Electronics > Beginners
How much can be reverse engineered from sound ?
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james_s:

--- Quote from: Alex Eisenhut on May 21, 2019, 12:27:53 am ---It's the audio equivalent of cilantro I guess.

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Sometimes I think I'm the only guy out there ambivalent to cilantro, everybody seems to either love the stuff or hate it. I could take it or leave it.
T3sl4co1l:

--- Quote from: james_s on May 21, 2019, 12:11:17 am ---They'll be around for a long time on aircraft, especially turbines. You're not gonna see an electric jumbo jet without a drastic new development in energy storage tech. Liquid fuel has a very big advantage in that the craft gets lighter as you burn it off.

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No need to qualify the statement -- you just won't.  They're hard pressed to win any further gains in efficiency, as it is; even with highly cost-effective and efficient manufacture and charging (say, cheap materials and hydro power, I guess?), the fact remains that, a theoretically perfect battery (perfect in terms of what's on the Periodic Table) is, at absolute best, only just competitive with fuel.  (And the best pair the Periodic Table offers, are not cost-effective elements.)  And indeed, as mentioned, doesn't benefit from the rocket equation (weight falls over time).

You'd much more likely find proposals of CNG (or cryo NG?) aircraft, say?  To even begin to be feasible, that would require the price of natural gas to go near-zero for a viable length of time.  But even so, that has obvious and serious problems, roughly comparable in magnitude to the electric question I think.

The real innovation I'm looking forward to: a reasonably simple, highly efficient method for transforming one or more energy sources (thermal, photo, electric..) into long-chain hydrocarbons.  An ideal example would be a catalyst for a reversible hydrocarbon fuel cell.  Or to put it another way: solve fossil fuels by making them carbon-neutral, so that they aren't "fossil" anymore.

Tim
bsfeechannel:

--- Quote from: Circlotron on May 20, 2019, 10:23:40 am ---A good V8 at 9000+ rpm sounds pretty cool IMHO.

https://youtu.be/fbTRaDQ1tJA

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It reminded me a little bit of our old floor polisher when I was a kid. I don't know why.

vk6zgo:

--- Quote from: T3sl4co1l on May 20, 2019, 03:57:48 am ---
--- Quote from: Brumby on May 18, 2019, 06:23:52 am ---If you want to understand just how much the exhaust system does, try driving a vehicle with bits of it missing...

The abovementioned mechanic did LPG conversions and sometimes there would be a need to alter the path of the exhaust system to get around the LPG tank.  I was the one usually chosen to drive these vehicles over to the exhaust place - and let me tell you, you get a REALLY good first hand lesson in the accoustic output of even the most moderate engine - especially when under load.  As a result, my driving in these situations was extremely conservative - but there was still a bridge over a railway that had a steep approach and the noise was intense.

Sometimes the only bits of the exhaust still attached were the manifold, engine pipe and catalytic converter.  BIG noise!  (and, yes, I was constantly looking in all directions for any police interest - which I never encountered, thankfully)

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Had my exhaust replaced recently, had to limp around town with nothing on while they were getting parts in.  Even the weedy engine in my Toyota sounds like a hotrod* when it's loud and open like that.

*A hotrodded lawnmower, to be more honest / accurate. ;D

Also quite a difference; the previous system I had, was welded from pipes and parts.  In particular it was missing a mid-line resonator.  Never quite sounded right.  (This time around, it's all aftermarket or OEM parts, close enough to original. Sounds about right.)

Also a little surprising how much, and how little, difference can be made from little leaks here or there.  Rusted out pipes tend to get loud, and add a rougher sound with more hiss (modulated hiss -- turbulence on the pulses).  Sound from underneath or behind the vehicle tends to carry pretty well.  OTOH, leaks in the engine bay don't seem to do much, presumably as the sound is forward-facing and reasonably well absorbed and scattered by everything in there.  (They weren't able to seat the downpipe quite right so I had this going on, before getting it re-checked.)

Tim

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My 1999 Toyota Camry sounds like an antique "sewing machine" externally at start up.
I can usually recognise Toyotas from around that year, as they all sound like that.
Strangely, my Camry sounds beautifully smooth & nearly silent when cruising on the open road.

My old Leyland P76 V8, with an after market twin system sounded great --- classic "tuddy, tuddy" sound when cruising the back blocks of the WA wheat belt.

The kids loved it--- they would sit in the back, with the windows down, revelling in the sound, & the air rushing in.
They liked to get in & out through the windows, "Dukes of Hazzard" style!

When I was a kid, I particularly liked the old "sidevalve" Ford Customline exhaust sound, too.

The sound that really gets my attention, however, is a big old turbocharged Dorman Diesel firing up.
When this happened, it was when a power fail occurred, so there is an element of "Pavlov"s dogs" in it!

The next place I worked had Detroit Diesel Standby plant, much more efficient, but for character, they never quite matched those scary old "Brit beasts"!
Liam:
I do not understand the point in making this. Do you need a sound? It can be created using the program on the computer. I do not understand the purpose of which you are pursuing :) Explain in more detail what you want and why.
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