Place your hand on a running motor or generator. Do you feel heat? That is lost energy.

Anyway it's not just about volts. There is much, much more to all of this. In a perfect world 746 Watts = 1.0 Horsepower but good luck finding any 1.0 HP motor which will only draw 746 Watts. At about 75% efficient a 1.0 HP motor will draw about 1.0 KW (1,000 Watts). That is simply how it is.

If you want to chase this then have at it, it will be a good learning experience. I tried all of it back in 1961 and it didn't work then and it won't work now. I won't dissuade you so have at it. No resistors or capacitors. Find a motor and drive a generator.

I have a 240 VAC 4.0 KW generator laying in my garage. In theory 4,000 Watts / 746 Watts = 5.36 so all I should need is a 5.36 HP source but it used an 8.0 HP engine. Take a good look at generators and the power needed to drive them. There is no free ride. :(

Ron
 

unclejed613

Well-Known Member
Most Helpful Member
Yeah, this sounds impossible. But, I have an idea for a generator that might be changing the world.
a LOT of people have tried this over the years.... i tried it when i was a teenager using two motors back to back with a big flywheel and a big capacitor to store charge.... things like this work, but they eventually run down. the effects of internal wire resistance in the motor an generator loses energy as heat... all rotating contact points (commutators, slip rings, bearings) lose energy as heat, all the external wiring has resistance that bleeds energy off as heat... air resistance of the moving parts bleeds energy out of the system... you can reduce these losses, but the losses will never be zero.
three laws of thermodynamics in a nutshell:

you can't win,
you can't break even,
you can't get out of the game.

or...
there's no such thing as a free lunch,
when you eat, you drop crumbs
ants eat the crumbs (or, the wind blows the crumbs away)
 

shortbus=

Well-Known Member
Most Helpful Member
Come on guys! You mean my idea of having a small motor running a generator to make power to a light bulb over a solar panel to run the motor isn't going to work? I'll show you guys!
 
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