<snip
     I also did away with one tooth to better simulate
     what will happen in the final flyaway configuration.
     There will be only one trigger tooth and four mag pickups.
     Two for ignition (about 22 degrees BTDC) and two for fuel
     injection (about 90 degrees BTDC). The angular position of
     the pickup relative to top dead center will adjust the
     timing of both 555 fuel injection and ignition.

     Paul Lamar

Paul -

You crack me up.  Just months ago when I brought up this scenario for
triggering injectors and ignition, you complained that it had too many
sensors, and that sensors weren't cheap.  :)  At the time I brought it up
more as an illustration of the rotary's simple timing arrangement than as a
design proposal.

But hey, I'm glad its value as a simple, no-moving-parts system has become
apparent.

I guess I ultimately agree that it DOES have too many sensors, too much
shielded wiring, and too many critical clearances to set.  A timing wheel
with a simple counter & multi-trigger circuit would be more pragmatic, I
think.

Just my thoughts.

-Vince Orton

Some times it takes a long time for a good idea to sink into my brain :)
There is some redundancy here. If one sensor fails it will only affect one
rotor.

These sensors are expensive. Klaus tells me he took one apart and it had a
zillion turns of very fine wire. He uses tiny rotating magnets and hall
effect sensors instead because they are cheaper. Trouble with that is Hall
effect sensors need voltage to work.

I am looking for a cheap source for these magnetic sensors and I may attempt
building my own. They appear easy to make. Materials are cheap.
You need some magnet wire:

http://webtronics.stores.yahoo.net/32mawi1lbspm.html

A round cylindrical bar magnet:

http://www.kjmagnetics.com/categories.asp?gclid=CJXmz-DonZgCFRwDagoddmh2Aw


And a housing made from steel threaded pipe used in lamps:

http://www.nationalartcraft.com/subcategory.asp?gid=1&cid=24&scid=437

Here are the dwgs and some files.

Paul Lamar


Paul, you might search Ebay for "coil winding machine" there are some fairly
inexpensive machines out there.
Or If you think this will be an ongoing need for our rotary projects, and
you haven't the time, I'll take on the coil project invest in a winder and
some raw materials and start production.
What do you think?
C. Smith


That is a good idea. The need for these things is not going away.
It will take some experiment to come up with a 300 volt coil.
Revmaster did it so it must be possible.

BTW one or more of these things looking at the ring gear would make a good
low cost back up alternator. The magnets do not have to rotate.
They can be built into the coil. All you need are changes in the magnetic
field and the ring gear starter teeth will provide that.

Paul Lamar

I'm on it, should be in production in a week or 2.
C. Smith

BTW Craig I measured the resistance of the stock pick up.
It appears to be 1.2K  Knowing the resistance of 32 ga magnet wire per foot
one should be able to calculated the number of feet of wire required. I
think it is .16 ohm per foot.
If so you will need 7000 feet.
http://www.bcae1.com/wire.htm
http://amasci.com/tesla/wire1.html


Subject: AWG Wire Chart

AWG       D.C. OHMS     WIRE DIAM   APPROX. TURNS PER      FEET PER
SIZE     PER 1000 FT     INCHES     INCH, SOLID ENAMEL      POUND
                                      COVERED
   1        .1264          .2893         X                    3.947
   2        .1593          .2576         X                    4.977
   3        .2009          .2294         X                    6.276
   4        .2533          .2043         X                    7.914
   5        .3195          .1819         X                    9.980
   6        .4028          .1620         X                   12.58
   7        .5080          .1443         X                   15.87
   8        .6405          .1286         7.6                 20.01
   9        .8077          .1144         8.6                 25.23
   10      1.018           .1019         9.6                 31.82
   11      1.284           .0907         10.7                40.12
   12      1.619           .0808         12.0                50.59
   13      2.042           .0720         13.5                63.80
   14      2.524           .0641         15                  80.44
   15      3.181           .0571         16.8                101.40
   16      4.018           .0508         18.9                127.90
   17      5.054           .0453         21.2                161.3
   18      6.386           .0403         23.6                203.4
   19      8.046           .0359         26.4                256.5
   20     10.13            .0320         29.4                323.4
   21     12.77            .0285         33.1                407.8
   22     16.20            .0253         37.0                514.2
   23     20.30            .0226         41.3                648.4
   24     25.67            .0201         46.3                817.7
   25     32.37            .0179         51.7               1031
   26     41.02            .0159         58.0               1300
   27     51.44            .0142         64.9               1639
   28     65.31            .0126         72.7               2067
   29     81.21            .0113         81.6               2607
   30    103.7             .0100         90.5               3287
   31    130.9             .0089         101                4145
   32    162.0             .0080         113                5227
   33    205.7             .0071         127                6591
   34    261.3             .0063         143                8310
   35    330.7             .0056         158               10480
   36    414.8             .0050         175               13210
   37    512.1             .0045         198               16660
   38    648.2             .0040         224               21010
   39    846.6             .0036         248               26500
   40   1079               .0031         282               33410
   41   1323               .0028
   42   1659               .0025
   43   2143               .0022
   44   2593               .0020
   45   3348               .00176
   46   4207               .00157
   47   5291               .00140

************************************************************************
   For winding Tesla secondary coils the general consensus is to use
   number 22 AWG, or larger diameter, double Formvar Magnet wire. Often
   surplus partial spools of odd wire sizes are found, so I took time to
   post a more complete chart of AWG numbers and fractional diameters
   than is usually available.  All information above is approximate
   despite the decimal places. Wire diameter, turns per inch, resistance,
   feet per pound, etc. all vary slightly from one manufacturer to another.
   Insulation thicknesses will vary depending upon type and the supplier.
   Turns per inch will also vary with the quality of the winding. In
   practice, Tesla coil windings are not perfect (nor do they need to be)
   so expect some slight variations from the specification table above.

Richard Quick




Thanks for the valuable information. Does the stock coil generate 300V? Do
we know what it does generate? Helpful in deciding which way to go. One
spool from the electronics source is $28 and 4800 feet. So one would need 2
spools of the 32ga.
That would make for a very large and heavy pickup. I'm thinking we'll need
A)finest wire available, and or B)step up transformer.
Will have to re-do my order with the electronics guys tomorrow, and see if
they have larger spools available and wire of gauge finer than 36.
C. Smith

The stock coil generates plus or minus 15 volts depending on the RPM and the
distance from the teeth. Low current however as the wire is real fine. For
triggering the 555 we don't need much current as the 555 is CMOS.

For a 300 VOLT simple coil connected to a stock Mazda ignition coil one
would need a much stronger magnet and a much larger wire to handle the
current required. This is where the experimentation comes into play.

One way is to rotate a larger magnet inside a cup shaped device on the front
of the e-shaft. As simple coil sees the changing magnetic field and has a
current induced in it. This is the way permanent magnet type alternators
work.

http://physics.bu.edu/~duffy/PY106/InducedEMF.html

Another way is use a much larger cylindrical magnet with a larger coil
adjacent to it  with thicker wire wound around it.
Fundamentally a different device than a simple coil. Attached is a patent on
such a device. This is how the stock Mazda pick ups works.

The last device looking at the ring gear teeth would serve as a low power
alternator.


Paul Lamar


So there you see that this is becoming more than a simple pick up coil, or
something that is "simple" to build, and also may violate a patent. I think
this is why such things aren't cheap, even in mass produced quantities. I'm
gonna stick with the stuff that was earlier recommended before any research
was done, because that's what I committed to. Sounds to me like you guys are
ready to write it off based on the simple observation that it would take 7k
ft of 32 ga wire to equal the stock Mazda coil.
C. Smith

No not at all Craig. 7K of wire may not be at all unusual in a device like
this. If even smaller wire was used there may be less of it to get the same
resistance.

I would not worry about the patent as the patent appears to be a conical
device while the Mazda unit appears to be a cylindrical device. I can
look back at earlier patents and see if the cylindrical device was not
patented years prior. Hopefully 17 years prior. Nobody is going to go
after a cottage biz anyway.

Paul Lamar


I think I'll close with the observation that we can throw numbers around
without really understanding the rest of the story. Yes, smaller wire means
less wire to get the same resistance(lbs/Kft), it also costs more and is
much more difficult to wind a coil with. The smaller the diameter, higher
the cost with a few exceptions (yes, greater resistance, learned that about
3 decades ago) the lower the tensile strength, and thusly the more difficult
to work with. Any of you guys tie your own flys?
I just removed a magnetic pickup from a flow sensor being used in a test
cell. It's old technology, in the 1.5 k range, it is about 4" long and over
1/2' dia. My mistake is not checking the math of suggestions, thinking that
the little things were already looked at, my bad. I should know better.
C. Smith

Well the flow sensor could be the old type with out the permanent
magnet. There are plenty of sensors out there that require a current
to magnetize the sensing coil. The permanent magnet type are johnny come
lately. Is it magnetic? The Mazda types are.

There are two device here. One is a pickup to trigger the 555.
The second is a higher current coil to trigger and power
a stock Mazda 2nd gen ignition coil.  Are you giving up on both?

Paul Lamar