When I was 12 years old (55 years ago) an uncle gave me an analog synthesizer kit. I remember the noise source circuit included a transistor with no connection to the base input. Now I understand why! Thanks.
Just thought of this, but a less cruel analogy for the breakdown voltage might be waves breaking over rocks. 🌊🪨 The rock (transistor) will block a wave up to a certain height (amplitude), but water above that height will crest and crash over the rock (breakdown). Going a step further with this analogy, over time, the waves crashing will erode the rock down (burn out the transistor). How quickly that happens depends on how big the waves are, and how strong the rock is. Love these simple filter circuits! 👍️
Thanks for adding shelf filters to my bag of analog tricks! I already knew about the "overvolted transistor as a noise source" thing but the filter stuff was new to me and really interesting. I need to get myself an audio range spectrum analyzer now ...
9:15 The resistor at the top-left corner seems connected to the negative rail, although I understand is the transistor emisor and it should be connected to the positive trail instead.
@@MoritzKlein0 No problem, I just wanted to be sure I understood, as that didn´t match what I expected :) Thank you for your videos! They are very useful and informative.
Interesting how a high-pass filter and an AC coupling capacitor are basically the same arrangement. Presumably with a coupling capacitor, you pick a value so that the cutoff is well below audible frequencies?
yes, and in fact a DC offset shows up as a 0Hz frequency in a fourier transform. with a coupling cap the resistor part of the HP filter is distributed as parasitic resistances to ground in the nearby components.
I made something almost exactly like this a couple of years ago, trying to make a noise generator function for a function generator (I'm still) building. It was most instructive learning how to do that, but I wish I had your video back then to explain it to me, as this is the best explanation I've seen all together in one place. I'll add a blue noise function now too (I just had white and pink before). For the pink noise, I did try a 6-stage shelf filter to try and get more accurate, but it never seemed to work as well as the 3 stage one... probably because the attenuation was too much.
Hi! Can you please make big comparsion between various noise sources in controllable breakdown mode? Such as zener, detector diodes, transistors; both silicon and old germanium ones. And also LEDs with different semiconductor types. I wonder for differences in spectrum.
Tone changes both with the type of semiconductor, and the current it is driven at. Because of this your request is difficult to fulfill, but if you search sites of guitar distortion effect builders you will find volumes have been written on this topic. Often, guitar players have multiple noise generating effects which operate on PN junction breakdown because of their different qualities. You should experiment and select based on your likes. Noise is very individual.
I don't understand, on the schematics it seems like the emitter should be connected to +V through the resistor but on the breadboard it is connected to ground (the blue breadboard rail). How can this still work?
It should be noted that synth makers tested their transistors and hand selected the worst, dirtiest transistors for use as noise sources. Some makers even switched noise sources as the task of selecting proper noise transistors got harder because of expanded sales volume and improvements in transistor manufacturing. The two most common substitutes were Zener diodes and shift register based digital noise chips. All have different tone and texture, but transistors are the most variable in manufacturing.
I love the content. Very well done. One minor point. The sine wave is a single bin in the frequency spectrum. If it's more than one bin, that is a side effect of how the data is sampled. The only reason I think this is significant is because it further accentuates your point that a sine wave is very frequency specific, as opposed to the noise. Thanks so much for the great content.
Fascinating, thank you Moritz! I'd have just tapped into the noise source, let it run through a 6db/oct filter and then mixed the source and the filtered output together - having watched the video I'm confident that that wouldn't work now 😁
When doing the schematic myself, I was wondering why the noise was off-centered. I finally understood by comparing with Rene Schmitz schematics. We need a 220nF capacitor betweeen the 680 ohms resistor and ground to compensate for the offset. Seems the zero is not perfect on op amps, and it is very noticeable due to the high gain. At least this is my interpretation for that issue.
To make a 3db/oct slope. - Make a parallel section: one side with the unfiltered noise signal, one side with the 6db/oct slope filter - Invert the phase of the filtered signal, and reduce the amplitude by whatever factor is equivalent to 6 decibels of perceived loudness (possibly 50%?) - Recombine the signals, and you'll have a 3db/oct slope filter. Thats how i would do it in my DAW if i needed to make a 3db/oct filter and only had access to a 6db filter. It'd be the same as routing the audio from a parent track to a parallel send track, putting a 6db/oct filter on the send, inverting the phase and lowering the output by 6 decibels. :D
Thank you very much, Moritz, thanks to your Channel i started creating my modular synth:according your video and shemes already assembled and working 2 vco(first one is not so stable keeping octave, seems because of component) second vco is stable tested with external midi keyboard +doepfer midi to cv or with korg sequenser with cv/gate out, also assembled VCA, ad/sr, and most Hard for me - ladder FILTER, all works good, some moments out of range - but it is because of components i used.
I love these videos and they are always super high quality and easy to understand. The explanations really do showcase the fundamentals of audio circuits! I wonder if you could improve your top-down shots with a Telecentric Lens? It would remove the perspective distortion on your breadboard, allowing the viewer to see the circuit in "2d", orthogonal view. So the resistors and cap leads aren't out of place. I suppose you could get the same effect much more cheaply with a telephoto lens placed far away, at a high zoom...
Usually, white noise is noise containing random frequencies with equal energy per frequency, whereas pink noise is noise containing random frequencies with equal energy per octave, so, pink noise tends to sound like it has more bass frequencies in it than white noise does, blue noise basically contains random high frequencies in it, red noise contains random low frequencies in it, there's also brown noise, or Brownian noise too.
These videos are really great Moritz, but one thing that's missing (unless I missed it) is what kind of output module we need to connect our audio to an amp, headphones, or computer's audio in without blowing anything up. Some YT videos just say "don't worry, connect it up", but having 10V p-p signals going into a laptop or audio amp sounds like it might do some damage....? PS: A red wire connecting to ground on the breadboard? I thought you were better than that.... ;)
The classic way noise is generated in a Synthesizer is by the use of a reverse-biased Diode junction, or a reversed-biased transistor B-E junction, you do have to hand-select a diode or transistor to find one that generates a good amount of noise though.
I had never heard of blue noise before. I have also heard some other "colors" mentioned, but have no idea what their specifics are. Some years back, I built a device that used a 12 volt power supply and utilized the base-emitter reverse breakdown mode as noise sources. At that time I had those transistors in sockets, with the thought of selecting them for maximum noise output. This was probably not a good idea, as Ive since learned that subjecting a transistor to that kind of reverse breakdown has a permanent and adverse effect on the transistor's beta. Did you select a particular kind of transistor as being optimum for this application or did you just use whatever you had on hand?
oh interesting. so the transistors get "worn down" by producing noise? i wonder if they'll fail over time. in my case, i tried both the 2N3904 and the BC548. the former's output is super quiet, while the latter reliably gives you really strong noise. so i kept using the BC548 for noise purposes going forward, and it hasn't failed me so far!
@@MoritzKlein0 Not "worn down", just that running them in base-emitter reverse breakdown does something irreversible to them, I am not clear as to the details of it.
Hello mister Moritz Klein, WOW, so many smart explaining and analogies in this video, I learned so much from only two of your video's... Amazing. Great explanation and instructions and the video's themselves (the production) is exceptional, you earned yourself another subscriber !!
@@MoritzKlein0 Is there a site/service where I could upload the schematics and they'd produce the entire devices with SMT components, not just the board?
I've used all your components and have used the exact breadboard layout for the white noise circuit. I get white noise but it's very quiet. I'm using an 8ohm speaker for my output. Any suggestions on how to make this much loider
@@MoritzKlein0 also curious what the 100k resistor is doing, maybe i misunderstood that part of the video. what would happen if its a different value? or there was no resistor at all? im trying to put together a white noise circuit of my own, but i have a different transistor on hand so im curious what part it plays.
Nice! Will be looking forward to the sawtooth to triangle video. I have built your oscillator with the old saw to triangle converter, but it kinda has some high frequency content due to the transition between up and down not being perfect
Hm, the avalanche breakdown noise is in fact shot noise with a certain characteristic. The charge carriers have to overcome a certain potential barrier to initiate a cascade of secondary charge carrieres. This means, shot noise is allready "coloured". I prefer thermal noise (of a metall film resistor or a low power light bulb) as source for a white noise generator, because this is real white noise with an even frequency distribution.
Great video, thanks. Is the junction breakdown really a white noise source, how do we know it isn't coloured already (by the physics of electrons etc)? A pseudo-random generator such as a 32-bit binary shift register with XOR gates could be another way to generate an effective large-amplitude audio white noise source.
6:41 On the breadboard the emitter is now connected to ground through the 100k resister and the gray wire. I'm a bit confused. Very informative video nontheless!
Great video! As all your previous, love them! Just wondering, the "white noise" inputs to pink and blue, are they directly connected to the white output or through a buffer? My feel from the video is that there is no buffer in between, just straight on from the white output?
I've been playing around with this circuit for a couple of days. I am using a 2N3904 transistor so it "could" be different from the BC548 or others. I needed a lot more gain in the white noise to get good enough levels. I added a second gain stage with a voltage gain of 32 to get close to what I expected (about 7.5V peak). The GBW of the transistor is 3 MHz. The gain in the White noise part of the video is set to 148 (100K feedback, 680 to GND. With the 3 MHz GBW, that would be a bandwidth of 22 KHz. Seems OK for Audio. However, with a gain of 148, and an offset voltage of, say 3 mV, is a DC offset in the output of around 0.5V, which is what I measured. I tried a TL084 with slightly better results. I ended up adding an additional 100 ohms to ground (dropped the 680 to 560) and a 50K trim pot with 220K to the wiper (the classic circuit for trimming out offset errors). This was enough to easily trim out the offset voltage error. Using the White output to drive the unity gain of the Blue output didn't have enough amplitude. For that I changed the unity gain buffer to a gain of about 3 (24K feedback, 12K to ground), That was about right. The pink level was WAY too low. I added amplification there as well. Something around 16x was too much (100K/6.8K). I'll probably raise the resistor to ground to 10K and call it good. All of this to ask this question - I expected that the RC values in the Pink noise circuit would be somewhere near the corner frequencies but they are WAY off what I expected. For instance, R=2000 and C=330pF is up around 1.5MHz. The other end R=51K, C=33nF is at 594 Hz. What am I missing here?
I ran an LTSpice simulation and the Pink circuit works just as described in the video. I re-did the RC calculations adding in the 100K and got something like the video (corners at 200Hz, 2.7KHz, and 29KHz.) Perhaps that 'sthe right way for me to see the "why" this circuit works.
unfortunately, the 2N3904 produces barely any noise. i've run into the same issue. if you switch it for a BC548/547, you should get much better results.
Can all 3 noise sources be built into one module by combining their filter inputs after the first buffer and using a switch to select the outputs? It seems like the filters might interact.
Ive made this circuit with correct values, white is working well and is stable, pink works but after about 15seconds it starts breaking down into a crackle, dropping from 4v peak to peak to 0v. I didn’t have foil caps for the filter, so I used 2 film caps and a ceramic… could this be the problem? Turning the power off and back on brings the pink noise back but it only lasts a few seconds.
The emitter is not connected to ground. The triangle pointing upwards is often used as the symbol for Vcc. Generally, ground is indicated by a triangle pointing downwards. Or, as in this video, ground is represented by three stacked horizontal lines.
I've tried to simulate the white noise circuit on TINA TI and i cant get the same response that you seen on the osciloscope, can you help me with that. I am trying to build and white noise generator to simulate the response of a Sallen-Key low pass filter.
I loved the video, but have a question. You said the high pass filter had a cutoff of 1.6hz. I've been working on a random LFO that outputs voltage from 0v to 3.3v (arduino based) and I would like to shift it so it is centered on 0 volts. Could the capacitor/resistor be changed to allow much longer periods in the + or -, like 20-30s? I'm guessing not, but I'm a noob when it comes to designing circuits. Or could the arduino be run at 1.65+ as the positive and -1.65v at the ground?
yes sure, that'll work. just use a bigger resistor or capacitor. you can calculate the cutoff frequencies of different r/c combinations with this tool: sim.okawa-denshi.jp/en/CRtool.php
Hallo Moritz. Is it possible to obtain a blue noise output, by feeding + an - opamp inputs with white and pink noise respectively, in a differenciator configuration ? Just an idea to save some components. And what would be the result with pink and blue ? White output again ? Thank you.
The fourier transform is linear, so I would expect subtracting pink from white to work if the amplitudes match up. Not sure how it would work out in practice though with the filtering involved etc
Pink noise should be enough to make blue noise, and vice versa: -3 dB/octave is hard and 3 dB/octave is also hard, but if you have one then you should be able to get the other using simple filtering. So at least in theory, if you pass the pink noise through a 6 dB/octave high pass filter (differentiator), then you should get blue noise. And if you pass blue noise through a 6 dB/octave low pass filter (integrator), you should get pink noise. It doesn't have to be a perfect integrator/differentiator, just act more or less like it over the frequency range that you care about. In practice, you might get some trouble because some parts of the input signal are quite weak, and those are the ones that you would be amplifying the most, but I think it could work.
@@RayMcNamaraMusic Yes! But the more I thought about it.... wouldn't you need two more op amps? When I picture it in my head I'm visualizing basically building everything in the video again.
@@mathieumartin9344 You don't have to build the whole thing in duplicate just for another filter type. You could use the same white noise source and send it to the BP filter, which is basically a LP and HP in series. You could pull that off with a single opamp.
Awesome, Moritz!! Thank you! Moritz, what type of capacitor do you use and are they better suited for the purpose of audio? I would like to see a brown noise circuit *and* a circuit that will give an animated sweeping effect with variable rate. As well as a gated input. *Please.*
You can try to use any type on non polarised capacitors(so electrolytic and tantalum don’t work) for audio, even the cheap ceramic ones in most cases. The one he uses are called film capacitors or foil capacitors, they are meant to be better for audio but are also significantly more expensive. It maybe worth trying to use the ceramic ones on a breadboard or something, if the circuit sounds fine you can save some money
Also for brown noise, it’s just a simple 6db/oct filter of white noise en.m.wikipedia.org/wiki/Brownian_noise . so. A simple 1pole passive low pass filter with 1 resistor and 1 capacitor will work
@@woosix7735 the main downside of ceramic capacitors is that they are microphonic. The really cheap ones have terrible tolerance, temperature coefficient, and voltage coefficient too.
Twin T's are probably a really great place to start, combined with the blue"ish" noise, you are on the way to old school transistor rhythm machines. I wish the days of old with electronic magazines "build your own rhythm box" were still commonplace. While they were still published when I was really young, by the time my teens rolled around, It was the sparse articles in electronic musician (diy level converters and the like)
I would like to see a 7/15 bit LFSR digital noise generator. I tried with what i had, a 74HC595, it didnt work well, using external clocks would make the chips unpredictable. Im gunna try again with a CD4094
15 bits is probably too small and the pseudorandom pattern will repeat every second for a 32KHz clock. Use a 32bit LSFR or bigger for a more random output. This is even easier with a small micro and a bit of code.
@@mustang2440 I see 32bit too big for audio purpose, yes it can give a cleaner sounding "white" noise with more randomness, but I mostly care about the harsh digital noise. I'm using 15bit because its only 2 chips and flipping a switch turns it into a 7bit for harsher metallic sound. the usually clock I use ranges from 0.1Hz to 10kHz so the repetition is minutes to seconds and with modulation that's even less noticeable. I have the schematic if your interested
white noise is an analogy to white light. in white light, every wavelengthe(frequency) is present with the same amplitude. with white noise, all the frequencys are also present with equal amplitude. for the other colours of noise dont realy have an optical analogue, but blue light is higher frequency and red light is lower frequency, so kinda similar to noise colours.
Hey Moritz :) Thanks you soo much for your awsome and also inspiring videos. I'm fully pumped building my own stuff along with your vids. One thing that is rather confusing for me though is, ordering all the components. I mean, i know how placing internet orders work :D but I mean, do you buy your components normally in bundles? What sources can you recommend (in germany / austria) and what kind of kit (like resistors, capacitors, potis, diodes etc.) would you recommend for a beginner like me? Thx in advance
the white noise is the same noise than a television whitout antenna , and looking at osciloscope, the white noise rises amplitude in high frequencies, and pink noise has all frequencies at same level ...
The shelf filter is a really cool concept that I’d never really heard of, and it was really well-explained. But why can’t you just mix the original input (the white noise) with the 6db/oct filtered output so it’s like only 50% filtered, 50% dry signal? Wouldn’t that be an easier way to get 3db/oct, hardware-wise?
Exactly my thoughts, then with a few pots you could vary from -6dB HP to -6 dB LP, sweeping through blue and pink spectra and getting a BP filter too. I imagine you don't have to worry about phase issues at all since we're just mixing noise.
aww man, this doesn't work very well with 9v batteries, just tried it, it needs the 12V. Edit: you can hack it to work by connecting the base of the transistor(middle pin) to the negative supply insted of groud. It jusses the transister up with 18V insted of 9V
@@MoritzKlein0 no I havent tried that. thinking about this probably every transistor is going to have different brekdown voltage and noise volume charecteristics, because it's not an intended use and is not spesified by the manufacurer. you just have to try a bunch of stuff untill it works i guess
ruclips.net/video/0yB_h_wFkh4/видео.html - Why was that transistor connected to the ground from 2 sides? And better question: Why was it still working?
good question! because i started recording video and audio separately, and i messed up here. (the audio take is from a working version of the circuit setup.)
I've just made the white noise schematic with tl072 op-amp but no noise output. I'm getting 11.3volts at the output but no audible noise. Any suggestions, anyone?
I am not very impressed, I am a chartered electronic engineer and this is mainly unguided and misleading. Voltage does not push current through, current is drawn by a load, voltage is like a bucket of energy. Energy takes the path of least resistance in electronics, as in all areas of life, so flows into the load based on the load. The breakdown you are witnessing is not some cruel effect, it is called the zener effect and this phenomena is a fundamental building block of electronics and has been for nearly 100 years. Providing the series resistor limits the current then the reverse voltage semiconductor will stay in those conditions indefinitely. Transistors do not give white noise, low frequency is made up of flicker noise and higher frequency is thermal noise (thermal noise is very close to white noise). You can tell by looking at your oscilloscope waveform the noise is not white (as it is not equally distrubited positive and negative around 0V)... It sounds grainy in comparison. Opamps must ALWAYS have a decoupling capacitor for operational stability and for rejecting unwanted pickup from the external fields all around. Breadboard is not good for prototyping analogue electronics, or digital electronics. They look nice though, and they are fun to poke things into. According to the maths your 100k/33nF filter only gives 26dB of rejection at 1kHz, so the output will not be flat, there will be a 1kHz component at around 1/20th of the input signal size (20dB +6dB is equivalent to X10 X2). With 1kHz and 100k/33nF the output waveform will be a triangle wave, but this is only based on the relationship between the 48Hz f-3 of the filter and the signal frequency. If the signal frequency is changed then the waveform shape will change. There is an IEC standard filter for generating pink noise, I don't know why you would want it unless you are soak testing/running in loudspeakers you are selling. What is your purpose for making a pink noise generator? Ading a 10k resistor as a zero (shelf) into the response does not give a square wave output, it gives a distorted sawtooth that is around twice the peak voltage of the previous circuit. This is also not just a potential divider, there is an RC which represents a time constant (charge time) and a filter with a complex mathematical pole zero equation that allows us to model gain and phase vs frequency. It seems you are not educated or experienced, I don't understand why you would want to teach or sell designs based on this.
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When I was 12 years old (55 years ago) an uncle gave me an analog synthesizer kit. I remember the noise source circuit included a transistor with no connection to the base input. Now I understand why! Thanks.
Just thought of this, but a less cruel analogy for the breakdown voltage might be waves breaking over rocks. 🌊🪨 The rock (transistor) will block a wave up to a certain height (amplitude), but water above that height will crest and crash over the rock (breakdown). Going a step further with this analogy, over time, the waves crashing will erode the rock down (burn out the transistor). How quickly that happens depends on how big the waves are, and how strong the rock is. Love these simple filter circuits! 👍️
Thanks for adding shelf filters to my bag of analog tricks!
I already knew about the "overvolted transistor as a noise source" thing but the filter stuff was new to me and really interesting.
I need to get myself an audio range spectrum analyzer now ...
9:15
The resistor at the top-left corner seems connected to the negative rail, although I understand is the transistor emisor and it should be connected to the positive trail instead.
yeah my bad - was the first time i filmed and recorded audio separately
@@MoritzKlein0 No problem, I just wanted to be sure I understood, as that didn´t match what I expected :)
Thank you for your videos! They are very useful and informative.
I love how complete and clear your explanations are! This video helped me understand a lot about high and low pass filters.
19:36 thank you, had little hop that this video about electronics would actually help me in Image processing both are signals after all.
Interesting how a high-pass filter and an AC coupling capacitor are basically the same arrangement. Presumably with a coupling capacitor, you pick a value so that the cutoff is well below audible frequencies?
It's not just basically the same, it is 100% the same
yes, and in fact a DC offset shows up as a 0Hz frequency in a fourier transform. with a coupling cap the resistor part of the HP filter is distributed as parasitic resistances to ground in the nearby components.
I made something almost exactly like this a couple of years ago, trying to make a noise generator function for a function generator (I'm still) building. It was most instructive learning how to do that, but I wish I had your video back then to explain it to me, as this is the best explanation I've seen all together in one place. I'll add a blue noise function now too (I just had white and pink before). For the pink noise, I did try a 6-stage shelf filter to try and get more accurate, but it never seemed to work as well as the 3 stage one... probably because the attenuation was too much.
yay ! white blue and pink !🏳⚧
I've learned so much from your videos, thanks.
such simple clear explanations, awesome content
I love this channel so much. Thankyou for feeding my engineer brain a delicious 3 course meal.
Hi! Can you please make big comparsion between various noise sources in controllable breakdown mode? Such as zener, detector diodes, transistors; both silicon and old germanium ones. And also LEDs with different semiconductor types. I wonder for differences in spectrum.
Tone changes both with the type of semiconductor, and the current it is driven at. Because of this your request is difficult to fulfill, but if you search sites of guitar distortion effect builders you will find volumes have been written on this topic. Often, guitar players have multiple noise generating effects which operate on PN junction breakdown because of their different qualities. You should experiment and select based on your likes. Noise is very individual.
hell yeah, trans noise generator
Lol
you called?
You're like the ben eater of analog
I don't understand, on the schematics it seems like the emitter should be connected to +V through the resistor but on the breadboard it is connected to ground (the blue breadboard rail). How can this still work?
It should be noted that synth makers tested their transistors and hand selected the worst, dirtiest transistors for use as noise sources. Some makers even switched noise sources as the task of selecting proper noise transistors got harder because of expanded sales volume and improvements in transistor manufacturing. The two most common substitutes were Zener diodes and shift register based digital noise chips. All have different tone and texture, but transistors are the most variable in manufacturing.
LFSR is by far the easiest and most controllable way to do it, yeah, but I guess many people might find it boring
I love the content. Very well done.
One minor point. The sine wave is a single bin in the frequency spectrum. If it's more than one bin, that is a side effect of how the data is sampled. The only reason I think this is significant is because it further accentuates your point that a sine wave is very frequency specific, as opposed to the noise.
Thanks so much for the great content.
Fascinating, thank you Moritz! I'd have just tapped into the noise source, let it run through a 6db/oct filter and then mixed the source and the filtered output together - having watched the video I'm confident that that wouldn't work now 😁
hmm maybe if you weigh the two signals 2:1 in the mix? something to try!
@@MoritzKlein0 if I had more of a clue than I have and a way to test properly I would now that you've said that!
I am not 100 sure but this may not work perfectly, becase there is phase shifting from by the filtering the signal. worth trying though
it should again look like a shelf filter, so I don't think you will see much in component savings
ah yes thats true. log scalle kinda missleads you there if you dont know what you are looking at
When doing the schematic myself, I was wondering why the noise was off-centered. I finally understood by comparing with Rene Schmitz schematics. We need a 220nF capacitor betweeen the 680 ohms resistor and ground to compensate for the offset. Seems the zero is not perfect on op amps, and it is very noticeable due to the high gain. At least this is my interpretation for that issue.
Mate, I have learned so much from you. Keep doing what you are doing and I will always support!
18:49 What program and setup did you use to get the spectral view of your signal?
this is the stock spectrum analyzer plug-in from ableton! i take a screen capture, and then i combine it with the breadboard footage.
To make a 3db/oct slope.
- Make a parallel section: one side with the unfiltered noise signal, one side with the 6db/oct slope filter
- Invert the phase of the filtered signal, and reduce the amplitude by whatever factor is equivalent to 6 decibels of perceived loudness (possibly 50%?)
- Recombine the signals, and you'll have a 3db/oct slope filter.
Thats how i would do it in my DAW if i needed to make a 3db/oct filter and only had access to a 6db filter.
It'd be the same as routing the audio from a parent track to a parallel send track, putting a 6db/oct filter on the send, inverting the phase and lowering the output by 6 decibels.
:D
Thank you very much, Moritz, thanks to your Channel i started creating my modular synth:according your video and shemes already assembled and working 2 vco(first one is not so stable keeping octave, seems because of component) second vco is stable tested with external midi keyboard +doepfer midi to cv or with korg sequenser with cv/gate out, also assembled VCA, ad/sr, and most Hard for me - ladder FILTER, all works good, some moments out of range - but it is because of components i used.
Are all the resistors 1/2 watt? If not what voltage are they
I love these videos and they are always super high quality and easy to understand. The explanations really do showcase the fundamentals of audio circuits!
I wonder if you could improve your top-down shots with a Telecentric Lens? It would remove the perspective distortion on your breadboard, allowing the viewer to see the circuit in "2d", orthogonal view. So the resistors and cap leads aren't out of place. I suppose you could get the same effect much more cheaply with a telephoto lens placed far away, at a high zoom...
Usually, white noise is noise containing random frequencies with equal energy per frequency, whereas pink noise is noise containing random frequencies with equal energy per octave, so, pink noise tends to sound like it has more bass frequencies in it than white noise does, blue noise basically contains random high frequencies in it, red noise contains random low frequencies in it, there's also brown noise, or Brownian noise too.
These videos are really great Moritz, but one thing that's missing (unless I missed it) is what kind of output module we need to connect our audio to an amp, headphones, or computer's audio in without blowing anything up. Some YT videos just say "don't worry, connect it up", but having 10V p-p signals going into a laptop or audio amp sounds like it might do some damage....?
PS: A red wire connecting to ground on the breadboard? I thought you were better than that.... ;)
you can use something like this to scale 10 V pp signals down to consumer audio line level: tinyurl.com/29kcbouk
@@MoritzKlein0 Great and INTERACTIVE answer, very cool - thanks! I finally signed up for your Patreon. :)
astonishing quality moritz! Thank you for all the top tier content.
The classic way noise is generated in a Synthesizer is by the use of a reverse-biased Diode junction, or a reversed-biased transistor B-E junction, you do have to hand-select a diode or transistor to find one that generates a good amount of noise though.
I had never heard of blue noise before. I have also heard some other "colors" mentioned, but have no idea what their specifics are.
Some years back, I built a device that used a 12 volt power supply and utilized the base-emitter reverse breakdown mode as noise sources. At that time I had those transistors in sockets, with the thought of selecting them for maximum noise output. This was probably not a good idea, as Ive since learned that subjecting a transistor to that kind of reverse breakdown has a permanent and adverse effect on the transistor's beta.
Did you select a particular kind of transistor as being optimum for this application or did you just use whatever you had on hand?
oh interesting. so the transistors get "worn down" by producing noise? i wonder if they'll fail over time. in my case, i tried both the 2N3904 and the BC548. the former's output is super quiet, while the latter reliably gives you really strong noise. so i kept using the BC548 for noise purposes going forward, and it hasn't failed me so far!
@@MoritzKlein0 Not "worn down", just that running them in base-emitter reverse breakdown does something irreversible to them, I am not clear as to the details of it.
Hello mister Moritz Klein,
WOW, so many smart explaining and analogies in this video, I learned so much from only two of your video's... Amazing.
Great explanation and instructions and the video's themselves (the production) is exceptional, you earned yourself another subscriber !!
Thanks for making this! I'm curious - does abusing the transistor like this shorten its lifespan at all?
Not if you keep the current low. Moritz is using a 100k resistor here, which will only let about 50-60 uA flow.
exactly - should’ve mentioned this in the video!
Is it possible to miniaturize this (white only) to fit into an earbud (as an outside noise masking for sleeping)?
yeah, if you go SMT!
@@MoritzKlein0 Is there a site/service where I could upload the schematics and they'd produce the entire devices with SMT components, not just the board?
Heh, the sine in your drawing is what we used to call a nine wave in college.
*Nearly* a sine wave 😉
i was debating wether or not i should re-do it, but i realized that the next attempt wouldn't have been better necessarily
@@MoritzKlein0 you should see mine ...
I've used all your components and have used the exact breadboard layout for the white noise circuit. I get white noise but it's very quiet. I'm using an 8ohm speaker for my output. Any suggestions on how to make this much loider
Could I skip the amplifier step and just use a pedal with any sort of boost? (boost, distortion, etc)
if they‘re input buffered, yes!
@@MoritzKlein0 i...think so? Pedals that ARENT true bypass are buffered aren't they?
@@MoritzKlein0 also curious what the 100k resistor is doing, maybe i misunderstood that part of the video. what would happen if its a different value? or there was no resistor at all? im trying to put together a white noise circuit of my own, but i have a different transistor on hand so im curious what part it plays.
woo, been looking forward to this one!
Nice! Will be looking forward to the sawtooth to triangle video. I have built your oscillator with the old saw to triangle converter, but it kinda has some high frequency content due to the transition between up and down not being perfect
i found a fix for that in a previous livestream - will work it into the new design.
@@MoritzKlein0 awsome!
so in depth!
Hm, the avalanche breakdown noise is in fact shot noise with a certain characteristic. The charge carriers have to overcome a certain potential barrier to initiate a cascade of secondary charge carrieres. This means, shot noise is allready "coloured". I prefer thermal noise (of a metall film resistor or a low power light bulb) as source for a white noise generator, because this is real white noise with an even frequency distribution.
Can you do 3db slopes by summing 6db filter with original signal and then dividing by 2 via op amps?
Hey Moritz, with Conrad closing down, where will you get parts and tools and enclosures and stuff?
i usually go to a small store called “segor electronics” here in berlin. can recommend!
Nice that exactly what I looked for actually exists
Amazing video as always! Would love to see this noise hooked to a quantizer and generating random melodies.
You need also S&H for this.
i really want to revisit quantizing once the erica synths collaboration is through!
@@mpingo91 luckily, if i remember correctly, moritz already did a video on a s&h.
Fantastic video as always Moritz, thank you so much for your efforts. Excellent explanations and demonstrations.
thanks, james!
Great video, thanks. Is the junction breakdown really a white noise source, how do we know it isn't coloured already (by the physics of electrons etc)? A pseudo-random generator such as a 32-bit binary shift register with XOR gates could be another way to generate an effective large-amplitude audio white noise source.
6:41 On the breadboard the emitter is now connected to ground through the 100k resister and the gray wire. I'm a bit confused. Very informative video nontheless!
yeah i messed up there. should‘ve gone into to positive rail!
@@MoritzKlein0 Haha at 16:05 I see the correction 😅 Thanks for the great video!
Would another way to get a 3dB/oct filter be to have a 6db low pass signal mixed with the dry signal? Could that cause phasing issues?
Great video! As all your previous, love them! Just wondering, the "white noise" inputs to pink and blue, are they directly connected to the white output or through a buffer? My feel from the video is that there is no buffer in between, just straight on from the white output?
yeah, since both filters have a pretty high input impedance, i don’t think an additional buffer is necessary.
Hi, nice series. Can I connect to output next OP as headphones amp or output is to high (+-10V)? Thank you.
I've been playing around with this circuit for a couple of days. I am using a 2N3904 transistor so it "could" be different from the BC548 or others.
I needed a lot more gain in the white noise to get good enough levels. I added a second gain stage with a voltage gain of 32 to get close to what I expected (about 7.5V peak).
The GBW of the transistor is 3 MHz. The gain in the White noise part of the video is set to 148 (100K feedback, 680 to GND. With the 3 MHz GBW, that would be a bandwidth of 22 KHz. Seems OK for Audio.
However, with a gain of 148, and an offset voltage of, say 3 mV, is a DC offset in the output of around 0.5V, which is what I measured. I tried a TL084 with slightly better results. I ended up adding an additional 100 ohms to ground (dropped the 680 to 560) and a 50K trim pot with 220K to the wiper (the classic circuit for trimming out offset errors). This was enough to easily trim out the offset voltage error.
Using the White output to drive the unity gain of the Blue output didn't have enough amplitude. For that I changed the unity gain buffer to a gain of about 3 (24K feedback, 12K to ground), That was about right.
The pink level was WAY too low. I added amplification there as well. Something around 16x was too much (100K/6.8K). I'll probably raise the resistor to ground to 10K and call it good.
All of this to ask this question - I expected that the RC values in the Pink noise circuit would be somewhere near the corner frequencies but they are WAY off what I expected. For instance, R=2000 and C=330pF is up around 1.5MHz. The other end R=51K, C=33nF is at 594 Hz.
What am I missing here?
I ran an LTSpice simulation and the Pink circuit works just as described in the video.
I re-did the RC calculations adding in the 100K and got something like the video (corners at 200Hz, 2.7KHz, and 29KHz.) Perhaps that 'sthe right way for me to see the "why" this circuit works.
unfortunately, the 2N3904 produces barely any noise. i've run into the same issue. if you switch it for a BC548/547, you should get much better results.
@@MoritzKlein0 That makes sense. It's not the typical transistor here in the US, but I'll add some to my Mouser cart for next order.
i‘m not sure this covers your other concerns, though
@@MoritzKlein0 It might because the noise itself might be better.
After noise comes S&H, usually. PS, nicely explained
He’s already done a s&h video
ruclips.net/video/kIJqzkRe4do/видео.html
Can all 3 noise sources be built into one module by combining their filter inputs after the first buffer and using a switch to select the outputs? It seems like the filters might interact.
Excellently explained! I have never seen this made so clear. Thanks!
Ive made this circuit with correct values, white is working well and is stable, pink works but after about 15seconds it starts breaking down into a crackle, dropping from 4v peak to peak to 0v. I didn’t have foil caps for the filter, so I used 2 film caps and a ceramic… could this be the problem? Turning the power off and back on brings the pink noise back but it only lasts a few seconds.
Worked it out… it was a faulty TL072 or bad connection on the opamp. Changed it and it’s works fine now
Looks like
red wire is +12v
Green wire is -12v
And black clip is ground (white wire)
Can this work with 9v? I need to change components?
I love this, do you know how to make a sample and hold circuit for this? I'm trying to sample to a capacitor, but it loose it's charge quite fast 😅
why do you connect your emitter to the ground but say it's the supply voltage? This circuit is confusing me.
The emitter is not connected to ground. The triangle pointing upwards is often used as the symbol for Vcc. Generally, ground is indicated by a triangle pointing downwards. Or, as in this video, ground is represented by three stacked horizontal lines.
I've tried to simulate the white noise circuit on TINA TI and i cant get the same response that you seen on the osciloscope, can you help me with that. I am trying to build and white noise generator to simulate the response of a Sallen-Key low pass filter.
I think you need and extra stage in your blue noise filter system to extend the high end to 20kHz.
Great work as always amigo
And now I finally understood what noise is! Thanks so much!
I loved the video, but have a question. You said the high pass filter had a cutoff of 1.6hz. I've been working on a random LFO that outputs voltage from 0v to 3.3v (arduino based) and I would like to shift it so it is centered on 0 volts. Could the capacitor/resistor be changed to allow much longer periods in the + or -, like 20-30s? I'm guessing not, but I'm a noob when it comes to designing circuits.
Or could the arduino be run at 1.65+ as the positive and -1.65v at the ground?
yes sure, that'll work. just use a bigger resistor or capacitor. you can calculate the cutoff frequencies of different r/c combinations with this tool: sim.okawa-denshi.jp/en/CRtool.php
Hallo Moritz. Is it possible to obtain a blue noise output, by feeding + an - opamp inputs with white and pink noise respectively, in a differenciator configuration ? Just an idea to save some components. And what would be the result with pink and blue ? White output again ? Thank you.
The fourier transform is linear, so I would expect subtracting pink from white to work if the amplitudes match up. Not sure how it would work out in practice though with the filtering involved etc
Pink noise should be enough to make blue noise, and vice versa:
-3 dB/octave is hard and 3 dB/octave is also hard, but if you have one then you should be able to get the other using simple filtering.
So at least in theory, if you pass the pink noise through a 6 dB/octave high pass filter (differentiator), then you should get blue noise.
And if you pass blue noise through a 6 dB/octave low pass filter (integrator), you should get pink noise.
It doesn't have to be a perfect integrator/differentiator, just act more or less like it over the frequency range that you care about.
In practice, you might get some trouble because some parts of the input signal are quite weak, and those are the ones that you would be amplifying the most, but I think it could work.
Wow, you explained this so well! Thanks for sharing, very informative.
Excellent video!
Curious what a band pass filter in here would look like!
Good idea. There's still an unused opamp on the chip.
@@RayMcNamaraMusic Yes! But the more I thought about it.... wouldn't you need two more op amps? When I picture it in my head I'm visualizing basically building everything in the video again.
@@mathieumartin9344 You don't have to build the whole thing in duplicate just for another filter type. You could use the same white noise source and send it to the BP filter, which is basically a LP and HP in series. You could pull that off with a single opamp.
Awesome 👏🏻 as usual !
Nicely done!
amplifying the BJT signal is a form of coloring the noise because the op-amp is bandlimited
Thank you Mortiz😁✌️
Hi, Is j112 can be used if no j113?
For sample&hold sheme
yup, no problem!
Awesome, Moritz!! Thank you!
Moritz, what type of capacitor do you use and are they better suited for the purpose of audio?
I would like to see a brown noise circuit *and* a circuit that will give an animated sweeping effect with variable rate. As well as a gated input. *Please.*
You can try to use any type on non polarised capacitors(so electrolytic and tantalum don’t work) for audio, even the cheap ceramic ones in most cases. The one he uses are called film capacitors or foil capacitors, they are meant to be better for audio but are also significantly more expensive. It maybe worth trying to use the ceramic ones on a breadboard or something, if the circuit sounds fine you can save some money
Also for brown noise, it’s just a simple 6db/oct filter of white noise en.m.wikipedia.org/wiki/Brownian_noise .
so. A simple 1pole passive low pass filter with 1 resistor and 1 capacitor will work
@@woosix7735 the main downside of ceramic capacitors is that they are microphonic.
The really cheap ones have terrible tolerance, temperature coefficient, and voltage coefficient too.
Great videos. How do you get your voice-over sounding so slick? A good mic with a compressor?
Creative video, thanks :)
So interesting ! Maybe we are ready for an analog drum machine ;)
definitely on my list!
Twin T's are probably a really great place to start, combined with the blue"ish" noise, you are on the way to old school transistor rhythm machines. I wish the days of old with electronic magazines "build your own rhythm box" were still commonplace. While they were still published when I was really young, by the time my teens rolled around, It was the sparse articles in electronic musician (diy level converters and the like)
I would like to see a 7/15 bit LFSR digital noise generator. I tried with what i had, a 74HC595, it didnt work well, using external clocks would make the chips unpredictable. Im gunna try again with a CD4094
15 bits is probably too small and the pseudorandom pattern will repeat every second for a 32KHz clock. Use a 32bit LSFR or bigger for a more random output. This is even easier with a small micro and a bit of code.
@@mustang2440 I see 32bit too big for audio purpose, yes it can give a cleaner sounding "white" noise with more randomness, but I mostly care about the harsh digital noise. I'm using 15bit because its only 2 chips and flipping a switch turns it into a 7bit for harsher metallic sound. the usually clock I use ranges from 0.1Hz to 10kHz so the repetition is minutes to seconds and with modulation that's even less noticeable. I have the schematic if your interested
@@leomorev8912ok yes makes sense for a harsher sound but any clock below 20Hz you won't hear as sound, but as clicks.
great. before this I knew only how to design punk noise
I wonder how the noise colors were decided.
white noise is an analogy to white light. in white light, every wavelengthe(frequency) is present with the same amplitude. with white noise, all the frequencys are also present with equal amplitude. for the other colours of noise dont realy have an optical analogue, but blue light is higher frequency and red light is lower frequency, so kinda similar to noise colours.
Love it
is the 12v ac or dc?
it’s dc.
@@MoritzKlein0 awesome thank you
Hey Moritz :)
Thanks you soo much for your awsome and also inspiring videos. I'm fully pumped building my own stuff along with your vids.
One thing that is rather confusing for me though is, ordering all the components. I mean, i know how placing internet orders work :D but I mean, do you buy your components normally in bundles? What sources can you recommend (in germany / austria) and what kind of kit (like resistors, capacitors, potis, diodes etc.) would you recommend for a beginner like me?
Thx in advance
the white noise is the same noise than a television whitout antenna , and looking at osciloscope, the white noise rises amplitude in high frequencies, and pink noise has all frequencies at same level ...
When I listen to white pink and blue noise... 🏳⚧
The shelf filter is a really cool concept that I’d never really heard of, and it was really well-explained. But why can’t you just mix the original input (the white noise) with the 6db/oct filtered output so it’s like only 50% filtered, 50% dry signal? Wouldn’t that be an easier way to get 3db/oct, hardware-wise?
Exactly my thoughts, then with a few pots you could vary from -6dB HP to -6 dB LP, sweeping through blue and pink spectra and getting a BP filter too. I imagine you don't have to worry about phase issues at all since we're just mixing noise.
That's basically what a single shelf filter is doing. But on its own, it's not very close to the 3db/oct curve, hence stacking them.
aww man, this doesn't work very well with 9v batteries, just tried it, it needs the 12V.
Edit: you can hack it to work by connecting the base of the transistor(middle pin) to the negative supply insted of groud. It jusses the transister up with 18V insted of 9V
oh good to know! have you also tried using a weaker resistor between the supply voltage and emitter?
@@MoritzKlein0 no I havent tried that. thinking about this probably every transistor is going to have different brekdown voltage and noise volume charecteristics, because it's not an intended use and is not spesified by the manufacurer. you just have to try a bunch of stuff untill it works i guess
How about red or infrared noise, especially as connected to a Sample/Hold?
I think a S&H is one of the modules that's promised to be coming up in the series?
I hopped for an introduction to DSP theory
ruclips.net/video/0yB_h_wFkh4/видео.html - Why was that transistor connected to the ground from 2 sides?
And better question: Why was it still working?
good question! because i started recording video and audio separately, and i messed up here. (the audio take is from
a working version of the circuit setup.)
Brown noise? 😃
If you substract pink from white, you get blue
I don't quite understand the color choices for these noises 🤣
afaik those are just the result of a mapping between the audio and light spectrums
I've just made the white noise schematic with tl072 op-amp but no noise output. I'm getting 11.3volts at the output but no audible noise. Any suggestions, anyone?
The schematic visible at 8 minutes
Hi! Greetings from BR :))) 🇧🇷
Please, put "making white noise" on this video tags for more people then me discovery this content
I am not very impressed, I am a chartered electronic engineer and this is mainly unguided and misleading.
Voltage does not push current through, current is drawn by a load, voltage is like a bucket of energy. Energy takes the path of least resistance in electronics, as in all areas of life, so flows into the load based on the load.
The breakdown you are witnessing is not some cruel effect, it is called the zener effect and this phenomena is a fundamental building block of electronics and has been for nearly 100 years. Providing the series resistor limits the current then the reverse voltage semiconductor will stay in those conditions indefinitely.
Transistors do not give white noise, low frequency is made up of flicker noise and higher frequency is thermal noise (thermal noise is very close to white noise). You can tell by looking at your oscilloscope waveform the noise is not white (as it is not equally distrubited positive and negative around 0V)... It sounds grainy in comparison.
Opamps must ALWAYS have a decoupling capacitor for operational stability and for rejecting unwanted pickup from the external fields all around.
Breadboard is not good for prototyping analogue electronics, or digital electronics. They look nice though, and they are fun to poke things into.
According to the maths your 100k/33nF filter only gives 26dB of rejection at 1kHz, so the output will not be flat, there will be a 1kHz component at around 1/20th of the input signal size (20dB +6dB is equivalent to X10 X2). With 1kHz and 100k/33nF the output waveform will be a triangle wave, but this is only based on the relationship between the 48Hz f-3 of the filter and the signal frequency. If the signal frequency is changed then the waveform shape will change.
There is an IEC standard filter for generating pink noise, I don't know why you would want it unless you are soak testing/running in loudspeakers you are selling. What is your purpose for making a pink noise generator?
Ading a 10k resistor as a zero (shelf) into the response does not give a square wave output, it gives a distorted sawtooth that is around twice the peak voltage of the previous circuit. This is also not just a potential divider, there is an RC which represents a time constant (charge time) and a filter with a complex mathematical pole zero equation that allows us to model gain and phase vs frequency.
It seems you are not educated or experienced, I don't understand why you would want to teach or sell designs based on this.
who is that of blue pink and white 🏳️⚧️?? aca se dice celeste blanco amarillo 🇦🇷🇦🇷🇦🇷🇦🇷
Dude became German at 3:35
🤍
I could have sworn the next video would be about subtractive synthesis my bad
I need brown noise generator.