How electronic ignition works and also how to make a spark plug play music | Hacker News Reader

How electronic ignition works and also how to make a spark plug play music

theautopian.com

56 pointspavel_lishin35 comments

That's called a "singing arc".[1] It's a plasma speaker. Those are good tweeters, but run in air, they generate too much ozone.

In helium, though...[2]

[1] https://teslascience.wordpress.com/making-a-music-playing-pl...

[2] https://www.youtube.com/watch?v=aeMCBb_Fo78

Is the sound coming from arc itself or the metal that its touching?

The arc itself. The plasma generates the sound. This is a very low inertia speaker.

Link [2] shows the commercial version of that speaker, with a large helium tank.

Is the generated ozone undesirable because it's dangerous / unhealthy for humans?

P.s. the videos in the first link are wild

https://youtube.com/watch?time_continue=144&v=puch1sLN0mg

Yes.

> ...is any of this useful for anything? A musical ignition coil might not be...

Some Siemens engineers decided that if they couldn't get rid of locomotive startup leaking into the audio bands, they might as well make it sound like they meant to be playing it: https://www.youtube.com/watch?v=DpMxETSV4K8

We used to play music on the coils of BLDC drone motors when learning to control them in university 12+ years ago when that was hot shit.

The Montreal metro also had a pleasant three tone chime on the older MR-73 trains.

Between the Autopian, Defector, 404Media, and about a dozen other sites, it's fascinating how much good writing, interesting content, and genuinely great internet was apparently being held back by whatever combination of VC, private equity, and just general herb-ish "media executives" over the last decade. It didn't _have_ to be the decade of the listicle, we didn't _have_ to lose the entire media ecosystem, there was still an audience for good content.

What is that supposed to mean? Are you complaining about Autopian's refusal to show you the media for the article unless you accept marketing cookies? Because you should be. Here's the article from the guy who did the work: https://newscrewdriver.com/2024/06/08/toyota-sienna-denso-co...

Let me add, (from experience) that any way the plug gets lit, whether it be old school distributor, coil pack, or coil on plug, it can shock a human very badly. It's easy to get lulled into a false sense of comfort working on 12v automotive electricals, but the power levels going to the spark plug are much higher.

I build and sell reproduction electronic ignition units for old 1980s sports cars, and I've gotten hit with the full secondary voltage on my bench setup a couple times. Even with current limiting and safety cut-outs in place on my bench top power supply, it is very, very unpleasant.

Don't those coil packs distribute 10-20k volts?

I'm kinda sad that as far as I can see, no cars have protections against 'stupid DIY mechanic puts finger in spark plug while cranking engine'. I'm sure those sparks have killed many people by now.

All they'd need to do is have the spark happen not to ground but to another return wire, and then check the impedance between both wires and ground is infinite before firing.

Plenty of other benefits to such a design - eg. you can more accurately measure flame propogation within the cylinder (detect bad nozzles on injectors).

> I'm sure those sparks have killed many people by now.

Probably not many. I have been shocked when I was twisting the distributor on my old '95 Tahoe to adjust timing after maintenance. It bit me good but I have felt and survived worse.

Those who don't survive don't post on HN

I never heard of them killing anyone. Though I am sure the resulting shock might be enough to trigger issues in those with weak hearts or injury resulting from pulling away rapidly where a fall or slip can cause a severe injury.

Most of my social circle is people that do custom crazy stuff with things with engines. 1000hp off-road trucks, jetskiis that do backflips, cars into the 9 second quarter mile, basically all installation and repair work done by the enthusiast themselves.

I know several people that have lost fingers. Two that have lost teeth. Two that have died along crashes.

Getting shocked by ignition systems is on par with stubbing your toe.

I’ve worked as a mechanic and been hit by it before… I don’t think it’s as dangerous as you’d expect from the voltage. I think both the duration of spark, and current are very low.

At one of my first jobs, the workshop foreman would sidle up beside another mechanic who was working under the bonnet, casually put his arm on their shoulder or whatever, then touch a plug. It would make the other mechanic jump, but he himself seemed impervious (well steeled more like) to the effect.

Ive never heard of anybody ever dieing from it, although I could see it happening in freak cases. If I had a pace maker I might be a little more careful but the only real risk I consider from it is a lot of pain and a tiny arc burn where there was electrical contact. If you are dumb enough to purposefully stick your finger in a spark plug hole and crank the engine though I think that is on you. You shouldn't have your hands in the engine compartment at all when cranking a motor unless you are an expert already.

i have a vague memory of either my dad or grandfather working on a car and holding on to a sparkplug to see if it not firing was the cause of the problem. I remember them dropping it and shaking their hands like they touched something hot and saying "no, that's not it" hah.

Captain Pedantic asks, "isn't 'electronic ignition' an ignition system that uses an electronic module instead of physical points?" I've not heard a definition of "electronic ignition" that cares about how the electricity gets to the spark plug. Instead, we are concerned with how we trigger the magnetic field to collapse and makes spark: is it the mechanical opening of a switch, or is it transistors?

And using that definition, we've had electronic ignition commonly put in cars since the 70s. Distributor, or lack thereof, has nothing to do with that definition.

Indeed, I too chuckled at that. Do you remember those hobbyist kits from the 80s for building your own electronic ignition unit? (i.e. points replacement)

As I understand matters, first spark make air conductive (could say, it becomes plasma), and than for some time you need much less power to light plasma.

Very similar physics behave in classic neon lamps - they use short high voltage impulse to ignite plasma, then much less voltage to support it.

So one could make two circuits - one (already existed), will provide enough power to "cold start", other will just provide modulated from waveform voltage (probably, something like pwm).

Sure, second circuit should be fast enough to be in time with sound, but again, as I said, need much less voltage.

I cannot provide exact numbers now, but as I hear, for spark plug like gap at atmosphere pressure, need few kilovolts to spark plasma, and may be within 1Kv to support plasma.

In ICE pressure is much higher, because of this, in electronic ignition usually used up to 100Kv to make spark.

If you could make low pressure environment, ~ 1/100 of atmosphere at sea level, you could probably limit to few hundreds volts for all.

Also exists some chemistry, which make air conductive at much less voltage.

Also exists tricky schemes, where something very similar to AM radio transmitter, made air closer to ignition, and then need much less voltage to make plasma.

Coil-on plug was not terribly common in the 90's. More likely you would have had a "distributorless" ignition system with a coil pack mounted somewhere in the engine compartment and plug wires from that to the engine. Earlier in the 90's you would have still had a distributor but with electronic fuel injection either by direct injection or by throttle-body injection. The only TBI engine I've had was an OBD1 system with a distributor attached to the oil pump. It was built in 1995. The only electronic ignition engine I drove from the 90's was from 1996 and it had an OBD2 system with a coil pack. My first coil-on-plug engine was from 2006.

Otherwise this is a great article.

My son has a Seat Leon MK1 from 2002 and that uses coil-on-plug. The MK1 was released in 1999, so likely at least VW group were using coil-on-plug in the late 1990s.

COP was invented in the 1930s, and first used on automobiles in the 1970s: https://gtc.ca/blog/the-different-types-of-ignition-systems/...

> Earlier in the 90's you would have still had a distributor but with electronic fuel injection

Even by the mid-80's, many European cars were already running this setup, or at least electronic ignition and CIS injection.

I was still a professional mechanic in the 90s. Coil-on-plug was becoming common even amongst American brands, let alone European.

"listen the station in the arc between antenna and grass."

https://www.youtube.com/watch?v=b9UO9tn4MpI

Whichever engineer designed that spark plug should have tested it better to ensure the spark didn't 'wander' around as it's doing!

It's going to be next to impossible to tune an engine properly if the spark location wanders around a few mm for no reason.

I'm thinking 16, as in Volkswagon W16, part harmony on the Queen song.

Link to the original article, so you don't have to agree to the "Autopian"'s douchey "accept marketing cookies or we won't show you the media:" https://newscrewdriver.com/2024/06/08/toyota-sienna-denso-co...

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