Casper Electronics DIY synth building. Part 1: Oscillators

in this video I'm going to talk about oscillators what they are how they work and most importantly how to build your own so we're going to cover a whole bunch of stuff from building making a regular soda like this you can see in the scope here two square wave and then we're going to look at a bunch of ways to control the oscillator so okay or with this is using graphite you can draw a piece of paper and then the resistance of the graphite will allow you to change the pitch of the oscillator we're also going to do light control and then you can do things like use your phone or anything that makes white and you can chain with the pitch and then we're going to go further I'm going to talk about creating stepped tone generators so that's where you can hear the it's jumping up one note at a time we are actually getting a harmonic scale and then you can use that with with your other types of control so you can get sort of melodic scales I find this is really useful to turn sort of noisy sounds into more melodic sounds and then we're gonna go a bit further and talk about different kinds of modulation and in the following videos I'm going to talk a whole lot more about this but in this video the first thing we're talking about is really just how to make our core sound generator before we start looking at how to make patterns and how to make music and how to make more complex sounds we just need to make our our sound generator our core block and then we'll be able to get into this so the first thing I'm going to do is I'm going to show you the materials we're going to use the electrical components the tools and this thing right here this is the home synth mini lab this is a project I'm working on for a little while and it's basically just a prototyping interface well it's prototyping and performance so this is where I build circuits and then this is where I'm actually able to play them as well so there's a variety of switches potentiometers these are more switches touch pads all different things that you can put into the breadboard so that you can build the circuit and then actually play it and what this has is at the top we have our power supply we have a speaker and an amplifier a mixer a bunch of input and output jacks for connecting to other equipment and then a bunch of controls here some buttons and potentiometers and some lights so that we can quickly build circuits and test them out so let's get started I'm going to show you first the tools we're going to use then the materials and then we'll start building some circuits so you're going to need some wire strippers and some tweezers you'll need a breadboard and in this case I'm using an oscilloscope but you really don't need that as far as the material we're going to use you're going to need some wire I like two or a bunch of different colors and then these are these like jumper wires I ordered a bunch of these on eBay and for electrical components we're going to use resistors some capacitors and some integrated circuits and I've tried to keep this as simple as possible so I'm just using sort of the most common values so for the resistors I'm using one K 10 K 47 K 100 K and 1 M and for the capacitors I'm using 0.01 micro farad 0.1 110 and 100 and for this video the IC we're going to use is the CD 4106 so it's sort of one of the most common experimenters onto graded circuits so first we're going to talk just a little bit about what this chip is so this is a 14 panda chip and it's a hex MIT trigger I'm not really going to explain what a lot of this stuff is if you're curious there's lots and lots of resources that are better than I can explain it but I'll just show you really quickly so this is a basically a hex inverter it's a logic chip and it's got six of these little independent and burgers in it and you power it here that's where you apply power this can take anywhere between 3 and 18 volts we're going to be running it on nine and then we're going to use these individual inverters to make oscillators and what's really cool about this chip is that every single one of these can be an oscillator so we can make six oscillators with this chip the pins are numbered like this okay so I'm going to start by making an oscillator and then I'll show you schematic and explain a little bit about how it works so first we're going to put the chip in the board we're going to run power to pin 14 so that's going to be a little jumper here to the positive bus that's the red line here and another wire to the negative bus or the ground there then we just need two more components so we're going to take a 1 micro farad capacitor and plug that into pin 1 to ground and then we're going to use a 1 ohm or sorry 1000 ohm resistor between pins 1 and 2 and then I'm going to plug that into my mixer which on the ohm scent is right here so here's the square wave which you can see here we can also get a triangle wave which we can look at there it's much quieter but it's a triangle wave and if we want to make another one we just need two more components another capacitor and another a resistor and if we listen to that we've got another oscillator this one much lower pitch okay so but there's very few situations where we're going to want just a static like that so the first thing we're going to do is make this so it's a variable pitch and we're going to do that using a potentiometer so this is a variable resistor so I'm going to plug that in here between pins 1 and 2 and then I'm going to plug in to my amp and look at it on the scope again and now we've got our variable pitch okay so now I'll explain to you how this works and then we're going to build a whole bunch more oscillators so we've got our chip here we've got our little inverters they're actually Schmitt triggers which you have to draw this little thing there but so let's zoom in a little bit and I'll show you the schematic and tell you a little bit I'm not going to get deep into the physics of this doesn't really fit in the scope of this video and there's again there's a lot of other people that can explain it a lot better than I can but but just to give you an idea of how this works and at least to show you what are the things that we want to look at as we're experimenting so as I said before we've got three things three components that make this oscillator one is this Schmitt trigger this logic inverter one is a capacitor here connected to ground and there's a resistor that goes from the input of the inverter to the output and in this case we'll say it spins 1 & 2 of this chip here so what determines the pitch is the relationship of the resistor to the capacitor and we can change either of these to change the pitch so for an audio oscillator I'm probably going to use like a 1 micro farad but for a Sawbuck audio oscillator I'm going to use a 10 micro farad so that's a 10 times bigger capacitor and for a really slow collaterally use 100 micro farad so by increasing the size of the capacitor I'm lowering the pitch and the same thing goes for the resistor when I increase the size of this resistor then it will lower the pitch so I just drew the arrow there which means this is a potentiometer it's a variable resistor so it means I can change the resistance which changes the pitch now what happens to put it super briefly is that this is a device that looks at the input and that affects the output so when the input is high so let's say it's at 9 volts then the output is going to be low and what happens is this capacitor fills with charge and when it's full that's nine volts and then this is the so the charge starts to leave and it actually goes through this resistor and it empties until it becomes completely empty and now that represents zero volt this is not 100% accurate but for the sake of keeping it simple I'm going to keep it simple so once this is empty now this inverter looks at the input it says hey this is this is zero I'm going to be nine at the output now I'm going to go up to nine volts and what's going to happen then is that charge is going to go back the other direction it's going to fill up this capacitor and now this capacitor is gonna be full of charge and that's going to be like nine volts and the inverter will look at that and say hey that's a high voltage I'm going to go low now so then the charge is going to leave and it's going to go the other side and this will empty and it just keeps going back and forth and repeats forever that's your oscillation the rate that it does that is what makes your pitch we take this output we send it to an amplifier that goes to a speaker and then we hear sound so the takeaway from this though is that we're going to be playing with the value of the resistor and the value of the capacitor to determine how long it takes for this capacitor to fill so a bigger capacitor takes longer to fill and when it's full that represents a high voltage and this is low and again it goes back and forth so a smaller capacitor fills more quickly a smaller resistor will let more current through to fill up the capacitor more quickly so what we're going to do next is we're going to play with different types of resistors this is easy to do capacitors are a lot more difficult to play with that's harder to change so if I take this multimeter and I hold it in my hand there you can see that is 0.699 million mm so swell now it says 800,000 ohms if my hands are wet it's less resistance of the dry it's more resistance but we can also get resistance with graphite on a piece of paper that's another thing so if we put our mirror here we can see now we've got and it's moving around a lot looks like 40,000 if I move it farther away we're going to have more resistance so now it's 250,000 and the other thing we're going to play with is a light sensor so we've got this light sensor here and get the meter and we hold it up here and you can see that there's 1500 oops it's hard to hold okay so it changes with the light so now it's 5000 there's more light on it and it'll be 1,500 ohms so these are all things that we can change the resistance with we'll change the pitch so what we're going to do now is we're going to play with those different possibilities let's make a pretend a Seletar and we're going to listen to it here so again we've got our pitch there but now instead of a potentiometer let's use a light sensitive resistor here I'm changing the pitch ending on the light now this is a really common light dependent it's an LDR light dependent resistor and at full light it's about I think it's like 2 K and in complete darkness it's about 1 million ohms so that's a really good range we can get a really broad sweep with this device so then let's try another example so we're going to take so this is the input and the output of our inverter but again I should say the Schmitt trigger it's a special kind of inverter that I encourage you to look up and read all about and we're going to take some alligator clips here we're going to connect those to the input and output and now let's see touch them you can see it just going up and down okay but that lets you can see that range is not so great it's that's a little too low so how do we change the range well as I say before we can change the capacitor so I'm going to take out this 1 micro farad capacitor and now I'm going to put in a point 1 micro farad so let's plug that in so that's between the input and ground I'm putting this capacitor this is a point 1 now and turn the volume up and when I touch this it's going up now so we can try let's put that again to our paper and it's going up and down let's try another drawing so you can do a lot of different types of things maybe you want to make some sort of pattern and the more graphite there is the less resistance there will be so which I'll show you so and that goes down really fast but maybe I want at this point but as I put more graphite here and get the pitch will go up you so you can really tune it to be at different nodes if you want it to be different notes you can just sort of add more graphite until it gets out that you want so that jump is too big I'm going to add a little more there those are the two notes that I want and maybe there's a third but that'll be quite a drop okay so there's some of the basics of using different kinds of resistors and we can make all kinds of noise since light oscillators touch a sort of sorry like a light theremin to change the pitch touch controls to change pitch but now let's go further so what I find is that a lot of the time these oscillators I want to do something a bit more musical so I don't want to just make a bunch of random squealing tones so the next thing I want to show you is how to make a stepped oscillator and what that is is where I'm going to use one oscillator so I'm going to build another one this can be the same way where I've got my inverter this time I'm using the second one and between input and output and I have a resistor and at the base I don't have a capacitor but what I'm going to do is I'm going to take the output of that oscillator and I'm going to feed that into the input of another one like this and these are both variable okay and let's plug these two potentiometers and what's happening is I'm feeding I'm feeding one of these oscillators into the other one through a capacitor so as the current is going back and forth and it's doing that that bounce back and forth that makes our oscillator we're also getting a little bit of signal from this one it is sinking this oscillator to that one and rather than try to explain it I'll just play it for you so so you can hear hasn't changing the pitch of this oscillator it's jumping notes rather than doing a steady steady glide so here's the master oscillator and you can hear that one is smooth but the one that's being controlled is low and you can do a lot of cool stuff with this so I can change if I go to a lower pitch now I get this primal tune and if I go to a higher pitch I'm gonna get steps so now if i plug in my keyboard again and we can use a whole bunch of other things we could use use a light sensor so let's just clip the light sensor to the banana or to the how we do it so here you can see how light member slower our master oscillator speaking here are you gonna get nice little ones like a okay so now we've covered a bunch of different ways of changing the pitch and we've built a couple oscillators now next what I want to do is we're going to build another oscillator we're going to start playing with creating relationships between oscillators so we've already done that with the sync so that's where one of them is sinking the other but now we're going to make an LFO and that's going to modulate the pitch of one with a much lower oscillator so what I'm going to do is I'm going to take a large capacitor so I'm using a 10 microfarads and I'm going to build that I'm going to make that oscillator right here at the top so again with an our chip we've got inverter all along the top and bottom so I've used this one and this one now I'm going to use this one here I like to use the ones in the four corners because they're easier to get at the ones in the middle or a bit trickier so I'm going to take two more in my jumper wires and I put my capacitor in place then I'm going to put in a potentiometer so I can change the pitch of this and now I'm also going to introduce LEDs so what I'm going to do is I'm going to take the output of this and I'm going to take an LED and I connect that here and then through a 1k resistor I'm going to be able to look at the signal so there it is blinking you can see and the schematic for that here's my oscillator there's my capacitor to ground then I'm going through a 1k resistor so this is 1k this potentiometer is 100k I didn't see that before right now we're using a 10 microfarad this is my Schmitt trigger inverter and then we've got our LED well let's do it like this we've got our LED going to ground okay so and then you can see as I change the well and we don't call kitchen wear now we'll see as we change the frequency of the oscillator you can see the light blinking so one of them do is I'm going to take my oscillator here that's light cheerful and I'm going to hold it up to the light now that pits is a bit too hot so what I'm gonna do is I'm gonna leave that one that point 1 microfarad cap I'm going to put in one mega third set to town there we go lady see the pictures going up and down with the light amok so how to draw that Matic I would have my LDR here so that's and then I've got my inverter capped ground there's no LDR which goes between the input and the output and then that goes out to an amp to a speaker so this one is making light which is going to that sensor which is changing the pitch of this oscillator okay so now for the last part of this video we've got our oscillator we've played with sinking oscillators made a low frequency oscillator with a light now I'm going to show a way of connecting oscillators directly together so maybe we want to make a an LFO not using light we just want to plug one oscillator into the other so what we're going to do is we're going to make this is our low frequency oscillator so we're going to use a 10 micro farad cap then in the feedback loop we've got our 100k potentiometer and now we've got this is the oscillator we're listening to so this has a 1 micro farad cap so remember before I was saying 1 micro farad is generally in these applications for an audio oscillator this is for a sub audio then we've got again our 100k and this is going to go out to an amp and to a speaker we're going to listen to it and what we're going to do is we're going to run that through you can run it through a resistor a 10k but we want to make it a variable then this will be this will modulate the pitch of that well let's do that first so so I'm going to take the out to that one I'm going to run it through a 10k resistor so again this is our audio oscillator and we're going to add a 10k resistor to the input this is the capacitive ground and then I'm taking output of our other oscillator so let's listen to it and I'm gonna plug and then you can hear the pitch go so that's Oh and now what I can do is I'm going to take that and so that I can make it a variable LFO I'm going to plug it through a potentiometer so instead of just going straight in my wire is a little too short let's get another wire so now I'm going through this potentiometer and then to the input so there is relatively soft what I did is I still I left the limiting resistor in place so it can't get too low but if I remove that then I can just go straight and I can make it go so deep that it actually kills the oscillation so if you like squealy dying electronic sounds then this is for you so and then finally what I'll do is I'll take I'll put this capacitor from the output of my high frequency oscillator this is where things probably get a bit confusing I'll include schematics of all this if you look in the cup the description there are links to schematics where you can see what I'm doing but in any case I'm taking the output of my high frequency oscillator through a capacitor to the input so now we've got a step tone that's jumping up and down so that's the basic the basics of making oscillators there's tons of different designs there's so many so much better designs I didn't address these are current controlled oscillators there's voltage controlled oscillators which is sort of the backbone of analog synthesis but they use you know dozens of components or hundreds of components this uses three so I think this is as simple as it gets and this is really you know just meant to get you started and to really get you exploring and even with the most basic oscillators there's so much you can try so you know I encourage you to experiment with with light and with you know making these graphite scents with linking them all together and in the following videos after this I'm going to be showing a whole lot more about how they do sort of complex modulation making sequencers which I'll be showing you how to make next time which is not powered right now but this is an eight step sequencer that does all kinds of magic crazy stuff but there's a whole world of wonderful wacky stuff you can do and I'll demo a few of those now but won't really be explaining them but um yeah leave comments below if you have questions let me know um share your discoveries I don't know Oh you good you

Channel: casperelectronics synthesizers

Views: 263,623

Rating: 4.9664912 out of 5

Keywords: DIY electronics, Synthesizer (Musical Instrument), breadboard, OMSynth, casperelectronics, ljudmila, tutorial, DIY synthesizer, oscillators, schmitt tirgger, cd40106, light theremin, experimental synth, Noise Music (Musical Genre), VCO, atari punk, analog, analog synth, do it yourself, changing weathers, projekt atol, Electronics (Field Of Study), Electronic Oscillator, Synthesizer (album), Electronica (Musical Genre)

Id: FaoJaLmZaL4

Length: 30min 7sec (1807 seconds)

Published: Thu Nov 05 2015

Reddit Comments

[u/LastAveSF]

Check out ken stones mod source. He makes sq and tri waves from a 40106.

http://www.cgs.synth.net/modules/cgs21_super_psycho.html

I think this is what Casper has going on. Party.

[u/[deleted]]

Nice video. He showed, briefly, rearranging the circuit to get triangle wave output, but didn't explain. Any suggestion for further information on that?