I had to add a .1 mF and a 47K resister. I suddenly realized that in
the remote chance a magnet stopped in front of a hall sensor the IGBT
would stay on and burn out the 1K 25 watt resister or maybe destroy
the high voltage power supply or IGBT. Something would have failed.
The 47K/.1 mF combination circuit is called a half one shot.
It will not pass DC. The engine must be turning over however slowly
for it to work.
That is one thing Hall Effect sensors do that VR CAS sensors do not
do. Not enough however, to not use Hall Effect CAS sensors :) They
put out full pulse voltage at near zero RPM.
Paul Lamar
-------------------------------------------------------------------------
The 8 to 40 volt input 300 Volt DC out high voltage power supply
can be
had
direct from Linear Technology for $125
http://www.linear.com/demo/dc1322a
I bought one and will test it as soon as I get it. I plan on using it
for the RV4 stand alone CD ignition system.
I can make it for less than this.
There are several CD ignition options for a 2 rotor.. In order of
redundancy and cost.
1.One power supply, two CD modules, two waist spark coils. Lowest
cost. 2.Two power supplies, two CD modules, two waist spark coils.
3.Two power supplies, four CD modules, four simple spark coils.
4.Four power supplies, four CD modules, four simple spark coils.
Highest cost.
Paul Lamar
I noticed that the specs for the demo circuit say that 1 sec is
required
to charge at 8V. Even the 400 ms at 40V seems a little long. How
do you
deal with that?
Gary Knutson
Very astute question. Good thinking Gary.
That is an on board 400 uF capacitor so it takes awhile to charge.
However once it is charged it can dump into the 1 uF CD cap rather
more
quickly
I expect. One of the things I want to test.
Paul Lamar
I was hoping there was a solution. I will be watching for your
continuing
tests.
I have been closely following the "CD" thread as I think your efforts
could produce a big advance in aircraft engine ignitions. I may
have a
requirement for a system for another engine (non-rotary).
Gary Knutson
CD ignition module PC board tested.
The movie show the plugs sparking with the waist spark coil.
There is a 2.5K resister in series with the 500 Volt supply so it
takes about 5 ms to charge the 1 uF cap. A smaller resister would
charge the cap faster. The scope wave form period is about 10
or 12 ms so this is 5000 to 6000 RPM. A slightly smaller resister
would be needed for 7500 RPM.
There is room on the PC board and the required circuitry is there
for a
second 1 uF cap which in theory would double the spark energy.
This was tested with the 110 volt wall powered HV supply.
I will test it again shortly as soon as the 12 Volt HV supply arrives.
Paul Lamar
The ignition is looking better by the day. My (maybe) application
would
require a max rpm of around 5600, so that certainly looks feasable. It
will be interesting to see how the 12 Vto 300 V supply works out.
Gary Knutson
They shipped yesterday. I should get it on Monday.
It will be easy to hook up. Only takes a few seconds.
Paul Lamar
-------------------------------------------
The evaluation board 12 volt in High Voltage power supply is
in complete with lawyer shields :)
Little Plexiglas pieces to keep ones fingers away from
the 500 volts.
Paul Lamar
That's a nice looking piece! I realize this isn't your only project but
/home/paul/Desktop/2people-9-24-2013/AA-Mike-Wills-RV4/best-engine-shots/DSCN0089
(Small).JPG.jpg
I'm looking forward to the next test. I would guess it won't really
change anything.
Sometime I would like to get your thoughts on a eight cylinder, twin
plug
system as to what should be duplicated for redundancy. Cost won't
be the
biggest factor.
Is the TC engine getting close to running?
Gary Knutson
I'll know in a few hours. I am getting ready to test it. The biggest
part is the 400 uF
high voltage cap.
I just bought 5 quarts of Mobil 1 for the TC engine. I am thinking I
need to put some
auto transmission fluid in it to free up the apex seals. It probably
hasn't run in 20
years but it has some compression. I'll run it soon. The oil pressure
gage
was a hang up. I don't want to run it with out some assurance it
actually has oil pressure :)
You only need twin plugs if the piston engine bore is greater than 5
inches.
Short stroke big bore is all the rage now a days. You can run it faster
and it breathes better for a given displacement. Formula 1 engines are
like
that. The current wheel driven land speed record engines is like that.
I got to see the current world wheel driven land speed record
car based here in Ventura county. This is slowly becoming
the race car capital of the U.S. Performance folks are moving up
from LA.
Several advances made this possible. A short stroke small block
Dart/Chev V8 that turns 9200 RPM was one. Formula 1 engine tech. The
boost is 40 psi I think but it may be only 40 inches of HG. 386 cubic
inches. Dual large turbo chargers.
There is no cooling heat exchanger because the engine runs at full power
for less than a minute. That means no cooling drag. The engine is
reputed to have 2800 HP running on methanol. There is an ice water inter
cooler with a 20 gallon ice water tank.
This car went 440 MPH and the average of two runs in opposite
directions.
Reached top speed in less than a minute from a standing strat more or
less.
The other advance was a 7 speed pneumatically shifted gear box.
The all billet box cost $22,000. This allowed much better acceleration
in the lower speed range... less than 200 MPH. The turbo engine had a
very
narrow power band so it must be kept on max boost at all times.
BTW The racing world is very small. My next door neighbor's daughter
works for some of
the owners of MacLaren Form 1 team that live in Santa Barbara. Her son
is married to the sister of
Dr. Robin Tuleiu chief scientist for the Mercedes Form 1 racing team. He
is an American
educated in San Diego. You may know him as he used to work for Renault.
Paul Lamar
That's a very sophisticated LSR vehicle! It shows what can be done with
good design, modern materials and electronics, good people and LOTS of
money!
That is a pretty elite group mentioned in the picture. I had heard
of Dr.
Tuleiu but never had the chance to meet him.
The twin plug approach is for dual ignition "comfort" only. I have
always
questioned this method of redundancy as there are numerous other single
points of potential failure. I suppose it stems from the days of less
reliable electric components. If it was up to me, I would only have a
single system. And yes, an engine with a 5" bore is difficult to ignite
with only one plug as is shown by the rpm drop when doing a mag check.
Glad to hear you are getting close with the TC project!
Gary Knutson
Unfortunately the 12 volt HV supply is not working yet. I need to
contact Linear Tech and see if I am doing some wrong.
Paul Lamar
I ran the ignition system with the wall HV supply at a steady 12 ms
period continuously.
That translates to 5000 RPM the fastest my test electric motor would go.
This is the second CD module I have assembled so far. Works the same as
the first.
One more to build for the 3 rotor.
Coil temperatures were barely above room temperatures.
Not surprising as they are being used as a pulse transformers and not
for inductive energy
storage.
IGBT about 200 F. The heat sinks could be a bit taller. I just had those
cut off heat sinks in stock.
CD4049 IGBT driver chip about 200 F. I may bond on a heat sink.
25 watt 1K series resistor about 225 F. No surprise there.
Nothing in the 110 volt 60 cycle AC wall powered HV power supply warm up
at all :)
The plugs spark when moving the magnet by hand past the hall sensor.
That indicates it will start well on a low battery.
Too bad we can't hand prop because of the 3:1 gear box :)
Paul Lamar
Hey Paul,
Put two magnets on that motor driven trigger wheel. Then you can get
10,000 RPM out of it.
Mark LaPierre
Damn why did I not think of that?
Will do.
Paul Lamar
That's why they pay me the big money. ;-) NOT!
Mark LaPierre