The Ossie motor

[Jimboot]

I accidentally dropped a small mag close to my motor. DOH! It has locked onto the rotor somewhere and slowed revs to 200. voltage initially dropped to 1.20 and now is bouncing between 1.21 & 1.20 I am now seeing some the trough pulses without the artefact I saw in earlier post. Now seems stable back at 1.21. What are these bumps?

[futuristic]

You probably have some wire too near to the rotor.

[Magluvin]

Maybe the lil bumps are that small magnet on the rotor


Mags

[gyulasun]

...
The reason I ask is that I know where I can order the coils that Ossie is using, but I would much rather order a spool and make many coils.  Problem is, the coils I wound are not right.  They are 20 guage I think, but when I measure them they are 1.4 ohm each.  Ossies I think was .5 ohm each.  So what size wire has anyone here used and got the desired results?
....

Hi,

Here is a link that allowes a good insight into multilayer air core coil winding details. http://www.colomar.com/Shavano/inductor_info.html

If you enter the 1.8mH (Ossie coil from Jaycar) in the inductor window and click on Generate Results, a lot of useful data will appear in a new window, showing different wire diameters that will all give 1.8mH, with the included geometry for each wire size.
It calculates the coil from Jaycar pretty close: see the 0.84mm wire diameter that gives 0.98 Ohm DC resistance (Jaycar coil has 1.05 Ohm from the 0.8mm wire).  (Thanks to Futuristic for writing the Jaycar coil data.)

With this online air core coil calculator you can figure out very quickly the coil sizes for any needed self inductance, getting wire diameter, length, DC resistance etc.

rgds, Gyula

[futuristic]

I'm using similar online calculator for air core coils: http://www.pronine.ca/multind.htm

Frenky