Boosting current on floppy disk DIY Generator?

I tore apart an old floppy disk drive and built a little DIY generator. It is a proof in concept to power a propeller clock.

I am successfully generating around 12 V but only at 4.5 ma. I think that is hardly enough to power the UC not to mention multiple LEDs.

My load was a 220 ohm resistor because that is what I had sitting on my work bench.

I chose the 2200 uf cap because that was pretty much the only cap I had on hand.


Currently I am spinning the generator with an electric hand drill and the mechanical coupling between the drill and the magnet plate is not the best but I do seem to get it spinning pretty well.

I do plan to use a HDD motor to spin everything but unless I can get the current up the generator idea is not going to work.

Any ideas other than to get a bigger generator?

The motor (generator) can not supply more current than its rated current. It will burn.

mik3 said:

The motor (generator) can not supply more current than its rated current. It will burn.

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Yes I guess I sort of knew that. How do I know what the current rating should be? Shouldn't I be able to get more than 4.5 ma out of this thing?

How did you determine the 4.5mA current limit?

What will be turning the generator? Hopefully not the propellor clock.

mik3 said:

How did you determine the 4.5mA current limit?

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Measured it with a ammeter

blueroomelectronics said:

What will be turning the generator? Hopefully not the propellor clock.

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I planned to mount the stator on the bottom side of the PCB that holds the circuitry for the propeller clock. Then build a fixed mount for the magnet. The HDD motor would spin the board / stator and I would pull my power from the generator to power the clock.

It is all just an idea right now. One problem I realize I have is that the clock will need to be spinning to power it. One problem that creates is how to set the time. But I haven't gotten that far yet.

I'd just be happy to get my generator supplying a half way decent amount of current.

spinnaker said:

I planned to mount the stator on the bottom side of the PCB that holds the circuitry for the propeller clock. Then build a fixed mount for the magnet. The HDD motor would spin the board / stator and I would pull my power from the generator to power the clock.

It is all just an idea right now. One problem I realize I have is that the clock will need to be spinning to power it. One problem that creates is how to set the time. But I haven't gotten that far yet.

I'd just be happy to get my generator supplying a half way decent amount of current.

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No you can't have overunity.

blueroomelectronics said:

No you can't have overunity.

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I did not plan to have the generator run the motor and the motor spin the generator Actually I had a friend that was convinced that would work and he was a mechanic!


The generator was just an idea to transfer power to the spinning board. A power supply will run the motor spin the board and stator and produce power for the board. At least that is the idea.

Ask your mechanic where's my flying car.

spinnaker said:

The generator was just an idea to transfer power to the spinning board.

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For the generator to produce power it has to receive power (mechanical power). This mechanical power will be provided by the motor which will be powered by the power supply. The generator will return energy back but it will be less than the energy given by the motor. Thus it will only waste energy.

Well, part of the problem here is that motors were designed to be motors and generators to be generators.

While an old style "permanent magnet stator and brushed rotor" motor would work fairly well in both situations the newer brushless motors weren't designed to do so, they're often similar to a three phase induction motor and to make a generator out of one you've usually got to induce magnetism into the system by running some current through at least one of the windings.

I'm afraid this is what you may be facing, the output you're seeing is coming from a small amount of residual magnetism that the stator or rotor has collected over time.

Either way no matter what motor or generator you choose you can have one powering the other to power itself.

blueroomelectronics said:

Either way no matter what motor or generator you choose you can have one powering the other to power itself.

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That is not what I am trying to do. I have already explained it twice, once to t to you. Once to you directly. Please read it again.

Ahh I get it now. Sorry about that. Try a stepper motor, fair amount of friction but they make decent generators. Best bet is a simple brushed ring to supply the power (how most propellor clocks work)

marshallf3 said:

Well, part of the problem here is that motors were designed to be motors and generators to be generators.

While an old style "permanent magnet stator and brushed rotor" motor would work fairly well in both situations the newer brushless motors weren't designed to do so, they're often similar to a three phase induction motor and to make a generator out of one you've usually got to induce magnetism into the system by running some current through at least one of the windings.

I'm afraid this is what you may be facing, the output you're seeing is coming from a small amount of residual magnetism that the stator or rotor has collected over time.

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The magnet is still in the picture. Right now I am spinning the magnet around the stator but I had planned to spin the stator in the magnet. But you are right, I am using something for which it was not designed. I thing the real issue is the motor (generator) is just not large enough. The magnet on those floppy drives is pretty small.

But really the whole point of a POV clock is getting something to work for which it was not designed.


I came up with another idea. I am thinking I might be able to transfer power to the board using induction. Would a transformer with round coils, with one of the coils spinning work?

Most people power their POV clocks by removing the bearing on one side of the motor and powering the spinning board off of that but that can of course cause the motor to run rough.

Passing a coil over a magnet will produce current. A stationary ring of magnets and a couple of coils might work.

blueroomelectronics said:

Ahh I get it now. Sorry about that. Try a stepper motor, fair amount of friction but they make decent generators. Best bet is a simple brushed ring to supply the power (how most propellor clocks work)

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Yeah I have seen that too but brushes can fail. I was just trying to come up with a different way to do this project. Something sort of unique. Even if it is inefficient.

blueroomelectronics said:

Passing a coil over a magnet will produce current. A stationary ring of magnets and a couple of coils might work.

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That is exactly what I am trying to do with the floppy drive motor. It has a magnet it has a stator. Everything is there except it does not appear to provide enough power.

Try to get your hands on a stepper motor.