The MintakaFulcrum

Mk 5.0

Feb. 2003

Building Instructions, Photos, and Schematics

Motor Completed March 1st.

New update on this circuit Oct. 20, 2005

When testing this circuit with this motor, the rpm's would climb to a point and then the reed switches would fail by fusing together.. i could not understand this at the time as much as i tried to overcome this problem, I just could not make it work. I thought that the switches were overlapping and that was coasing a 'short' in the circuit and hence switch failure.

But what i was whitnessing at the time, I did not want to believe. What was happening was as the rpm's increased, the current was decreasing. I did not have a very accurate amp meter so it was hard to really measure this at the time. But in retrospect, i could now know this is indeed what was happening.

The rpm's would increase, the current would decrease untill it reached zero, and then would REVERSE POLARITY. At this point the switches would fuse because the circuit was not desinged to handle a backwards flow of energy back to the batteries...

In other words, the circuit was behaving like a true negative resistor... see here

Circut For Re-using the back emf in the next pulse.

Now being vigorously tested .... !

• circuit design that allows the recovery energy to be re-directed to rotor torque in the next pulse via a capacitor.
  
  
  • Preliminary setup indicates that the timing wheel I made is too small and the magnets too week for these big reeds and for adjusting the amount of cycle becomes to dificult to maintain or does not always fire or misfires. Any way, I am going to make a bigger one and try that.
  • A new bigger diameter timing disk did shorten the pulse width but I have found that I have a mis-aligned coil that is causeing a large bucking current back to one of the switches. I have to fix this before further testing.

• April 4 - Everything is back together.
• June 25 - Mk 5.0 abandonded due to reed switch arcing problem at higher rpm.
• June 25 - Switching problem soleved. See Mk 5.1

Switch Details - See Mk 2.0

Rotor Construction Details - See Mk 3.0

Rotor Update

• Rotor strengthened for greater rpm.
  
  
  • I had to find a better way to lock the magnets in the disk so I trimmed a bit of each face of each disk with the lathe. This made the compression fit work great with a little bit of 1 mm foam type two-sided tape. I also took the magnets and rounded them a little bit on the grinder to better fit the curve of the rotor. Be VERY carful if you ever decide to do this and use lots of water. These magnets are just ceramic and not as volitile as NIB's I believe.

Here you can see the small gap between the two halves that allow for a good press fit from the four bolts.

I counter-sunk the back nuts too.

Stator Construction Details - See Mk 3.0

Motor Circuit Details - See Mk 4.0

Assembley Details

Here is the beginning of the frame with all 8 side pieces cut out and placed for fit.	Pieces fit and drilled. 16 threaded rods are added for great strength.
Bearing mounts, rotor, and one coil are installed here.	All eight coils in place with the rotor.
Closeup of the circiut wiring.	Top rear view of the completed unit.
The back showing the timing disk and the two reed switches.	Closeup of the timing magnets and two reed switches.

Mk 5.0

Feb - March. 2003

Test Results, Discoveries & Conclusions

• Test Results
  
  
  • So far draws 200 ma per battery at ~12.5V average. ~5 watts input electrical power
  • rpm=~1,200
  • Tests halted due to switchng problem.

• Discoveries
  
  
  • See Mk 5.1

• Conclusions
  
  
  • Incunclusive - except more power and torque is noted.

CAUTION: The information here is for educational purposes only. Any attempt at replication is done at full liability of the one replicating it. These motors can develop high rpm and high voltage depending on how they are designed. Build and operate at you own risk!

email me: motorlab@shaw.ca

For the copy-right/claim© 2001-5 by: Ian Coke-Richards and The MintakaFulcrum and may be freely distributed with due respect. Not for commercial purposes without permission and licence from the author. All commercial uses are subject to the terms of the user licence.