DIY fake exhaust tone

[FunInTheSun]

<snip>
Here are a few thoughts that I’ve been running so far:

1) Arduino choice: I am experienced with them, made many home automation devices so far, my own CNC and teaching to students in university. Also I want an instant response, from the moment I turn the ignition or a switch. I can read analog and digital on these boards. There are versions that also have a DAC, so output wav quality is good.

2) OBD reader for Tacho. It will be hard to interface on the Arduino and also the OBD port is hot. An ELM327 always connected can drain a battery in two days.

Try a CAN Bus interface

3) I thought of noise cancelling initially, but I do not have enough clocks and memory to run a windowed FFT on the Arduino to depict the frequencies I want to phase out.

4) Similar to 3) I cannot run a microphone to convert the tone of the engine into RPM, I need something stronger. A Raspberry PI could do that but it boots way too slow.

Have you looked at the ESP32? Dave Plummer (Dave's Garage on YT) has a video out on using certain ESP32 boards with the Arduino development system. If you have the math chops to be thinking about FFT windows, you should consider this immensely more powerful platform. Still Arduino price point, but with a 32 bit microprocessor...


<snip>
9) I will go through a ton of iterations to get it right .
10) I will probably fail many times .

Haha! That's Engineering!

Here's my condensed wisdom on this:
Contained in every solution are the seeds of a new problem.

See comments inline above (italics)

Interesting project.

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[D Fresh]

yeah, parking lots are the kicker. EVs usually do make some noise, but it's pretty subtle compared to most ICE cars. in a noisy environment, you may not hear it.

Modern gas engines are pretty quiet at idle.

And a parking lot can have about 50db of background noise.

At parking lot speeds an ICE car is not much louder than an electric. Most noise from a vehicle at those speeds is tire noise.

 

[onobeka]

See comments inline above (italics)

Interesting project.

I’ve never worked with an ESP32, yet I know them from a distance. They yield higher sampling rate which will be useful!

 

[onobeka]

I seriously doubt we will ALL move to EV's. The movement is bound to fail. Unless, maybe, just maybe if we move toward nuclear energy. I know that for a fact.

Don’t hold your breath o that!

 

[OFC Ranger]

Modern gas engines are pretty quiet at idle.

And a parking lot can have about 50db of background noise.

At parking lot speeds an ICE car is not much louder than an electric. Most noise from a vehicle at those speeds is tire noise.

Unless you own our truck and then your hood is open for some reason.


TICK TICK TICK TICK TICK TICK TICK TICK TICK

 

[onobeka]

Why don't you want to use CAN? Seeed Studio offers a CAN Bus Development Kit which is basically a CAN Bus Shield with the Arduino built-in. Especially if you are only grabbing one message, the decoding shouldn't be that big of a hurdle.
The basics:
https://www.seeedstudio.com/blog/2019/11/27/introduction-to-can-bus-and-how-to-use-it-with-arduino/
The actual device: ($17.90)
https://www.seeedstudio.com/CANBed-FD-Arduino-CAN-FD-Development-Kit-p-4724.html

You should also think about how engine tone changes with load. Full throttle at high rpm doesn't sound like a speeded up version of idle. You may want to select the "Engine Load" value to select tone settings, (or aternate samples), and "Engine RPM" to control frequency. Not sure if the Load message is placed on the bus, but that's the fun part of the project, right?

To do it completely analog, you will probably want to use a high impedance op-amp to sense your selected transducers to avoid loading effects on the sensor and affecting the calibration of the ECM input circuits.

That is something I did not consider. Engine load is definitely not going to depend on the pedal, especially with a manual gearbox. Many times I find myself in the wrong gear if I do not know the road . This may be a big issue.

 

[mtbikernate]

Modern gas engines are pretty quiet at idle.

And a parking lot can have about 50db of background noise.

At parking lot speeds an ICE car is not much louder than an electric. Most noise from a vehicle at those speeds is tire noise.

diff tones, though. EV noises are typically more of a whine, whereas even low powered ICE cars have fan noise and some kind of mechanical sound (pitch varies with engine size and whatnot).

higher pitches are easier to lose in the background.

 

[D Fresh]

ideally thats what we all want, but accidents dont happen when everyone does things right.
just pointing out i never heard the Tesla approaching. Is that my bad, to a degree, i listened to iron maiden far too loud for too long in my youth.
but does it mean i should be rolled under a set of aero wheels for it?
for reference, I have yet to have a close call with a Ford Mustang GT

I've seen pedestrain accidents at parking lot speeds, you'll bounce right off, not go under.

Of course you don't deserve that, but like you said, accidents happen.

You are the only person on the continent who's yet to be attacked by the crowd eater. No need to be stealthy when you're a mass murderer.

 

[D Fresh]

diff tones, though. EV noises are typically more of a whine, whereas even low powered ICE cars have fan noise and some kind of mechanical sound (pitch varies with engine size and whatnot).

higher pitches are easier to lose in the background.

Granted that fans are loud. But most vehicles today are strictly electric fan, not mechanical, it may or may not be on.

Hybrids have been around for over 2 decades. They travel parking lots on electric power only. We've yet to see a back up alarm mandated on them while not running their ICE. And I've heard of no rash of hybrid/pedestrian accidents at the Walmart.

I'm not saying it won't happen. Just that it's completely not needed.

 

[mtbikernate]

that overhanging hood on mustangs will take your legs off. my dad lost one of his when he got t-boned by one when riding a motorcycle.

the crash wasn't the fault of the mustang driver. stop sign was missing, a dumpster was blocking my father's view of the cross street, and he pulled out in front of the mustang.

 

[mtbikernate]

Granted that fans are loud. But most vehicles today are strictly electric fan, not mechanical, it may or may not be on.

Hybrids have been around for over 2 decades. They travel parking lots on electric power only. We've yet to see a back up alarm mandated on them while not running their ICE. And I've heard of no rash of hybrid/pedestrian accidents at the Walmart.

I'm not saying it won't happen. Just that it's completely not needed.

most people are careful when driving in parking lots. but not everyone is. hybrids and EVs now make more noise than they did when they first came out. specifically because they're so quiet. I have no qualms about innocuous requirements that prevent injuries in the first place. also more pedestrians are starting to get accustomed to quieter vehicles in parking lots. when they were newly out and even more quiet, with people not accustomed to the sounds they do (or don't) make, it was a bigger issue. but one that was addressed, in part, with little fanfare.

 

[FunInTheSun]

That is something I did not consider. Engine load is definitely not going to depend on the pedal, especially with a manual gearbox. Many times I find myself in the wrong gear if I do not know the road . This may be a big issue.

Manifold vacuum could be useful as a proxy for engine load (Not sure if this is true for turbo engines, or only for naturally aspirated motors). High vacuum at idle, low vacuum at WOT. Changes are reflected without any change in RPM, which is what you want. Make sure you get a vacuum signal DOWNSTREAM of the throttle plate.

Vacuum (hint: absolute pressure range) transducers are cheap, especially if you can do the basic interfacing / signal conditioning. Some of the available models produce a digital stream output if you prefer that to analog voltage.

 

[D Fresh]

most people are careful when driving in parking lots. but not everyone is. hybrids and EVs now make more noise than they did when they first came out. specifically because they're so quiet. I have no qualms about innocuous requirements that prevent injuries in the first place. also more pedestrians are starting to get accustomed to quieter vehicles in parking lots. when they were newly out and even more quiet, with people not accustomed to the sounds they do (or don't) make, it was a bigger issue. but one that was addressed, in part, with little fanfare.

I don't recall this change in volume that you do. And I would not call the sound of 1000 forklifts to be innocuous at all.

I don't support the addition of stupid laws to the books just to prevent injury from people's stupidity. But as I said, I wouldn't put it past them.

 

[Hellrazor]

Sell it and get a v8 with headers and duel exhaust no cats

 

[got3fords]

Don’t hold your breath o that!

Yeah, I know! The cleanest energy available is not even in the picture.

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