12v ignition cut device using ardiuno - Page 1
Forum section: electronics / projects

author: knudsenuk
author_rank: Contributor
timestamp: June 07, 2024, 06:28:19 am
content: Hello all, I am trying to design a way to cut the ignition for a short period based on an input to an arduino. Everything works except for the fact that I can only supply a 5v "on" to the base of the transistor, resulting in the output being 5v too, not the desired 12v. Can anyone suggest a solution. It needs to be fast, so a relay maybe too slow. Any help appreciated

author: moffy
author_rank: Super Contributor
timestamp: June 07, 2024, 08:18:15 am
content: Have an NPN transistor's collector connected to a PMOS transistor, with a couple of resistors, switch the +12V.

author: Phil1977
author_rank: Frequent Contributor
timestamp: June 07, 2024, 03:08:12 pm
content: If you want to switch on the high side, in other words on the +12V you should use a PNP-transistor.I´m not sure if you are aware of the nature of switching highly inductive loads on a vehicle net. A simple transistor without dedicated back-emf protection is more or less dead within miliseconds.

author: langwadt
author_rank: Super Contributor
timestamp: June 07, 2024, 05:05:24 pm
content: https://xyproblem.info/

author: knudsenuk
author_rank: Contributor
timestamp: June 08, 2024, 07:44:56 am
content: I intend using a solid state relay to do the actual switching of the load.

author: Andy Chee
author_rank: Super Contributor
timestamp: June 08, 2024, 08:12:14 am
content: What part number is your proposed solid state relay for actual switching?

author: John B
author_rank: Frequent Contributor
timestamp: June 15, 2024, 12:40:43 am
content: Am I right in thinking you are trying to implement an ignition cut on fast gear changes?If so, many, many more details are needed.The proper way to do any ignition timing alteration is from the source, ie a programmable ECU.

author: knudsenuk
author_rank: Contributor
timestamp: July 25, 2024, 01:06:50 pm
content: Quote from: John B on June 15, 2024, 12:40:43 amSuch as?If I had a programmable ECU I would't need the quick shifter. And it' not an alteration to the ignition timing it simply suspends the ignition for a set time to stop drivetrain stress through the gearboxMy solid state relay controlled by an Arduino worked fine with a pretty simple program. It cuts the positive supply for a prescribed time. I can't think what else is needed.

author: squadchannel
author_rank: Frequent Contributor
timestamp: July 25, 2024, 03:26:42 pm
content: To use an NPN as a high-side driver, the voltage between the emitter and collector plus 0.7 V is required.Generally, to use an NPN transistor on the high side, either drive it with a "high-side driver" or use a PNP transistor.However, transistors are very lossy and are best suited for "analog" purposes, but not for simple switching.Use a P-channel MOSFET. Don't forget resistors at the gate and source.As this is a quickshifter, we assume it will be used in a motorcycle, not a car.The rectifier circuit in a motorcycle generator is very low-cost and has a lot of ripple, making it a power source that can easily cause microcontrollers and other devices to malfunction. Proper noise rejection circuitry and an LPF design for the sensor are needed.You can see why commercially available quick shifters are so expensive.MOD:Frankly, I don't see the need for a quick shifter on a motorcycle.Throttle control allows you to shift up and down with no clutch.Even if you cut the ignition to release traction, that only works when upshifting and you need a way to rev up when downshifting, which is very complicated.This is just my opinion. Don't worry about it.

author: SteveThackery
author_rank: Super Contributor
timestamp: July 25, 2024, 04:39:28 pm
content: Quote from: squadchannel on July 25, 2024, 03:26:42 pmNeither do I, to be honest, but lots of people do, which is why it is available on a wide range of motorcycles. A clutchless change using just the throttle is perfectly possible, but it is WAY slower than a quickshifter can manage.Quote from: squadchannel on July 25, 2024, 03:26:42 pmAbsolutely. That's why quite a lot of quickshifters only work on up-shifts; throttle-blippers for down-shifts imply a full fly-by-wire throttle system, which adds considerably to the cost. No doubt they'll get cheaper and more ubiquitous as time goes by.

author: knudsenuk
author_rank: Contributor
timestamp: July 29, 2024, 07:18:54 am
content: This bike is used on a race track and I can guarantee you will go faster with a quickshifter. On the road, I'm not sure it's really necessary. although my BMW GS1250 has one and it's quite slick when you want to press on but only works well at higher RPM. A blipper could be a stepper motor on the throttle butterflies in theory. The secondary butterfly's are controlled in a similar way on my 2004 ZX10 which has dual throttle cables

author: SteveThackery
author_rank: Super Contributor
timestamp: July 29, 2024, 08:03:09 pm
content: Quote from: knudsenuk on July 29, 2024, 07:18:54 amCouple of things, here. Firstly, your motorcycle will have two throttle cables, one to open the throttle, and the other to close it. When correctly adjusted there should be very little free movement of the throttle plate. That makes it impractical to blip the throttle with a motor because the throttle plate is, effectively, locked in position by the two cables.Secondly, I very much doubt that a blipper would use a stepper motor - a servo motor is generally much faster, and that is what's required. On my bike the blip lasts only a few tens of milliseconds.Another point: the secondary throttle plates are controlled electronically, but they cannot do a blip by themselves because a blip would requireboththrottle plates - the motored secondary and the cable-controlled primary - to open. The secondary throttle plates can onlyreducethe effective throttle opening, not increase it. They are there to moderate the instantaneous response to rapid throttle movements by the rider.*(*) On my Versys the secondary throttle is also used to implement a cold start fast idle. At the very extreme of its travel, a cam on the secondary throttle lifts the primary throttle plate off it's idle stop by a few degrees.

author: joeqsmith
author_rank: Super Contributor
timestamp: July 29, 2024, 08:58:27 pm
content: Quote from: knudsenuk on July 29, 2024, 07:18:54 amA bike, very nice!!There may be a better way that trying to cut the power to the coil. Can you provide more details? Which bike, ignition....

author: joeqsmith
author_rank: Super Contributor
timestamp: July 29, 2024, 09:09:46 pm
content: Quote from: squadchannel on July 25, 2024, 03:26:42 pmOne purpose would be to shift faster. Another would be to improve the consistency. There may be no concern for down shifting, and we may want to keep the throttle open. We cut the ignition just long enough to unload the transmission to perform the shift. The actual mechanical movement is done with pneumatics. Ideal would be to shift under full load which can be done with a custom transmission. All depends on what you are after. A bit off topic.

author: knudsenuk
author_rank: Contributor
timestamp: July 30, 2024, 12:09:28 pm
content: Not on mine. We removed them. But you are right, the throttle cables would restrict an "autonomous" blip. Not sure what motor was on the secondary flaps but I imagine speed is not crucial for them to function as desired so again a very valid point. Anyway in the spirit of caving in, I bought a translogic system, mainly because I don't want to risk a £2k gearbox

author: SteveThackery
author_rank: Super Contributor
timestamp: July 30, 2024, 12:49:20 pm
content: Quote from: knudsenuk on July 30, 2024, 12:09:28 pmThe one on my Versys was a stepper motor. Out of interest, why did you remove the closing cables?

author: squadchannel
author_rank: Frequent Contributor
timestamp: July 30, 2024, 03:21:54 pm
content: I have diverted you from the topic in my message, but there are several ways to do this.The first way is to control the 12V line feeding the ignition coil, as you considering.For controls that use the primitive "CDI" or "TCI" method, it is difficult to control the ignition coil.A transistor with a voltage that can withstand about 500V is required, and it is dangerous. It is very painful.From your question, I don't think it is such a bike.Another is to use a control line used for a "safety features" such as a kickstand, etc. Unless the bike is pre-1990 or a cheap bike, there will always be a control line that stops the ignition with the kickstand as a safety device. Hacking this control line can be achieved without using a large switching device.The problem is that some bikes seem to use this "safety features" as a "reset" for the internal uC.Modern bikes are equipped with actuators in various places to purify exhaust gases and increase power output. After this actuator is reset, it initializes and then performs the actual control.Therefore, switching it while the car is running would cause problems.To begin with, this control line is not designed to be used in such a way; it may have an LPF or similar built in and not be able to detect the few milliseconds of signal needed to shut off the ignition.The second method is limited to the bikes that can do it.If it is a cheap or old bike, it may not use uC, but an analog method, an op-amp or comparator to control the ignition. If so, it is controllable.Anyway, try using and controlling PchFETs as I mentioned before. I think it will work.The sensor can be a simple microswitch, or you can get a commercially available sensor from ebay and install it on your bike.My recommendation is the domino sensor on the Ducati Panigale, but it is expensive.I think it is feasible.My bike, NSR250R, is equipped with something close ECU called "PGM-3".Ignition is controlled by CDI system, but since this bike was produced during the transitional period with direct ignition system, control of ignition timing and exhaust valves is done by uC (NEC uCOM-87AD). Controlling the kickstand on this bike, as mentioned, causes problems.The control of the exhaust valves and ignition timing is initialized once, and after about 500 milliseconds, the control is restored. It is not rideable.

author: joeqsmith
author_rank: Super Contributor
timestamp: July 30, 2024, 08:42:53 pm
content: I would imagine the road race bikes are more difficult to control. For my old race bikes, I am using 1-2 autos. This allows me to ride them without the need of being towed. The ignitions are aftermarket and all support kill. These bike have only one cable and basically the throttle is held open the entire time.My street bike is an old Busa. Their ECMs were hacked and the kill was added to the firmware. Like the race bike, still button up shift. Unlike my race bikes where fuel continues to feed into the motor which makes its way into the exhaust and will make loud bang after the kill is released, my street bike can turn off the fuel as well. The problem is that the stock fuel system can't provide the fuel so a second one is ran in parallel. It's a really bastard ed up setup but fun to ride.

author: langwadt
author_rank: Super Contributor
timestamp: July 30, 2024, 09:37:08 pm
content: Quote from: joeqsmith on July 30, 2024, 08:42:53 pmthe bangs in the exhaust from cutting ignition can be really bad for the engine, causing exhaust valves to jump off the seat, loosing shim, damaging cams etc.cutting fuel also has disadvantages, though not as bad if you individual throttle bodies and no lambda sensors

author: joeqsmith
author_rank: Super Contributor
timestamp: July 30, 2024, 11:47:10 pm
content: Quote from: langwadt on July 30, 2024, 09:37:08 pmFrom my experience, it's not been any problem. If you think the bit of raw fuel igniting in the exhaust is bad, you should hear it on the 2-step. My bikes are all fairly smooth and will make about 7PSIG sitting still. Bike leaves under pressure. The high power guys today are far more violent. Check the following short vids to get some idea what I am referring to. Second video is in the dark.

author: joeqsmith
author_rank: Super Contributor
timestamp: July 31, 2024, 12:41:38 pm
content: Video explaining the 2-step limiter (why and hows). With my race bikes, this is all done in the ignition, which today is programmed with a PC. For my street bike, the ECM handles it.

author: knudsenuk
author_rank: Contributor
timestamp: August 05, 2024, 03:11:15 pm
content: I removed the secondary flaps, not the cable that closes the throttle, that could suicide!