Circuit setups for pulse motors

[capthook]

Hello!

Here is some detailed info in reference to the Muller generator design.  Some new/different/interesting design ideas are presented for coil construction.
I?m very interested to hear comments on aspects of these coils. (and on my previous posts  )

- - - - - -

By using a core that is basically hollow with only a small amount of metal - such as a tube versus a solid rod, there is less steel to attract to the magnet, but the coil can still produce a great deal of voltage and current. (same idea as hoptoads)

The coil core is equal to the diameter of the magnets. The wire is wound around this core. For example for a 1" diameter magnet, then the core will be 1" in diameter, and the wire will be wound around that.

The Coils are wound on 1" diameter Amorphous Magnetite cores which minimize losses by hysteresis and heat generated by Eddy currents common in other core material choices. The Magnetite is a fine (350 mesh) powder which is mixed in a ratio of 70% Magnetite / 30% Fiberglass Resin to form solid round rod-shaped core slugs upon which each coil is wound.
Magnetite ((Fe3O4) is known by a variety of names. Black oxide of Iron, Magnetic oxide of Iron (it will stick to a magnet), Iron(III) oxide, Loadstone (an impure form occurring in nature and used as an Iron ore). It can be purchased from Ceramic supply stores as black Iron Oxide fairly cheaply.
(source for this material??)

All Coils are wound with 52 turns of  #12 Magnet Wire in a conical fashion which flare away from the Rotor to minimize the effect of magnetic drag on the Rotor's RPM as current draw from the generator increases.
(#12 sure is large! And 52 turns isn't very many!)

A unique zero resistance core design where an increase in the current required by the load results in no resistance to the magnet motion past the coil core, the design for a normal solenoidal coil has the wire wound from top to bottom and as the magnet passes the coil, the resistance to its passage increases as the load current requirements increase.
This new design has a core where the winding begins roughly 1/3 to 1/2 down the length of the core and the windings increase in turns as it approaches the bottom of the core, taking the form of a cone with the apex pointing up,
(seems like a waste not having wire on the top third?  But the reverse cone may be a good idea?)

[hoptoad]

A unique zero resistance core design where an increase in the current required by the load results in no resistance to the magnet motion past the coil core, the design for a normal solenoidal coil has the wire wound from top to bottom and as the magnet passes the coil, the resistance to its passage increases as the load current requirements increase.
This new design has a core where the winding begins roughly 1/3 to 1/2 down the length of the core and the windings increase in turns as it approaches the bottom of the core, taking the form of a cone with the apex pointing up,
(seems like a waste not having wire on the top third?  But the reverse cone may be a good idea?)

Hmmmmnnnn.........Very interesting  ...  KneeDeep !   

[capthook]

Wrapped and tested pickup coils today (6 different).  Being a newbie at it ? I did it by hand as drill winding ended up with sloppy results.  As long as that takes ? I?ll have to just practice the drill winding!!  Masking tape used between layers ? if for no other reason than it made it easier to keep things neater.  I?ve got more designs to try ? but here?s a couple of the results.  Voltage induced given as a reference. 

Air Core:  .2 volts.  300 turns #30 wire.
Crap!  Easy to wind though ;-)  And no drag.

Standard coil:  .4 volts.  40? # 22 wire.  Core: 3/8? x 3? hex bolt.  Windings 1? L x ? W.
(edit: I forgot resistance - 1 ohm)
Getting coil close enough to create better voltage created large drag.

Hollow core:  .6 volts.  70? #26 wire.  Core: 3/8 x 3? anchor sleeve.  Windings 1? L x 3/4 W.  Core flush with windings at the face. (edit: resistance - 3 ohm)

Best voltage.  Lowest drag.  The hollow cores definitely offer superior performance if for no other reason than reduced drag allow for a decrease in the air gap.

Conclusion for today:

Hollow cores ? or at lease thin tubing filled with something like a powdered iron mixture will offer superior drag reduction offering higher output over a solid core. (thanks hoptoad!!!!)

Not sure on ideal wire size ? as I used different sizes ? guess that?s for another day?..
Thinking #24 might be the sweet spot. (I don?t have any!)

Keeping the core flush with the windings rather than extended appears to offer performance gains as well.  An extended coil "heel" "probably" offers benefits as well.

On the hollow sheaths I used:
They are a ?generic? brand ? unsure of composition ? I?ve been unable to locate the ?Ramset? brand ? even on the internet (anyone know where??)   However, they are silver in color ? rather than copper looking ? and they are two separate pieces rather than one piece like hoptoad shows.  A hunch would be the Ramset composition would be superior ? but ? the two piece construction may offer additional eddy current ?dampening? over the one piece?  (Hmmm - then again - this might move the bloch wall further into the center reducing induction.  Even combined as 1 piece via tape/solder/welding etc. ?? )

Hoping for some input??..

Guess I?ll wind/test some more tomorrow?..I'm thinking shorter and fatter.

[casman1969]

@ CH

Muller style coil is 1 to 1, core to magnet...
Adams style is .25 to one. This is what I'm using and it works great.
Hollow core is giving great results for my drive coils. Bifilar wound.
Center tap on drive coil is tied together and I use this connection with a single diode to feed the charge cap. Charge cap reaches > 17V before dumping to battery. I'm sticking with hollow cores for now and when time allows, will use the same for additional pickup coils.
Drive = 20 AWG +/- 5 ohms per winding X 2 (bifilar)
Pickup/generator coils will be 24 AWG. Will try single and bifilar on these as well and will have to test for best size. This is how I will utilize the aditional torque this motor has to offer.
Also something to think about would be having one drive in push and the other in pull mode. That way I can take the center tap and effectively double the output to the cap. Still working out the mechanics of that setup but I'm sure it will involve more reeds. Timing is everything!
Another thing is determining the length of the coil. The best I've found was on the Adams motor site and is quite simple. Put your magnet on a smooth level surface and use a paper clip. Move the paper clip closer to the magnet and mark the spot where the magnet picks up the clip. This will be your true field strength. I'm using N40 Neos 2 X 1 X 1/2 (72 lbs pull force) and found the length of my coils to be 4". Hope this helps.


Carl

[capthook]

Carl - thanks for the excellent info!!

"Muller style coil is 1 to 1, core to magnet...
Adams style is .25 to one. This is what I'm using and it works great."

I was already compromising with a 3/8" core as my mags are 3/4" diameter. (.5-1) - I guess I'll try .25-1 the less metal drag the better!  I'll post the voltage comparions between the two.

"Hollow core is giving great results for my drive coils. Bifilar wound."

What are you using for your coil material?  My next winding I'm going to try bifilar with #22/#26.
Is the "face" of your core flush with windings or extended?  Seems to me flush is better....

Are you doing DC (N/N/N) or AC (N/S/N/S)?  If AC - I guess you're rectifing before cap. (sounds like it)  Are the coils wired in series before the bridge?  And shouldn't you use a full-bridge to utilize both cycles?

I read something somewhere for the 1st time yesterday - with N/S mags (AC)- your coils need to alternate in winding direction if connected in series. ie: coil 1 clockwise - coil 2 counter-clockwise.  I've never heard that and don't know if it's valid.....

Also - I'm using silicon based full-bridge rectifier (Radio Shack 276-1152).  I've read this creates a .7 volt loss where as a germanium material is only .4 volts.  Where to get this better rectifier?

"Charge cap reaches > 17V before dumping to battery."

How are you controlling this?

"Another thing is determining the length of the coil. The best I've found was on the Adams motor site and is quite simple. Put your magnet on a smooth level surface and use a paper clip. Move the paper clip closer to the magnet and mark the spot where the magnet picks up the clip. This will be your true field strength. I'm using N40 Neos 2 X 1 X 1/2 (72 lbs pull force) and found the length of my coils to be 4". Hope this helps."

I had somehow forgotten this!  Of course I should utilize full field of these strong magnets! 
Doing this gives me 1 3/4" - thus 1 3/4" winding depth with a matching 1 3/4" "heel" (total 3")  Guess I need to add some depth to my windings!  Your coil length of 4" - if I'm reading correctly - this is the winding length.  Are you employing a "heel" beyond the windings?
(edit:  I'm not sure how the "heel" /wire/bloch wall depth relate to each other and affect performance...ie: adding a heel reduces coil depth requirement as the bloch wall (magnetic center) is drawn outwards via heel)

(edit): I see you're using reed switches.  Have you considered Hall or optical switching?  Seem to be a more elegent/efficient design.  I've got optical switches to hook up - thinking I'll like that best.
Can anyone provide details on comparions of Hall vs. optical?  (voltage losses etc.)

And yes - this info has been a tremendous help.  Thanks so much!!

(please let me know your core material  )

CH