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Replacing a battery with an RC circuit

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Hi all,

I am building a generator that employs a rotor containing magnets spinning past a series of drive/generator coils. The use of the Back EMF generated is the basis of the generator which has already been built and shown to work but I wanted to make some improvements.

The attached circuit shows the design and it uses one supply battery in the 'Feed Circuit'

My query is just that I would like to replace the one remaining battery with a suitable capacitor circuit that will provide the same function as the battery (which is in effect a very large capacitor) such that once the rotor is spun up by hand, and some of the charge generated is stored, then it should continue as normal.

I don't think that it is just a case of substituting the battery for a huge capacitor as some smoothing may be required on both the input and output to it but I am hoping that there is someone who can guide me on the design of a suitable circuit.

Looking forward to any thoughts,


BEMF Generator.jpg
I am building a generator that employs a rotor containing magnets spinning past a series of drive/generator coils.
What drives the rotor?

Hi Jim
The rotor is driven by the coils in a different part of each close approach of a magnet (in the rotor) to the coils. So each stator coil has a drive and generator role triggered by the rising or falling magnetic field and mediated by the switching transistor.

The pulses fed back to the battery, and also on to the output stage, are high voltage and of short duration and I would like to replace the battery with a capacitance system.

It would take a lot of words to fully explain how it works but I hope you get the drift.

It would take a lot of words to fully explain how it works but I hope you get the drift.
I get the drift that this is some kind of "free energy" or "perpetual motion" machine.

I don't usnderstand this circuit. You seem to be feeding 12 volts DC to the coils of the motor / generator thing and to the primary of the transformer. There is no commutation on the motor thing. The DC current through the coils will just try to hold the rotating part in a fixed position. Also you can't feed DC into a transformer. From your description it sounds like an over unity device. Have I understood your description correctly ?

Edit, I have misread you schematic. I had assumed that the bottom connection of the battery was it's negative terminal. I now see it is the positive terminal so the UF5408 diode would not conduct to pass DC through the transformer and motor thing.
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A couple of points:
- a battery is not a capacitor. Although both store energy, one does it by chemical reaction and the other by electrostatic charge. Their energy storage capabilities are very distinct, as are their discharge curves and output impedance.
- I've studied your diagram, and I find it very confusing. You have a red and a black lines which become both light blue when they connect to the motor coils. Also if you don't label the output of hte inverter (+) and (-). it makes it even more confusing.

But as Les says, this looks suspiciously like an over unity machine.
The device is designed to use the transient back emf pulse generated under Lens Law rather than waste it or filter it out. Its not an over unity system since that implies a closed system whereas nearly all systems are open. Is storing the energy electrostatically rather than chemically hard then?

OK so it is storing the energy from the back EMF from the coils around the rotor,
but where did the energy come from that was put into the magnetic fields of the coils?

Partly from induction from the magnetic fields of the permanent magnets in the rotor and supported by the small current (from the battery) in the drive coils during that part of the cycle. Overall the supply current from the battery is replenished by the back emf which itself comes in part from the ambient electrostatic environment. As I've mentioned this is an open system so talk of over unity is misplaced just as it would be with reference to say solar panels.

Anyway, theory aside, I think it would be more elegant to store some of the energy generated electrostatically instead of chemically in a battery. Hence my query.
ok, let me get this straight... you have 5 coils in parallel, and one of those shares a magnetic core with a transformer. the transformer drives a transistor which seems to be interrupting the DC applied across the 5 coils, i'm guessing to give the motor a kick in the butt to keep it moving. the back EMF from the motor is being siphoned off through a diode to charge the battery (which the OP wants to change to a supercap). the battery supplies 12V to the inverter, which generates 240VAC, some of which is the output, some of which drives the transformer, and we get 30V on the other side, which is rectified, and supposedly is going to supply 42 volts to the motor and the battery. so we go from 12V to 42V in the same circuit (i guess that's supposed to insure the supercap/battery stays charged and the motor keeps going).

looks like an overunity machine to me...

ok, lets look at this logically. we take an electric drill to get this thing in motion. we get the rotor moving at 100rpm, and we get up to a 12V charge on the battery/supercap. the inverter produces 240VAC, and to make everything play nicely, the AC is timed to the rotor. on the other side of the transformer we get 30VAC, and the rectifier pumps a pulse into the motor circuit at the right time to give the motor a kick , and then the pulse from the motor's transformer follows up by driving the transistor into conduction. the collapsing magnetic fields around the coils in the motor push against the magnets, so the motor keeps on moving. then the back EMF spikes, and is rectified, and puts more charge on the battery.... except, there's a voltage drop across the diode, and there's current flowing through the diode, so there's a little bit of heat emitted from the diode. working backwards, now, the transistor, when it went into conduction had a slight voltage drop across it and a large current flowing through it, and that generates some heat. the diode that rectifies the 30VAC has a voltage drop across it while there's current flowing through it, and so again theres some heat generated. the windings of the 240V:30V transformer have some resistance, probably 2 to 5 ohms on the 30V side, maybe 20-30 ohms on the primary, plus the iron core's electrons get shoved around a lot by the AC magnetic fields, so in the transformer we 3 sources of heat. the inverter circuit likely has a transformer in it, plus transistors, and other circuits, which all generate some heat. even the supercap/battery has ESR (effective series resistance) which makes for another source of heat. the motor windings also have some resistance, and so they produce some heat. the motor itself has shaft bearings, and the armature has air resistance, all of which create some heat. so, why all this focus on heat? because this machine isn't a completely closed system. when you generate heat, you radiate energy away from the system. once energy is converted to heat, you can't get it back. since heat is being generated while this machine is in motion, the system continues to lose energy, and the machine slows down and eventually stops (and we didn't even connect a load to the output terminals yet). even the wiring betwen components has some resistance, and will convert some of the energy to heat. once that energy is gone, you can't get it back.

when i was a teenager (and there are a lot of people on this board with the same experience), i cooked up a lot of perpetual motion ideas. i only came up with one that might actually keep in motion for a very long time and that would be a huge flywheel in the vacuum of space. eventually it would begin to slow down because space is not a total vacuum. and you could never extract energy from it, because any extraction would slow it down... actually i did once build a device with a very efficient motor, 2F supercap, and a fair sized flywheel. i could spin it up real fast, and it would take 20min to 1/2hr to slow down to a stop. wire resistance in the circuit, and in the motor, plus air resistance on the flywheel eventually drained the energy out of the system. that's why the laws of thermodynamics are so important in understanding how things work. in this internet age, the laws of thermodynamics can also help you keep your money in your wallet, because there's a ton of people out there selling all kinds of "free energy" stuff, and you see this stuff in operation on camera, and it looks so convincing. what you don't see are the things that have been done to make these gadgets work on camera. one guy electrolyzes water, and feeds the hydrogen oxygen mixture into the carburetor of a car, and shuts off the gasoline supply. then he shows an electrolysis cell connected to the alternator in the car, which is making more hydrogen/oxygen mixture. what you don't see is that yes the car is running off of hydrogen/oxygen mixture, but it's from the large electrolysis cell connected to 120V power, not from the little jar connected to the alternator. it takes more energy to dissociate water, than the energy you get back from burning it in the engine.
As I've mentioned this is an open system so talk of over unity is misplaced just as it would be with reference to say solar panels.
If the device has no external energy input (battery or other source), and you expect it to keep running indefinitely, then it is an over-unity or perpetual motion machine, by definition.

That's quite different from a solar-panel which has an external energy input, the sun's radiation.
Since I have not yet got a workable response to my original query of replacing a battery with a capacitive system I will post this last reply with some bullet points:

  • I appreciate where you are coming from but as a professional scientist, I am aware of the 'Laws of Physics' and that energy is lost as low grade heat in a host of ways.
  • The web is awash with fake videos depicting 'free-energy' but there are also groups of sincere and accomplished engineers, scientists and researchers scattered all over the globe who share their work and developments freely with like minded individuals in pursuit of alternative energy solutions. They don't advertise their work for good reasons and some of these are now at the stage of producing commercially available units.
  • By definition, an 'over-unity' device is impossible in the context of a closed system. To put it one way, you can't get more water out of a cup than the quantity that is in it. However, most systems are open unless that property has been engineered out. We don't refer to a solar panel as an over-unity device (we put nothing in and get a lot out) because we are fully aware of where the energy is coming from and how it is getting into our system. With some aspects of electricity there are areas that have been ignored and overlooked and fresh insights are being uncovered.
  • If we remain within our safe boundaries and mindset we will make only small leaps. If we explore beyond those boundaries then great things are possible and can result.
  • The circuit I am working on is one of many being worked on around the globe and has been built and shown to work - I am simply making a modification.
  • I will never put a video of it on a public YouTube channel for reasons that are evidently clear.

Best wishes to all.
A 12v, 7Ahr battery will give you roughly a 4 volts discharge span , which means 28 Whr.
If my calculations are correct (I am at the airport doing this quickly), this equals 100.8 kJ.

Using the capacitor energy formula 1/2CV^2, you can solve for C and calculate the required capacitor size. It will be humongously large.
Thanks Schmitt, you are quite correct but thankfully I don't need all of the battery's energy to be held by capacitors. Given that the present role of the battery is to act like a giant sponge to the BackEMF pulses and to 'tame' them so that only 12V is showing to the inverter, only about 500W is required to be available to the inverter and its output. By my calculations a capacitance of about 6-7F would do and as I indicate in the attached diagram. However I believe that some inductor would be useful to reduce the pulse height (2-5ms duration at up to 1000V) and then some resistance to make an RC value appropriate to feed the inverter. These are the details in particular that I am not sure about.
Capacitor Storage.jpg
If planning to use super capacitors: remember the formula for series capacitors, in your example it would be C/3.

Also super caps require some good charge balancing circuits which add to losses, even the active ones.
How will you do the charge balancing that Schmitt Trigger mentioned?
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