I got the system up and running with the L6388.
 Works like a charm.

 I never quite understood
 why the Aussies were claiming a minimum of two
 sparks at high RPM until I looked at the signal
 across the 2.5 ohm resister in series with the 1 uF
 cap. This resister is simulating the coil,
 for now, in the low voltage (12V) test set up.

 With  12 volts I am getting a peak current
 of .4 AMPS!! through that resistor when the lower
 FET turns on and ANOTHER .4 AMPS!! when it turns
 off. This is due to the totem pole configuration
 of the FET switches. Most CD system use only one
 switch.

 Imagine what the current would be with 300
 volts. Of course the inductance of the coil
 will make  a difference.

 In this set up these two current pulses are 20 usec
 apart. The pulse width and timing are controlled
 by the ZBasic computer with a simple BASIC
 program. RPM is about 9500. The final version
 of course will be stand alone with no
 computer needed.

 Here is a scope picture. The upper
 trace shows what the upper FET switch's
 input trigger is doing and the lower trace
 is the +/- 10 volts across the 2.5 ohm
 resister. E = I x R and I = E/R.

 In other words when the lower FET
 turns on the current pulse in the coil flows
 one way and when the lower FET turns off
 the current in the coil flows the other way.
 Duh!

 This means we will have a total of 8 ignition
 sparks for each leading spark plug. Groups
 of two 10 degrees apart from 22 deg. BTDC
 to 10 deg. ATDC. Up to 11,000 RPM or more.

 Next step is get the high voltage power
 supply and the stock Mazda 2nd gen coil
 working. I'll be very surprised and disappointed
 if this system does not significantly improve
 the BSFC of the rotary.


 Hello Paul;

 This looks like a nice design.  Relatively simple and I
 like the pulse pair with each trigger.  Even closely
 spaced pulses should increase your probability of getting
 a good burn started vs a single spark.

 But be careful when you choose the 300V supply.  Some
 quick calculations based on the energy stored/dissipated
 in the 1uf capacitor shows that 90mJoules is consumed for
 each pulse pair produced. ( energy, in Joules, stored in
 a capacitor is CxVxV/2 )   Each of the two pulse pairs
 uses the same energy.


 At 10k Rev/minute that translates to:
 10k/60 pulses/second x 9E-2 Joules/pulse= 15 Joules/second or 15 Watts.
 That's for one pulse pair per shaft revolution for one spark plug.

 Multiple by the total number of pulse pairs (you always get a pair)
 you will use per shaft rotation to get the total DC power
 you will need at 300V.

 Could be a significant amount of power.

 Craig Taylor


 I have a 400 watt 12 volt to 220 volt AC converter waiting
 in the wings :)

 Kind of old tech because of the 50 Hertz. Heavy and large
 but cheap.

 My new 300 volt 30 watt power supplies are
 converting at 120 Khz (120,000 cps).

 ---------------------------------------------

 I did away with the computer and used the actual
 hardware to control the L6388. The pulse width
 is now controlled by the LMC555. One of the neat
 things about this chip is it will not allow
 both switches to be on at the same time (disaster) so
 that eases the timing requirements. The doc is
 not great but fooling around with it will teach
 you how it works. I already blew the top
 off one but they are cheap :)

 I connected a 2nd gen RX7 coil just to see what
 would happen. It looks like it wants a 1 ms wide
 pulse but that may not be necessary or desirable.

 That allowed the coil oscillations to damp
 down after several oscillations. See the
 attached scope picture. Of course it is still
 running on 12 Volts but the time constants
 should be the same. This will vary of course
 and some coils will oscillate faster than others.

 I'll dig up some other coils and try them out.
 If you have any old coils lying around you
 don't need please send them to me.

 About the max we can do with this coil is 8 msec
 (7500 RPM) /36 or 222 usec if my math is correct.
 2.2 to 10 to the -4 or 0.000222222... 222 usec
 I think. We will probably get one or two oscillations
 going down and the same going back up.

 Next step is the 300 volt power. I'll use
 the 400 watt inverter as I don't want to risk the
 expensive power supplies just yet.

 BTW for dyno test I don't need the inverter.
 It will be possible to merely plug this
 ignition system into the 220 volt wall outlet
 found in the shop :)

 Paul Lamar


 Paul, I recall there being a "low inductance" ignition
 coil designed for CD ignition systems.  With the standard
 Kettering system, the energy to produce the spark is stored
 in the inductance of the coil, which makes a substantial
 amount of coil inductance desirable.  With the CD system,
 the energy is stored elsewhere and too much inductance can
 be a problem, as you are discovering.

 Craig Taylor

 Yes I think you are right. Probably the best bet
 is a MSD coil designed for CD systems.

 BTW I just noticed that Klaus (or Paul Lipps the designer) is
 using three Hall Effect sensors spaced 1/4 inch apart. Could he be
 using the same idea? :) In case somebody accuses me of copying
 Klaus's system I did not know about this until yesterday when
 I noticed it on his web site.

 http://www.lightspeedengineering.com/Products/MiniSensor.htm



 "Single systems require only one Mini Sensor.  On dual 4 cylinder
 engine installations, there are two Mini Sensors at 180 degree
 intervals. On dual 6 cylinder installations, a second Mini Sensor
 is mounted 120 degrees from the first."

 "The Mini Sensor consists of two billet aluminum machined halves
 that capture a small circuit board holding 3 Hall effect sensors
 at 0.250? spacing."

 End quote. I don't know what KLaus is using for coils but
 they appear to be off the shelf. Looks can be deceiving:)

 I have seen it many times but I never paid any attention.

 Klaus's excellent results indicates this idea will
 also improve the BSFC of the rotary.



 BTW Craig the output of my 220 volt bridge rectifier looks
 like this.

 220V____    ________    _______
        |  |        |  |
 0V      |__|        |__|

 Do you think I have a bad diode in  that bridge?

 Paul Lamar

 Paul,

Yes, I see what they are doing with the three hall effect sensors and the
groups of 4 magnets buried in the flywheel at 120* intervals (or 180* for
4-cyl apps).  It is important to see that each of the groups of magnets are
located on a different radius.  Each group of magnets aligns with one of
the
three hall effect sensors.  That looks like a good solution for a 3-rotor.
 By separating the hall effect sensors by .0250", it solves the problem of
distributing the spark to the corresponding rotors at the proper time.  It
seems that the LSE would almost have to utilize a separate ignition circuit
for each hall effect sensor.  This would allow the circuits additional time
to recharge before the next firing event.  As I understand it, the LSE
treats a 3-rotor like three one-rotor engines tied together with a common
eccentric shaft.

Mark

A three rotor is equivalent to a six cylinder when it comes
to sparks per rev. The LSE might work on a rotary but I don't
thing so. The design for the rotary is more difficult due to
the much higher RPM.  He has a much easier time of it as the AC
piston engines run one third as fast as the rotary.


Do you know somebody running a LSE on a rotary? I'll ask Klaus
when I see  him again if he has sold any to Rotarians. I think I
would have heard about it from Klaus.

Paul Lamar



Paul,

No, I don't know of any rotaries running the LSE ignition.  But, if I'm
correct in assuming the 6-cyl model uses three separate ignition modules (I
could be wrong), then for a 20b running at 6000 rpm, sparks/minute would be
like a 4-cyl recip running at 3000 rpm (for each module).  Piece of cake for
one spark per, but if he's firing each combustion event 4 times in rapid
succession, that is another situation altogether.

Mark

I think the 4 -cyl equivalent is 4000 RPM. Klaus may run his engine
at 3000 RPM. We must get this working at 11,000 RPM because a lot
of rotary racers run there. I think he is firing at least 3 times
and maybe six times in rapid succession if he has caught on to the
Aussie totem pole configuration. Klaus used to tell me it was firing
continuously but I never got Paul Lipps to reveal how he was doing
that. I at first thought he was using a crt flyback transformer. I
think that is why Klaus calls it the Plasma ignition system :)

Paul Lamar