Hello all,
I just purchased my first jkson listeroid 6/1 from ozlisteroids, it won't be getting here until sometime in January but I thought I would start working on some things before it arrives....
I am thinking about using a servo to control the fuel rack however I also want a fail safe option to shutdown the engine if crap hits the fan or the servo fails for whatever reason. I see two main options, removing decompression and removing oxygen. I am thinking about putting a flap on the intake which is held open by a solenoid which will close and starve the engine when turned off, however I do not know the consequences of doing such a thing, would it suck oil up into the chamber past the rings if there was too much vacuum?
What do you guys think of this idea? I know Bob B has installed a CO2 system for emergency shutdown however this is a bit too elaborate for me to take on at the moment!
Thanks!
Murray
Large ball valve on inlet port? Shutting down inlet air is how Detroit Diesels manage emergency shutdown. Too high vacuum is only momentary and should not affect anything adversely. I doubt that a runaway would be likely with a 6/1 but possible if you had a major malfunction or excessive wear on rings coupled with excessive crankcase splash. There are some threads posted dealing with options to handle such an instance. Decompressing will halt the engine but it could be at the expense of your exhaust valve.
dieselgman
I also dont have a 'roid in hand yet, but I've given emergency shutdown for an overspeed condition a bit of thought; what I've come up with is a (properly counterbalanced) spring loaded weight on the flywheel that would hit a lever and trip a mechanical intake valve closure.
I'd much prefer a purely mechanical emergency shutdown in case of a catastrophic event like a lightning strike that would take out electrical components.
There's a HUGE amount of energy stored in the flywheels.
Just thinking out loud here, but a CO2 fire extinguisher might be a real economical way to to.
Dieselgman as long as I am not going to damage anything by the vacuum pressures, I guess the main combustion chamber is well suited to compression so I guess vacuum can't be too bad for it. large ball valve would be nice, I think I will make an inlet which then goes to a sealed air filter and when I need to shutdown just close off the inlet with a simple flap mechanism, which is probably easier than trying to hook up a spring close ball valve etc.
Simtech I also want something that is relatively segregated from an electrical control system, I am hooking the solenoid up in a fail safe system where the solenoid must be energised in order to hold the intake flap open, as soon as power turns off the flap will fall down and close off the intake ( it could be spring closed as well ) from the electrical side I might even design a system which requires a continual heartbeat pulseon the output of the microcontroller in order to keep the solenoid activated, that way if there is a hardware failure and the pulse stops then the intake will close.
The problem is I would need to flood the area with Co2 and have it in a contained environment, It would be good if I was working with gas or something or as part of a fire system but to shut down the engine itself I have a couple of more simple options which don't require a enclosed environment for emergency shutdown.
The controller will monitor the speed and temperature of the fuel and coolant as well as oil pressure, and if they get out of hand then the fuel rack will close, if the engine doesn't stop then it will trigger the intake flap to close.
I fitted my Roid with an intake valve as noted earlier by dieselgman.
A solenoid might be better, or perhaps a cable/rod attached to the valve lever so the user does not have to reach across the centrifugal plane of the flywheels in an overspeed situation. :o
veggie
ahh that looks great, and the ball valve is a lot smaller than I thought it would be.... The only reason I was thinking about using a solenoid is because as soon as voltage is lost on the small solenoid the flap will close automatically, I guess the same could be done with a valve by having a closing spring that will close the valve in the event that the solenoid turns off, I'm just worried about how much force would be required to open and close the ball valve, whereas a flap (like they have on truck exhausts to prevent the water coming in on a vertical exhaust stack) requires bugger all resistance to open or close...
That valve does look nice and neat though, probably a lot nicer than a flap would look.
Hey guys...
how about a cable actuate disc brake mounted on the crank extention?
Like the ones used on the heavy downhill racing bicycles.
It would probably overcome the 6 hp made by a 6/1 roid.
The user could be off to the side when actuating it.
Veggie
Now thats a good way to stop a run away engine.... when it goes into overspeed just hit the brakes!
Goofy as it may sound - I like it! :o
dieselgman
Quote from: veggie on December 27, 2011, 10:05:01 PM
how about a cable actuate disc brake mounted on the crank extention?
It would have to be a very heavy duty brake assembly to handle the torque, and Also very complex - it is easiest to just shut off intake air. Like dieselGman says, look at the flapper in Detroit Diesels. Gravity operated, very simple, HIGHLY effective. No need to reinvent the wheel.
just need a solenoid with a decent stroke and cheap... ive only seen little tiny ones around, they use long stroke solenoids on some engines dont they?
Woodward makes a full line in 12vdc and 24vdc with either (or both) push and pull functionality and long strokes.
dieselgman
Quote from: carbon-rod on January 04, 2012, 04:38:45 AM
just need a solenoid with a decent stroke and cheap... ive only seen little tiny ones around, they use long stroke solenoids on some engines dont they?
The stroke can easily be adjusted with a lever arm linkage. To match what ever your needs are.
Lloyd
Excellent thanks dieselgman.. I found some on Ebay I will chase up...
Lloyd, the ones that I was looking at were too small even to connect through leverage... plus I want to have a spring on the flap to assist it in closing, it should work pretty good :) when I get it all setup I will post up some pics, it will be a while though as I will only receive my engine this month sometime.
I see much ado about nothing, has anybody ever heard of a runaway Lister CS or listeroid?
The issue is more around my automation of the engine. If for example the servo that controls the rack fails or opens fully or something crazy or the rack itself jamms because of the WVO build up or for whatever reason there needs to be a secondary (reliable) form of shutting down the engine.
It can and will run away...believe me :o
Mine did about a year ago. The rack got sticky from the wvo and the govenor was unable to close it.
Sorry, but I have this mental picture of a runaway Lister hopping away across the fields, flywheels thrashing madly,
belching black smoke........... ::)
Ron
Quote from: vdubnut62 on January 05, 2012, 06:04:32 AM
Sorry, but I have this mental picture of a runaway Lister hopping away across the fields, flywheels thrashing madly,
belching black smoke........... ::)
Ron
B&W or color? Is this about a rebellious adolescent Lister running away from home? ;) Must be a Listeroid since Dursley Listers have impeccable grooming.
Well if you're going to do a spring loaded flap. Just hold it open with a small pin and use the solenoid to pull the pin in an emergency. This would also allow manual engagement in an emergency. I know I managed to stick the hand crank on the shaft while trying to remove it. It was a bit nerve wracking having to reach past it flip the fuel lever, while it was barely hanging onto the crankshaft and spinning at 650 rpm. The rack on mine also got sticky from WVO and was over speeding when a large load was dropped.
vdubnut was the Lister trying to make it to the next state where it could run free with the other listers?
The system would need to be directly connected to the spring loaded flap with the solenoid running continuously in order to open the flap. Basically it needs to be fail safe so that if the control circuit craps itself it will just shut down automatically and not require 12v to be injected by a control circuit, also if the power cable broke to the solenoid while it wasn't activated when you went to try and activate it for an emergency shutdown it wouldn't work.
You could easily automate a roid with a morningstar RD1 relay driver, they are more like a logic controller, it includes timers and voltage and temperature activated features.
Ok I see you want to be really really fail safe, not just an over speed shut down. As the Fab said, you'll need something with a timed delay to hold the flap open while the engine comes up to speed.
yep this is the emergency shut down only, normal shut down and operating will be done by the rack, but if for some reason the engine speed or temperature goes out of bounds then it will shut it down using the flap.
I am building my own controller that will control the rack servo, monitor temperatures and also control the solenoid so in there I will be able to configure all the timings required for start up etc...
OK, so if the thing is running away, it needs to pull the rack wide open, you could put together a Y branch in your intake big enough to hold a ball that will plug the intake pipe, put a small spring loaded detent in the Y branch, when the rack pulls wide open a cable could pull the detent down and the ball would fall into the intake pipe.
No solenoids, no fancy electronics, all controlled by the existing linkages.
mmm this wouldn't work though if the rack was stuck?
I am all for simple, however I am kind of defeating the purpose by building a control system and adding electronics for it any way, but that's ok for my purpose as it doesn't need to be sitting in a field where it is required to be very reliable, for me I would rather a system that is fully automated, and because I have an electrical background that is actually half the fun :) automating thing is what I like to do..
Fab, that's only 1 scenario, agreed probably the most likely, but they can run away by sucking the engine oil past the rings too.
I'm hoping by introducing suction by closing off the intake it won't cause oil to suck up past the rings but I thought in the worst case scenario when I did have to shut it down with the flap at least it won't be able to suck in any air to combust the oil that it pulls past the rings so hopefully it should die pretty quickly...
Ill be checking the rack regularly and making sure its nice and free so hopefully there will never be a day where I need to use the flap, but I reckon it will be very handy if I do ever need it! I might also hook up an emergency stop button on my shed which is in series with the solenoid so I can shut it down manually while keeping my distance :)
Quote from: Tom on January 05, 2012, 05:59:34 PM
Fab, that's only 1 scenario, agreed probably the most likely, but they can run away by sucking the engine oil past the rings too.
They still need air for combustion.
Set it up like a detroit 2 stroke with an air shutdown valve.
It's the easiest surefire way to kill a runaway diesel engine. Programmable engine controller could be used to operate air shutdown on overspeed, or overheat, or fail of rpm to cease on fuel shutdown. Back when 2 stroke detroits were still in highway trucks this was mandatory! They had to have both fuel and air shutdowns.
I know many knowledgeable folks are married to cutting off intake air, but I think if you're automating, that adding decompression control is a better use of your time and effort, since you can then use it for automatic/remote starting, too. This was the approach taken by Lister for the SOM, so I'm not all alone in thinking this is a good way to go.
My 6/1 has a pneumatic rack closer and exhaust valve lifter; they are operated off of the same air solenoid, much like to the SOM. Both could be done with RC servos (giant scale) for those with electric controls. I've seen a tiny commercial servo control board that turns and RC servo into an on/off solenoid.
BruceM
Metro 6/1- for AC power and air compressor
Off grid east of Concho AZ, at 5600 feet elevation
Hey Bruce
Do you have a pic of your setup? I would actually like to look into decompression automation as well, for the exact reason of being able to start with a smaller starter motor, either that or just put an oversized starter on there... I think I might eventually have to use a proxy to pick up spokes for secondary speed control rather than just relying on AC frequency capturing
Bruce, decompressor control for remote starting is fine and indeed what the SOM controls are about... however using that for shutdown could become an issue for possible valve collision with piston crown - especially after carbon has had the chance to build up on the piston (thereby reducing clearances). Lister did not recommend using the decompressor for shutdown. None the less, this could be done (especially for an emergency control) - but with very careful adjustment and measurement to ensure ample clearances are always maintained.
dieselgman
I found some old photos of the exhaust valve lifter.
Since you mentioned it, I included a picture of the Cherry gear tooth sensor I use for speed monitoring, with it mounted next to the flywheel spokes.
I used pneumatics for my Listeroid controls since it is also my air compressor, and I have a Gast 4am based starter with a McMaster rubber friction wheel (another air cylinder presses it against the flywheel).
Dieselgman is right to point out the importance that your valve clearance is sufficient. Since the
SOM valve lifter was likewise directly connected to the rack closer, using decompression during shut down was in fact not an operational problem for the SOM, and that has been my experience as well (about 2000 hrs). I could easily separate the rack and valve lifter by adding another solenoid valve, and I might do that just to save wear on the lifter, someday.
I was careful to check my valve clearance- and set up my lifter so that it does not lift the valve quite as far as the manual "valve holder". I have sufficient clearance to allow for carbon buildup.
It's my experience that the pushrods of the Listeroids are soft enough to flex if you do something foolish on assembly after decarboning and don't have valve clearance.
ahh nice.... did you get the starter idea from bendy2000(youtube)? He runs a similar setup...
that's certainly nice and simple, I have never looked into pneumatics but they seem like a great idea for mechanical actuation, possibly cheaper than electrical and hydraulic?
Quote from: carbon-rod on January 05, 2012, 05:37:17 PM
mmm this wouldn't work though if the rack was stuck?
I am all for simple, however I am kind of defeating the purpose by building a control system and adding electronics for it any way, but that's ok for my purpose as it doesn't need to be sitting in a field where it is required to be very reliable, for me I would rather a system that is fully automated, and because I have an electrical background that is actually half the fun :) automating thing is what I like to do..
You are over thinking this thing...use energize to run..
Lloyd
Quote from: BruceM on January 05, 2012, 09:59:05 PM
I found some old photos of the exhaust valve lifter.
Since you mentioned it, I included a picture of the Cherry gear tooth sensor I use for speed monitoring, with it mounted next to the flywheel spokes.
I used pneumatics for my Listeroid controls since it is also my air compressor, and I have a Gast 4am based starter with a McMaster rubber friction wheel (another air cylinder presses it against the flywheel).
Dieselgman is right to point out the importance that your valve clearance is sufficient. Since the
SOM valve lifter was likewise directly connected to the rack closer, using decompression during shut down was in fact not an operational problem for the SOM, and that has been my experience as well (about 2000 hrs). I could easily separate the rack and valve lifter by adding another solenoid valve, and I might do that just to save wear on the lifter, someday.
I was careful to check my valve clearance- and set up my lifter so that it does not lift the valve quite as far as the manual "valve holder". I have sufficient clearance to allow for carbon buildup.
It's my experience that the pushrods of the Listeroids are soft enough to flex if you do something foolish on assembly after decarboning and don't have valve clearance.
BruceM,
good to see ya back.
L
Quote from: Lloyd on January 06, 2012, 02:57:21 AM
You are over thinking this thing...use energize to run..
Lloyd
Quote from: carbon-rod on January 05, 2012, 03:56:44 PM
The system would need to be directly connected to the spring loaded flap with the solenoid running continuously in order to open the flap. Basically it needs to be fail safe so that if the control circuit craps itself it will just shut down automatically and not require 12v to be injected by a control circuit, also if the power cable broke to the solenoid while it wasn't activated when you went to try and activate it for an emergency shutdown it wouldn't work.
The idea of a rubber roller friction drive starter was something I got from Utterpower, and George B. would be the first to tell you that there is nothing new about that.
I used the Gast motor instead of an auto electric starter motor for drive as I already had an air powered woodshop and some motors left over. This was about 7 years ago, and I did actively publicize the use of the Gast 4am/2am as a simple starter with McMaster rubber friction drive on the Listeroid forums of the time. I was pleased that others also found this easy to make and effective. They used a variety of homebrew drive rollers and enhanced it by using a single air supply solenoid, with small regulator to adjust the engagement force of the actuator. I didn't expect that an air starter would be popular, as I thought I was one of the few with a ready air supply.
Air cylinder actuators are cheap and very powerful, and can be easily and cheaply plumbed with 1/4" OD drip tubing and fittings . The only downsides I've found with air controls are:
1. Things like regulators and check valves, and the decompression valves on my compressor head all do leak slowly to some extent. (I switched to a motorized ball valve to shut off air when the Listeroid is not in use, and use a manual ball valve to close off my reserve air tank. My main air storage tank is 500 gallons.
2. Operationally you must be vigilant regarding keeping condensation water out of the air motors as the cast iron body will corrode, and the motor will start binding. The Listeroid's need for manual lubing every 8 hours of run time is fortunately compatible with with the need for bleeding off water from the air system, when lots of air compressing is done. I only have to be vigilant during our monsoon season.
Bruce, good to see you back. Hope all is going well.
FWIW, you were my inspiration for the control system for my 6/1 that I'm slowlly implementing at my wife's place in Washington. Especially as regards the decompressor and fuel rack, which are both controlled by pneumatic cylinders retracting against spring pressure when air pressure is present. Any fault in the air system, or if something goes wrong will automaticallyl close the fuel rack and actuate the decompressor cam by spring pressure. Can't get very much more KISS than to rely on a spring to shut off compression in a diesel.
I'm using a Toyota Camry starter turning a 2.5" rubber roller (Mcmaster) to drive the flywheel, held in place by a 2" air cylinder with spring retract. Two air solenoids and 3 air cylinders will control the whole system.
Air cylinders are cheap and reliable and simple to implement. Has KISS written all over it. www.surpluscenter.com (http://www.surpluscenter.com) is a great source for cheap air cylinders. McMaster.com has them too http://www.mcmaster.com/#standard-air-cylinders/=foutwv (http://www.mcmaster.com/#standard-air-cylinders/=foutwv), and the hardware (clevises, pushrod ends, etc.) you might need to mount them. It's a natural with air starting like Bruce has done, but even though I'm using an electric starter on my 6/1 I'm actuating the starter and the shutdown paraphernalia via air because it's cheap and easy and fail-safe.
Quinn
Quote from: carbon-rod on January 06, 2012, 06:44:30 AM
Quote from: Lloyd on January 06, 2012, 02:57:21 AM
You are over thinking this thing...use energize to run..
Lloyd
Quote from: carbon-rod on January 05, 2012, 03:56:44 PM
The system would need to be directly connected to the spring loaded flap with the solenoid running continuously in order to open the flap. Basically it needs to be fail safe so that if the control circuit craps itself it will just shut down automatically and not require 12v to be injected by a control circuit, also if the power cable broke to the solenoid while it wasn't activated when you went to try and activate it for an emergency shutdown it wouldn't work.
On an energize to run system, everything has to be working else the system won't start. So it goes like this, the fuel rack solenoid only opens when in the run position, now the over temp, and low oil are also wired in this system, along with over/under speed, then so is the butterfly valve on the intake(you can get one of these from Granger) the butterfly valve can run on the same linkage to the run solenoid for the fuel rack.
So a fault at any system monitor ie over/under speed, low oil, high temp, de-energizes the run-solenoid, which then closes the fuel rack, and the intake butterfly valve, if you want belt and suspenders I would use a separate solenoid for the butterfly valve. I would also put a temp sensor on the exhaust.
Lloyd
Quote from: Lloyd on January 06, 2012, 02:24:20 PM
Quote from: carbon-rod on January 06, 2012, 06:44:30 AM
Quote from: Lloyd on January 06, 2012, 02:57:21 AM
You are over thinking this thing...use energize to run..
Lloyd
Quote from: carbon-rod on January 05, 2012, 03:56:44 PM
The system would need to be directly connected to the spring loaded flap with the solenoid running continuously in order to open the flap. Basically it needs to be fail safe so that if the control circuit craps itself it will just shut down automatically and not require 12v to be injected by a control circuit, also if the power cable broke to the solenoid while it wasn't activated when you went to try and activate it for an emergency shutdown it wouldn't work.
On an energize to run system, everything has to be working else the system won't start. So it goes like this, the fuel rack solenoid only opens when in the run position, now the over temp, and low oil are also wired in this system, along with over/under speed, then so is the butterfly valve on the intake(you can get one of these from Granger) the butterfly valve can run on the same linkage to the run solenoid for the fuel rack.
So a fault at any system monitor ie over/under speed, low oil, high temp, de-energizes the run-solenoid, which then closes the fuel rack, and the intake butterfly valve, if you want belt and suspenders I would use a separate solenoid for the butterfly valve. I would also put a temp sensor on the exhaust.
Lloyd
If you want a nice belt buckle for those suspenders Lloyd one could add an optical opacity gauge (LED optocoupler + some simple comparator electronics) to shut down if too much grey/black smoke in the exhaust has crossed a nastiness threshold.
I like the sound of your system, Quinn. By using an electric starter, you now need very little air, your plumbing, regulator and air solenoids can be the smallest and cheapest ones, and your air budget is essentially only for leaks. I think your failsafe scheme is excellent.
The safety/failsafe issue is a good one to ponder for a while. My highest design priority was to maintain "manual reversion"; the ability to operate the Listeroid completely manually with no power, no battery, no AVR (harmonic only), with no special operations to do so. This was in part because with so much of my own, new, prototype hardware and software, I wanted the piece of mind of knowing that I could at immediately operate manually "no matter what". I needed the Listeroid power for compressed air daily during 3 years of construction (even my skill saw is air) and could not go without. I also had the unusual need to run my engine with just the air compressor, no AC at all, since I can't be near the spinning generator head for more than 30 seconds without it affecting my epilepsy.
After that, I decided that since I had no wife or kids involved, that I would just opt. for the simplest (for me) solutions. If anything fails on my system, the engine just keeps running; there is no watchdog timer on the processor or any other failsafes. The controller does monitor for low air pressure, and will shut down for that, low oil, vibration, high temperature, no load timeout (great for people like me with memory problems) and under/overspeed. If air pressure is suddenly lost (all 500 gallons of it?!), then I'm just back to the manual operation that most guys have. Likewise with the loss of the controller or it's 12V (PV charged) power. I can switch it off or on at any time- if the engine is running when the processor wakes up, it takes control but leaves it running. Likewise, if the remote control panel in my distant shop is switched off or loses power, the Lister controller assumes "carry on as previously directed and monitor". In the last 5 years, I've never had a glitch or processor failure of any kind, so I really like the PIC/Picaxe chips.
After the experience I have now, I would now consider more fail safes, but the reliability of the controller and pneumatic controls has been so good that I'm not in a hurry, and other projects have priority.
Quote from: Lloyd on January 06, 2012, 02:24:20 PM
Quote from: carbon-rod on January 06, 2012, 06:44:30 AM
Quote from: Lloyd on January 06, 2012, 02:57:21 AM
You are over thinking this thing...use energize to run..
Lloyd
Quote from: carbon-rod on January 05, 2012, 03:56:44 PM
The system would need to be directly connected to the spring loaded flap with the solenoid running continuously in order to open the flap. Basically it needs to be fail safe so that if the control circuit craps itself it will just shut down automatically and not require 12v to be injected by a control circuit, also if the power cable broke to the solenoid while it wasn't activated when you went to try and activate it for an emergency shutdown it wouldn't work.
On an energize to run system, everything has to be working else the system won't start. So it goes like this, the fuel rack solenoid only opens when in the run position, now the over temp, and low oil are also wired in this system, along with over/under speed, then so is the butterfly valve on the intake(you can get one of these from Granger) the butterfly valve can run on the same linkage to the run solenoid for the fuel rack.
So a fault at any system monitor ie over/under speed, low oil, high temp, de-energizes the run-solenoid, which then closes the fuel rack, and the intake butterfly valve, if you want belt and suspenders I would use a separate solenoid for the butterfly valve. I would also put a temp sensor on the exhaust.
Lloyd
That is almost exactly what I am planning.... I think it was mentioned on one of the previous pages.
The only difference is there will only be one solenoid to shut the intake flap / butterfly valve (good idea, I might use a butterfly instead of a flap) the rack will be driven by an RC servo so that will already be controlled electrically, if for some reason the servo is unable to control the rack ie rack is binding or servo fails then the secondary form of protection will shut the engine down.
Bruce that does sound like a great setup you have there, unfortunately for me I won't have an air supply to use for starting / actuators so I might end up having to use an electrical method instead to initiate starts. It is unfortunate because a linear actuator wouldn't come close to the same functionality of an air cylinder to push the wheel against the flywheel.
I will be using an Atmega32 processor most likely, plenty of IO for sensors etc..
Bruce,
The failsafe aspect was what hooked me on using air. I have a nailgun compressor that's tighter than a frog's . . . uh, meaning it doesn't leak appreciably over the month intervals that I'm away from the wife's place, so I figured I'd put it to work when I'm not nailing nails or blowing pine needles and/or sawdust out of the groj. Will likely set it up on a dedicated circuit and have it turn on once/day in case it starts to leak and I'm not there.
And I've recently gotten an Arduino board and have been experimenting with turning on and off LEDs and transistors. Lots of apps out there, and so long as it can turn on and off relays, it will serve my needs. So I think that's the way I'll go for a control system when I get there.
Like you, I wanted to keep things simple and maintain manual capabilities at all costs. But when it's below freezing the 'roid takes some cranking to get it to light, so I didn't want to chance running out of air. Also invested in a Jetta glow plug and drilled the dummy plug. I'll eventually get around to doing the automatic shutdown controls, etc. But for now I want the wife to be able to walk outside 50' to the groj which will be illuminated by a 4W LED emergency light run off the starting battery, turn on a power switch which will energize the 12V bus and enable the air solenoids, then hit the glow plug switch, start switch, RUN switch, then let go of everything when the music starts. And when voltage appears on the control board, a relay will connect to the line going to the manual transfer switch INSIDE the house and she can turn whatever circuits she wants. If she forgets to shut off the genny prior to killing the engine I'll have that covered, too. Thee aren't any large appliances, so I think that should cover it. Mainly want to have the gas heater blower (1/4 HP) 'fridge and lighting work.
Quinn
Quinn,
How do you find the Arduino so far? they are extremely popular these days for people just getting into electronics, I think the PIcaxe that Bruce uses is pretty much a similar concept from a different manufacturer.
The arduino is plenty capable of running relays etc and once you get into the hang of it the world is your oyster... You will find yourself getting excited and automating a lot of stuff then! your mrs will end up sitting inside the house and just pushing a single button in no time :)
The Arduino is really neat. I had been thinking of putting something together using discrete components, but when I read a little about the Arduino, I realized the microprocessor can do an awful lot of things that you just can't do with transistors, resistors and caps, which is the limit of my rudimentary knowledge of electronics. And there are so many geeky people out there doing stuff with them, it's pretty easy to find plans and sketches (programs) for things like thermostats, motor controllers, tachometers, and the software has decision-making capabilities, if-then, if-then-else, etc. And a board is only about $25 and everything is open-source. So I'm pretty happy with what I've seen so far. I don't want to buy a controller, in fact I don't want one if I can't do it myself. That's the thrill/joy/buzz I get from doing stuff like this.
Just Google whatever app you're interested. For instance "arduino tachometer" gets you pages of applications and YouTube videos showing how folks have done it: example: http://www.youtube.com/watch?v=rmCNe7kJAe4 (http://www.youtube.com/watch?v=rmCNe7kJAe4)
I agree the amount of electronics required to be able to come close to a microcontroller is just crazy, they are so versatile and if you want to add new functionality its so easy to do without having to re-wire everything...
I'm going to attempt to determine the speed of my engine (when I get it) by looking at the AC output from the alternator. I will step it down using a small transformer so it's in a workable voltage range, and then use a fairly simple circuit which will send a digital pulse into the microcontroller which I can monitor and vary the output speed from there...
I also wouldn't want a controller on the engine that I couldn't build myself.. It's just so much more fun and also you can design it and make it exactly how you want rather than having to put up with the shortfalls of a purchased controller..
Quinn- I found some air pressure sensing switches at Grainger which could automatically start your lovely compressor only when needed. I would have liked an analog pressure sensor, but they were hundreds of dollars.
I agree the Arduino's are a bargain, very capable, and the support base is growing. A very good choice for a hobbyist project. Of course I'm still very fond of the Picaxe chips, since I "cut my teeth" on Basic in the mid 70's. (It's the same as Stamp Basic, with some extras.)
I have a project I'm working now that I may use a Teensy AVR board for, using it's USB interface. It's a "fly off" between that and a PIC USB development board- to see who's software is easier to cope with for me.