That's easier, because they can connect to the engine wiring. The ones I've worked on got a message from the speed regulator, or just held the start button for a fixed interval then checked to see if the generator was coming on-line.
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Tim Wescott
Wescott Design Services
http://www.wescottdesign.com
Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" gives you just what it says.
See details at http://www.wescottdesign.com/actfes/actfes.html
I fully understand and agree with your concerns. Besides, altering any circuits of the car can void the warranty and opens you to the liability claims.
[...]
Yes. You can even measure the engine RPM by the pulsation of the onboard power.
It is better to lowpass it in order to pick the pulsation made by the car alternator.
True. On some vehicles, it does not work.
Is it the only sense available or can you use anything else? If there is only the power connection, I would use an MCU to detect the voltage and pulsation, and then do some logic with it. Probably will fit into 0.1mA consumption in standby mode.
It depends on how much is the great appreciation.
Vladimir Vassilevsky DSP and Mixed Signal Design Consultant
Bad idea? Hmmm, I wonder how the high powered car amplifier market gets by. They sell millions of those things a year. Perhaps because they do not actually supply the wiring? Similar case to the electric hedge cutters. Ever see one lately with a corded pigtail for power? No? That's becuase some fool probably cut through the supplied pigtail, sued them, and won. So, to counteract, the guys making the hedge cutters molded a plug into their handle. Now if the fool cuts through the cord, they need to sue the extension cord maker :).
I'll let our lawyers determine if we supply wiring, fuses harness to connect to VBAT, etc... Or if we play it on the safe side and make it the customers responsibility to supply these goods.
I design underhood electronics to survive all know electrical system faults and SAE-J1113-11 transients at +125C
Product design and packaging will take this into account.
I didn't want to run additional wiring. However, if I have to, IGN would be my 1st choice.
My marketing department is fighting tooth and nail with me to simplify the installation of this sucker as much as possible. The obvious answer would be to add an ignition feed similar to what we do with a similar OEM product. However, their marketing studies have shown this may scare off potential buyers, or, increase installation complexity.
The whole thing about installation complexity is not so much for the person with a little bit of ambition who may know what they are doing. It is more for the person who does not have a clue to what they are doing and would have a mechanic install the product. Marketing feels adding an ignition wire (or any other external sensor) would add too much time to the installation. Time is money when paying a mechanic. The mechanic may charge more than what the consumer paid for the product... Therefore, I have been given the challenge to keep this self contained (and as cheap as possible of course).
If my product were rigidly mounted somehwere in the engine compartment, say on the fire wall or the inner fender, do you think it would be acceptable to house a piezo electric element inside my product? Wouldn't vibration from the road or engine also vibrate my module which is coupled to it?
Can anyone think of an instance where the vehicle would NOT be running or moving but some external source of vibration would allow my product to activate? I'm thinking EARTH QUAKES for instance :). Seriously though. The module would only be active while vibration is sensed. It would de-activate when the source of vibration goes away. Would it matter if my product activated itself for 3 minutes while an earth quake took place and then shut off immediately afterwards? That's
250mA/hr off the batteries charge. I've never been present during an earth quake so don't know if this is the case.
Then there is ferry transport, rail transport, tow trucks, etc... This one is not trivial is it?
One last question. Say I wanted to look into Piezo Electric elements. Where might one start to find something that is automotive grade?
I thought about the piezo mounted inside your unit the instant I hit the send button to post my last message. :-) Yep, I think it would work.
You'd have to filter the piezo's output to only respond to the band of frequencies that would represent the engine running. You'd need to do some real-world testing to establish frequencies and amplitudes. You'd also have to add timing to guard against transient vibrations and anti-resonances that might temporarily reduce the vibration levels below your threshold.
If your product incorporates a micro, handling the piezo shouldn't be difficult to do, and shouldn't require much program memory or processor resources. And if you're not using a micro, why not? This is the 21st century. Get with the program! :-)
For your initial test and evaluation, I'd recommend that you obtain several different types of small encased piezo sounders. Then seal the sound holes. Give them an environmental test to see which stand up to your conditions. (I'll bet that they all will. Unless you overdrive them, they're rugged little beasts.) Or Google for vibration sensors, vibration transducers, etc. Probably others in here with more experience applying piezos will be happy to provide you with better advice.
Odd you mentioned towing. I didn't think of that. My thought was to filter against wind, parking lot bumps, etc. Having lived in California, I even thought of earthquakes, but I wouldn't put earthquake survivability into your design requirement document. In any case, proper filtering should guard against just about any external source of vibration.
I wish you luck with your product. I hope it's a big win for you folks.
I thought about the cigarette lighter circuit, too. Then I thought about all the plastic I'd have to remove in my own car to get anywhere near the cigarette lighter wiring. In many cars, that would be a major undertaking.
Well yes. It really depends on who does the install. If it's the clueless bozo that you're apparently you market audience, anything that requires tools is a bad idea. Horror stories on request.
Most are installed by auto electronics shops (and then cleaned up by auto electric shops after the wiring harness gets torched). It can be done successfully by anyone who actually follows the instructions, but your target audience apparently doesn't qualify. You're correct. Directly wired to the battery.
See item #7 on fuse location.
Incidentally, if you want your worst case nightmare for do it thyself automotive electronics, see:
in the "Show off your project" forum section:
Some of the installs are rather marginal bordering on dangerous. Others are really impressive works of electronic artisty. The majority seem to survive without fire or an extended vehicle warranty. I'm shopping for new wheels and plan to install a computer in roughly the same manner.
You're stretching it a bit. Between about 1973 and 1985, my hobby was product liability litigation. It was a hobby rather than a profession because I carefully avoided most pitfalls and traps in the products I helped design. I would collect horror stories from the news and trade journals and bring them to meetings. That would inspire the others to be VERY careful. Anyway, if you have any relevent horror product liability horror stories, please make them relevent to user installed automotive electronics. Hedge cutters aren't even close.
Actually, the lawyers don't decide anything. They advise.
As I understand it (possibly wrong), dumping the responsibility on the customer, where the customer is forced to make a decision based on insufficient information, is a loser in court. The customer merely has to say that he did not understand the instructions and they're off the hook. It's your responsibility to insure that the customer cannot do anything wrong, cannot misinterpret, and cannot injure themselves. Consult and attorney to be sure.
Ok, I have a design question. It draws 5amps. How are you going to turn it on and off or is that the purpose of the engine run detector? If this is the case, how are you going to prevent Joe Sixpack, from placing a boom box on the air filter, and playing race track sound effects CD's at full blast, causing your engine sound activated contrivance to falsely activate? No answer required, but at least think about the many ways in which such a system can fail.
Incidentally, does this have to work in a hybrid? They don't make very much noise when running on battery.
Well, it does have the benifits of simplicity. However, once you have a microprocessor to abuse, engine run detectors can be made as complicated and elaborate as the software will allow. Complex algorithms, that accept input from multiple sensors (sound, vibration, IR, acelleration, etc). We're not fighting for every byte of RAM or counting CPU cycles these days.
Glad to be of assistance. Incidentally, I spent 9.5 years designing consumer marine electronics. It's not the same as automotive, but it's close enough with the added enjoyment of a corrosive environment and a semi-intoxicated operator.
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# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558 jeffl@comix.santa-cruz.ca.us
# http://802.11junk.com jeffl@cruzio.com
# http://www.LearnByDestroying.com AE6KS
Have a design concept for non-contact and low power, could be battery powered. automotive ignition detector uses non contact radiated engine or electric motor contractors spikes, and a coincidence detector. PLease contact me for commercial versions of this module!
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"it\'s the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
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| James E.Thompson, P.E. | mens |
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America: Land of the Free, Because of the Brave
The engine isn't running under those conditions, just the motor(s).
Best regards, Spehro Pefhany
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"it\'s the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
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