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
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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
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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
