the POPCORN machine (a different burst box?)

[iainpunk]

so i was looking up a datasheet for a pedal i was taking inspiration from, and came across this:



at first i could control my laughter after reading the 4th feature, ''popcorn noise''. 

for those who don't know, popcorn (burst) noise is basically a very slow squarewave that switches from low to high in random intervals, within a certain range.

about 10 minutes later i got the idea to find a chip that does have ''popcorn noise'' and make a popcorn pedal that just adds popcorn sound to the clean signal.

but then i wanted something to control the chance of a pop, to get more or less frequent pops. also an amplitude control and possibly a filter to give the pops a softer character.

i know that its easy to create random bits at fixed intervals, but that's not really what im looking for...
so does anyone know a simple way to create this kind of burst noise, with random time intervals, but somewhat controlled?

cheers, Iain

[Rob Strand]

It's a genuine technical term.   

It tries to categorize noise that comes in bursts and is found in semiconductors.   It's different to filtered white noise like pink noise and 1/f noise.    White noise etc are more like rain whereas popcorn noise crackles like popcorn or perhaps like crackles on a wood fire.

https://duckduckgo.com/?q=1%2Ff+noise+vs+popcorn+noise&ia=web

[blackieNYC]

Sounds like a fun random LFO also.

You pour the corn and vegetable oil on, yes, a copper coil...

[duck_arse]

Because it is uncommon, popcorn noise is not discussed further.

[iainpunk]

thanks for the replies

It's a genuine technical term.   

It tries to categorize noise that comes in bursts and is found in semiconductors.   It's different to filtered white noise like pink noise and 1/f noise.    White noise etc are more like rain whereas popcorn noise crackles like popcorn or perhaps like crackles on a wood fire.

https://duckduckgo.com/?q=1%2Ff+noise+vs+popcorn+noise&ia=web

yeah, i know, ive been reading up on it, quite an interesting topic.

Because it is uncommon, popcorn noise is not discussed further.

where'd you get that quote from?

now im just trying to figure a way to reliably fake it, with a certain degree of control to it as well. im trying to sample/hold a really fast triangle osc., let the cap drain through a resistor and only sample the triangle again under a certain threshold, so the pseudo random sample level of the noise determines the time it takes to drain.

cheers

[iainpunk]

Sounds like a fun random LFO also.

You pour the corn and vegetable oil on, yes, a copper coil...

this is not another burst box thread! (it kinda is, but i dont want it derailed like the other)

cheers

[mozz]

I've got some popcorn noisy germanium transistors if you want them. 

[Rob Strand]

now im just trying to figure a way to reliably fake it, with a certain degree of control to it as well. im trying to sample/hold a really fast triangle osc., let the cap drain through a resistor and only sample the triangle again under a certain threshold, so the pseudo random sample level of the noise determines the time it takes to drain.

cheers

The old lingo was "random telegraph signal".  Do a search on

popcorn noise random telegraph signal

See the pics on document pages 79, 80,
https://pure.tue.nl/ws/files/3727869/94820.pdf

I'm quite sure you will find stuff on simulating it.  Doing it with a circuit might need a bit more work.  Something like a noise source, or filtered noise source, feeding a detector with a threshold like that on a Geiger counter to produce a digital output.  There's quite a few DIY Geiger counter examples in old electronics magazines, say from the 60's and 70's.

[duck_arse]

thanks for the replies

It's a genuine technical term.   

It tries to categorize noise that comes in bursts and is found in semiconductors.   It's different to filtered white noise like pink noise and 1/f noise.    White noise etc are more like rain whereas popcorn noise crackles like popcorn or perhaps like crackles on a wood fire.

https://duckduckgo.com/?q=1%2Ff+noise+vs+popcorn+noise&ia=web

yeah, i know, ive been reading up on it, quite an interesting topic.

Because it is uncommon, popcorn noise is not discussed further.

where'd you get that quote from?

.....
cheers

It's a genuine technical term.   

It tries to categorize noise that comes in bursts and is found in semiconductors.   It's different to filtered white noise like pink noise and 1/f noise.    White noise etc are more like rain whereas popcorn noise crackles like popcorn or perhaps like crackles on a wood fire.

https://duckduckgo.com/?q=1%2Ff+noise+vs+popcorn+noise&ia=web

third return summary.

[iainpunk]

I've got some popcorn noisy germanium transistors if you want them.

i want a to have some control over the popcorn frequent-ness i am afraid that popcorn noisy transistors leave that to be desired.

am already busy designing a more controllable random interval generator, but not yet convinced that i know how to do it.
i also plan on partially gating it some way so it pops louder when playing, and softer when not playing, with some random variance to it volume as well, something i already know how to do

Relative differential amplifier with a slightly offset bias, the amount of bias offset determines the un-gated pop volume, while if its biased in the middle, the pop volume is dependent of where the wave is at that exact point in time, because it inverts the signal every pop.

to be honest, i have a better idea about how i want it to sound and look than i have on the actual schematic, which is the opposite of how i normally do it. (red/white stripes and a bold popcorn logo on it, and a few actual poped corns glued to the top)

cheers

[mozz]

I've also seen transmitters that use diodes for a noise source.

[eh la bas ma]

(red/white stripes and a bold popcorn logo on it, and a few actual poped corns glued to the top)

For your artworks :

https://www.madeincolorado.com/colorado-jack-white-cheddar-jalapeno-popcorn.html
(off-topic : check this website, food looks expensive in Colorado, but they're doing a good price on buffalo sausages. They even have "handcrafted Deer Antler backscratcher" in unusual gift section !)

or




"Legendary" looks smoother than the flashy "Gourmet", in my opinion.

[iainpunk]

I've also seen transmitters that use diodes for a noise source.

yeah, i was looking in several avenues to get noise that also has a bandwidth that extends well into the sub-audio rate. was talking to a friend, he said some types of diodes seem to have a lower extension than others, but i guess ill just have to try and experiment with several methods of creating noise, but ill probably go with thermal noise, as it purportedly has the best low end extension.

(red/white stripes and a bold popcorn logo on it, and a few actual poped corns glued to the top)

For your artworks :

https://www.madeincolorado.com/colorado-jack-white-cheddar-jalapeno-popcorn.html
(off-topic : check this website, food looks expensive in Colorado, but they're doing a good price on buffalo sausages. They even have "handcrafted Deer Antler backscratcher" in unusual gift section !)

or




"Legendary" looks smoother than the flashy "Gourmet", in my opinion.

those popcorns look to be delicious, but thats an awfully odd website, they literally sell shit... cool

if i ever travel to the USA, the state of Colorado is high up on my list, as i really want to visit South Park, although its not really a town, but more a literal park, still, that show shaped my life and taught me a lot of moral and life lessons, and i want to see that.
i also wanted to see Columbine Highschool ever since i saw a documentary about Eric and Dylan.
the state flag is also quite cool, its just the right balance between quirky and good design. (most quirky flags are just designed badly.)

cheers

[ElectricDruid]

You could do this with a filtered noise source and a comparator. Because of the filtering, the noise source will mostly stay close to the centre value, but occasionally will wander further away and make the comparator flip. More filtering makes that less likely.

I did a similar thing in software to create this, but it doesn't offer any external controls:

https://electricdruid.net/adding-vintage-hiss-crackle-and-pop/

This started off as the Pentanoise five-channel noise source, but then two channels got repurposed to provide different rates of pulse like you're talking about, and I used those to control the other noise sources. Of course, you could use the 'Pop' and 'Crackle' signals directly. I didn't experiment with that much, to be honest.

If I was doing it with knobs on, I'd use something like the Pentanoise to provide noise sources, and then filter them with simple RC filters using pots, and then feed that to comparators to get back to digital outputs. Then mix the digital outputs to taste!
Ummm! Lovely popcorn!

[anotherjim]

Colorado Jack White Cheddar & Jalapeno Popcorn

Is this the Burst Box connection?
Or did the web catalogue forget it's "Colorado Jack. White Cheddar & Jalapeno Popcorn"?

[iainpunk]

You could do this with a filtered noise source and a comparator. Because of the filtering, the noise source will mostly stay close to the centre value, but occasionally will wander further away and make the comparator flip. More filtering makes that less likely.

I did a similar thing in software to create this, but it doesn't offer any external controls:

https://electricdruid.net/adding-vintage-hiss-crackle-and-pop/

This started off as the Pentanoise five-channel noise source, but then two channels got repurposed to provide different rates of pulse like you're talking about, and I used those to control the other noise sources. Of course, you could use the 'Pop' and 'Crackle' signals directly. I didn't experiment with that much, to be honest.

If I was doing it with knobs on, I'd use something like the Pentanoise to provide noise sources, and then filter them with simple RC filters using pots, and then feed that to comparators to get back to digital outputs. Then mix the digital outputs to taste!
Ummm! Lovely popcorn!

i was talking to my friend some more and i think im going with transistor noise, a shit-tonne of gain, and a Schmitt trigger to get really stable high and low levels.
the way im mixing the random square with the clean signal is with this contraption:




instead of just adding pops, it also inverts the signal. this limits the amplitude of the 'pops' to the wave's amplitude, and also the bias offset of the input signal determines the amount of DC pop. the phase inversion wouldn't be to noticeable as it happens at such low rates.
this is just a proof of concept, a mock-up basically.

cheers

[amptramp]

If you look at popcorn noise on a scope, you see the signal switching between two discrete levels like 1.37 volts and 1.48 volts repetitively.  The popcorn noise mechanism appears to be related to current being forced to move at random across inclusions in the semiconductor, which is why the two discrete values keep showing up.

If you want to simulate it, you can make up a pseudorandom noise generator from shift registers and XOR gates and use the output of on of the shift register digits as the controller for an added current into a linear amplifier.  You can change some characteristics by changing which stage of the shift register does the driving and the oscillator rate that clocks the registers.

[Kipper4]

Surprised no one suggested the Stomplfo.

[iainpunk]

the thing with both the stompLFO and the shift and XOR is that they both have a regular frequency with random high/lows. i want the interval to be random.

the method i described above is effective enough. to re-create natural popcorn noise isnt the goal here, getting a pedal that sounds like popcorn is, independent of how accurate it is to popcorn noise
it stops being popcorn noise if its wanted, then it becomes just popcorn sound.

cheers

[Phend]

Prize inside every stomp box ?