David,  check with Tracy on the EM3. The 20B powered
RV8 does use the
electronic throttle. Tracy mentioned he didn't want to
release any
details until he had flown with some hours on the system.
With an
electronic throttle controller, I could build a simple one
in a few
hours, as I have done this before. Building is one thing,
validating and
testing is quite another. Add support and it suddenly
becomes a 500 hour
project. :) For a vehicle it reduces a number of
subcomponents (aux air
valve, cruise control, cable and linkage - NVH reduction,
in additon to
emission or engine saving mode (i.e. built into the
Corvettes to prevent
your 16 you old son from borrowing the car and spinning
high-G donuts
until the engine is starved of oil... hence in that case it
will reduce
throttle slowly as few onramps have more than 360 degree
turns!) Older
systems used an idle control valve. Simple PWM or stepper
motor to
control the amount of air bypassing the throttle plate to
keep a steady
idle. I did make a system to replace the BMW VDO module,
but didn't want
to mess with liability, so it was simplier to repair the
OEM system than
replace it with my own controller. With aircraft and a
throttle control
cable, there isn't much need as we only are at idle a few
times before
and after flight. One thing I recommend is that if the
cable is detached
or slips out of place, is for the throttle go to WOT (Wide
Open Throttle
). Much easier to return to an airport at WOT, and just
kill the engine
once in the pattern. :)  I was looking at a few Rotary
Powered planes
and noticed the stock spring for "return to idle", when I
asked the
pilot about it he commented "never had an issue, so it is
fine that way"

Tom Walter

--

Tracy said effectively the same to me - that was over 15
months ago I
have reached a point where while I would like to use it, it
appears that
it is still not available. I have to do something in the
next few weeks
so I can progress further.

Tracy's - Has something changed recently?

Hey Tom, I'll take the Circuit you mentioned I'll deal with
the support
as it is a one off anyway :) Otherwise,

I guess I'm at cable conversion.

WOT on a Gyro would be very BAD, rather somewhere around
cruise would
be the better choice.

Regards David

--

David, another thing to keep me awake a night... planning
the perfect
electronic throttle controller, with every detail thought
of. Once
soundly asleep I'll wake up with "Gyro, gyro.... I never
even thought of
it being mounted on a gyro" For aircraft is does bring up
an interesting
thought...if you are approaching VNE, should the throttle
start closing?
Personally I like the big red knob (other than when it
comes off in my
hand!) to open and close the throttle on the plane.

The Circuit is a simple uC with a PID loop. Part of the
reason I never
took it too far was little things like the weight of a
flywheel, or flex
plate, had to be considered. A simple "resistor" was a neat
way of
programming the "weighted value" of such, but the more I
messed with it
the more I became convinced of the nightmare. On my
production vehicles,
if you leave the idle switch closed, the engine will sense
high rpms and
realize something is wrong... shutting off fuel control. So
for a
electronic throttle to be fairly fool proof, it needs
should be part of
a larger system.

Irony is the BMW write up (from 1992) about my neighbors
BMW with the
crazy idle is still on the 'net.
http://www.unofficialbmw.com/repair_faqs/idle.html


Tom


Most airplanes have a Red Mixture nob, a Blue Prop Control,
and a Black
Throttle..  :)

Matt-

Right after I posted that.... doh! :)

Tom

--
Hmm, I have the mixture leaning available thanks to Tracy's
EC3 design
but a prop control I don't have because of the slow flight
envelope of
the Gyro and the ability to fly behind the "power curve"
for want of a
better way of putting it the need to have a pitch control
is a "nice to
have" but not required.

My original concept was change the "cable" for wires beyond
that there
was nothing more expected obviously when the throttle
lever/handle/slider is moved then the throttle needs to
follow that but
beyond that there was/is nothing more expected.

Since the Mazda throttle body has a some mechanical
adjustments "screws"
I hoped to set an RPM mechanically for a failure mode based
on that
adjustment and an idle setting based on the idle set screw
inside. Since
they exist that part is not hard.

I have been talking to T.K.(Friend) He has been busy doing
a bit of
research on the Throttle...new information the TPS is
actually a voltage
differential device, it needs a 5V input and using its
output it provides
a "differential voltage" from which you can derive the
throttle position.
He tells me based on this we should have a test
circuit/system in the
next week or so. "TK" tells me he already has "CODE" to
drive it, he
used to in R&D in the auto industry up until not long
ago, without
saying which but Automotive Company but they did file
chapter 11 in the
US recently. His assistance for this is rather handy, I
also discussed
whether we should simply not bother and convert to cable,
but he said he
would like to try this first as he believes it will work.
What can I say
got tp have a fair go at it, it might just prove to be a
nice option,
well it can't hurt to try anyway. :)


Regards David



     David,

An example of the throttle postion circuit (TPS) appears on one of my old Application Notes.

http://www.not2fast.com/electronics/component_docs/AN1791.pdf

The the 68F375 was never released, but the QADC module was used
with quite a few Motorola (Freescale) devices.  The TPS and Temp
Sensor were off my '95 Ford Areostar.

Tom