Spinning Transformer

I need to be able to power a board on the end of a spinning motor. To do so, I need to create a rotating transformer where the primary is on the motor and is stationary while the secondary is on the spinning board. I have a couple small empty wire spools I can use to wind the coils.
I have 22, 26, and 30 guage wire.

When I power the primary, do I just feed the AC voltage in or do I need any sort of filtering or other circuit? If I were to use the DC used to power the motor, how would I change that DC to AC for the transformer?
Thanks
~Mike

Just a thought?.

Have you considered using the rotary head assembly from a VCR?, these use a rotary transformer to transfer the signals from the head - may be worth looking into?. They work at a fairly high frequency, so you would probably have to feed them from an oscillator.

Your primary can be fed with DC as the rotation will provide the change required to generate a voltage. Your primary will therefore be a electromagnet and so could be replaced with a permanent magnet. The secondary needs to be a coil fixed to the shaft so it rotates in the stationary magnetic field. This could be the armature from a motor. Infact a motor will be the ideal way to power your circuit. If you use a 2 pole type that is found in many experimenter kits, then a full wave rectifier connected to the commutator will provide DC. If you use a 3 pole type, as is more common, then a three phase rectifier will give you DC.

If this isn't the solution that you had in mind and maybe wanted a more visually appealing solution then try to build a scaled down version of the disc brake generator used on windmills. You'll find details of such a generator Here. Look at the Pico turbine plans.

HTH

Mike.

I don't think you need to build a transformer between the spinning and stationary boards to provide power to the spinning board. You can connect the positive (or negative) to the motor shaft and then use a slip ring for the other. The only problem with this setup is that you need a capacitor to smooth out any irregular spikes in the supply power. I'm sorry but I can't advise you on where this capacitor has to be placed.

What you want to do is make a small generator on your mator shaft..
the magnets would be stationary, and spinning with your board would be the coils, and full wave rectifier..
Motor RPM ?
voltage & current required for board ?

So lets say I want it to be able to power up even while not spinning.
Then the genorator, magnets, and DC through the primary would not work. It would have to be AC through primary.
Yes, I have thought about a slipring but I would like the project to be as quite as I can make it and having metal against metal might create a constant scraping sound.
~Mike

Edit:
Haven't picked motor yet, RPM unknown.
Voltage needs to be about 5V and enough power to run an ATmega32 and about 20 tri-color LED's.

MrMikey83 said:

So lets say I want it to be able to power up even while not spinning.
Then the genorator, magnets, and DC through the primary would not work. It would have to be AC through primary.
Yes, I have thought about a slipring but I would like the project to be as quite as I can make it and having metal against metal might create a constant scraping sound.
~Mike

Edit:
Haven't picked motor yet, RPM unknown.
Voltage needs to be about 5V and enough power to run an ATmega32 and about 20 tri-color LED's.

Click to expand...

Presumably for a 'propeller clock', or something similar?.

I need to be able to power a board on the end of a spinning motor.

Click to expand...

what can i say.. :roll:

ball barings cod also work.

i seen it on a site.you have two ball barings and one part is coneted to the circuit and the other rotating part is coneted to the PSU.You also need an cap to filter it a bit.

Yes, a propeller clock. I had this project on hold while I was uber busy with school.
ok, if I can find a correct size ball bearing for the motor I dont have yet, I will use that.
~Mike

Have a rummage around over at the nasa site,
one of thier teams is working on this very problem.

Though for ease of implementation , slip rings are a tried and trusted method. Whilst it can be done with an induction field it does make for a lot of work.

If you are careful, and using direct drive, the motor may be disassembled. At this point, you can take power directly from the commutator. The trick is to get the power past the bearing that is on the output shaft of the motor. For this you can bore through the shaft with a lathe or get a different bearing and a spacer and just drill through the spacer.

If you are not using direct drive, then a transformer (or generator) is the only way to go. Even a small, simple generator can put out quite a bit of power (at least for LEDs + micro). I bought some wheels for my wife's skates that have a small generator on the hub (between the bearings), a few LEDs inside, and a controller. Even light rolling by hand on a table will cause it to light and go through its patterns.