Slooooow but steady progress. Upgraded bearings will need be found eventually but getting the process set up is my first goal.

Want to say- I am pleased to see so many builds going on this.

I finally sourced a free elliptical exercise machine which I am hoping has a decent flywheel in it.  Just gotta get my arse across state lines to pick it up.. 

Keep it up fellas. 

Brad have there been changes in your design since the last time I worked on this?

Hi Jim.
No, it is much the same.
The only change is the coil triggering system.
I now use a hall switch to switch on the transistor. I just glued 4 small PMs on the flywheel to trigger the hall.
This removes all those blades we were using in the opto interrupter system.

I see in your last video, you got down to just 7mA draw, with all those big blades attached to the flywheel.
Was that including the recycling of the inductive kickback ?, or was that just been burnt off ?

Brad

Remember TM's coil is 5 ohms as is mine. Another one I had was 1.5 and would take 3 amps easy at 30 volts and gave little pull factor. The on I have now is very close to the pull of the mags. Need a scale to set the wattage needed. I would bet your coil is say .5 ohms.
thay

Remember TM's coil is 5 ohms as is mine. Another one I had was 1.5 and would take 3 amps easy at 30 volts and gave little pull factor. The one I have now is very close to the pull of the mags. Need a scale to set the wattage needed. I would bet your coil is say .5 ohms.
thay

My multimeter is saying about .6 ohms so you were right. I need to watch those videos again. I just need to mount the scale then I can finally start some tests. I have a new found respect for how fast tinman puts together his builds.

When making your coils, please keep the turn number high.
I will show you why here-->

Lets say we have a coil of say 300 turns, and it has a resistance of say 6 ohms.
This coil will draw 2 amps at 12 volts= 24 watts.
Magnetic field strength is determined by amp turns, and in the above case, we have 300x 2amp turns=600 amp turns.
If we wind a coil with say 600 turns, and it's resistance is 12 ohms, will still have the same amount of amp turns--600 amp turns, and
 so our magnetic field strength is the same, only in the later case, we are now only using 12 volts @ 1amp= 12 watts of power.
We have halved our power consumption, but maintained the same magnetic field strength.

Don't worry about coil inductance too much, as the inductance of the coil increases as the torque plate gets closer to the coil core.
This is the reason the peak current flattens off at around 2 amps, regardless of the time period, as shown in previous videos.

The early versions of this motor used opto interrupters to switch on the transistor.
My later versions of the motor uses either reed switches, or hall switches to fire up the transistor.
This allows for better switching, and the elimination of large opto interrupter blades, and the power supply for the interrupter circuit.

Brad

Magnaprop

Got a coil wound up. Getting close to having it all mounted so I can add some power. Any last recommendations on how to power it up without burning stuff up?

One important aspect is the pulse time period.

When the current starts rising in a coil the magnetic field starts expanding. When the magnetic field is done expanding all the current starts generating heat in the resistance of the coil. We call this "flat lining", if we watch the current flow on a DSO it starts rising and when it flattens out it starts generating heat.

I often use a voltage sensor, current sensor and a hall effect magnetic field sensor attached to my DSO when tuning coils. This way we can tell how effective or efficient our setup is. Our goal is to produce the strongest magnetic field using the least amount of energy. So it pays to know how strong the magnetic field is and what it's doing relative to our input. 

AC

Still here, sharing some progress. Got a 10gk lifting weight and machined 7kg out of it.. its 27cm diameter.