This is a CD4049 inverter running on a 5 volt supply.
The lower trace is the signal out of the upper 2nd gen CAS at a 50
ms period. That tranlates to 1200 RPM.
One side of the CAS is grounded to the 5 volt supply.
It still works at 100 ms or 600 RPM. It is just ticking over:)
A couple of bias resisters will allow it to work much lower than
that. The scope has a hard time working that slow. I need my other
digital scope to go that slow :)
This is only one of the 6 buffers in this chip.
Paul Lamar
This circuit works down to 400 RPM and lower. How much lower I can't
test at the moment. The 24 volt electric motor is running on only 3
volts.
Paul Lamar
That's great. This means that the ignition system will not only
work when the engine is running but also when the operator tries to
start it up. No super duty starter or huge battery is required to
spin this thing up over 600 RPM just to get the sparks working.
Mark LaPierre
Here is a chip that will work with fraction of a volt from the CAS.
It is called an LM311 comparator. Been around for 50 years. There
are some new CMOS versions that work even better. In this movie you
can watch the 2nd gen CAS rotate on less than a volt.
The CAS is also putting out less than a volt peak to peak and we are
still getting a usable trigger pulse. Good for hand proping :)
BTW I think what Kevin is talking about is making a leather pocket
that will fit the tip of a prop with a rope attached. Set the prop at
10 AM or so. Use the rope to jerk the prop 90 degrees. Due to the 3:1
gear box that will rotate the engine 240 degrees which should be
enough to start it. If the prop is clocked correctly each rotor
should fire once.
Paul Lamar
http://www.ti.com/lit/ds/symlink/lm1815.pdf
http://www.ti.com/lit/ds/symlink/lm1815.pdf
http://datasheets.maximintegrated.com/en/ds/MAX9924-MAX9927.pdf
Chris Smale
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