World's easiest oscillator! Introducing the CD40106

hi I'm King cos and I'm a synth DIY guy and today we're gonna do something real fun go back to the breadboard I have here my trusty Heathkit electronic design experimenter which surprisingly despite the fact that is probably as old as I am it works I hadn't actually used it a student bought it for me at a flea market and I hadn't really tried it and it works the power supply I've dialed it to be about 10 volts positive and negative although for this circuit we're only gonna use positive so what are we doing here today well we're taking a look at the magical I see a magical integrated circuit called the CD 4106 CD 4106 it's known as a hex inverter which basically is six Schmitt triggers now this is a very common dip package let's put a little bite here so we know that this is pin number one and it's got 14 pins so that means seven pins on each side right I usually draw it like this one on each end one in the middle and then add two in between then you have your 1 2 3 4 5 6 7 right so this is 1 2 3 4 5 6 7 right here goes around 2 8 9 10 11 12 13 14 and says pin 14 over here now 14 is where you apply positive voltage right here in seven is where you apply zero volts also known as GND or ground so this is how you power this is what it looks like even though we're gonna use it for some interesting noise making synthesizer circuits it is not required to use eurorack type power we're not gonna use positive 12 and minus 12 volts we're gonna use zero and something like nine volts so you could actually power this from a single 9-volt battery which is pretty handy if you're making something portable noise maker that you can take with you I've done a lot of projects using this chip I've led workshops with designs that I've created using the 4106 hex inverter chip and why is it so fun why is it so ubiquitous in beginner DIY endeavors because I can claim without being afraid to be wrong that this is the simplest oscillator that you can make well will it tune to 1 volt per octave it you can use to make Bach music probably not but it's an oscillator nonetheless and one that only requires three components basically three components so apart from these two pins which are power pins all of the other ones while the other pairs are inverters the way you draw in inverters like this little triangle now don't get it confused with an op-amp okay it's a triangle but it only has one input and one output whereas an op-amp symbol will have two inputs one inverting and one non-inverting input right you have these little triangles and notice that they're always facing the same direction if you have your pin one here on your left every inverter triangles facing towards the right and this is what they look like the inverters symbol itself will have a little little thing like this we dot the output right there now how do I make an oscillator with one of these inverters well here's the input here's the output it's as simple as a capacitor to ground and a resistor from input to output and voila that's an oscillator really that's it it's that easy you take a capacitor to ground from the input and you tie input to output via a resistor let's call it R 1 and C 1 and here you will get a square wave output right there how do you adjust the frequency well the frequency is a function between capacitor and the resistor basically what's happening is this is an inverter right so let's say that this output is high when the capacitor is loaded it'll let the current through and this would be high so this will invert and goal though which will make the capacitor discharge when the capacitor discharges you get low here which makes the inverter go back high and so on so forth generating an oscillation and of course the speed of oscillation will depend on how much current the capacitor can hold so how high a value capacitor you're using and how much current is detained by the resistor so the higher the capacitor and the higher the resistor the slower the frequency so here's a few things that one should know about the hex inverter first of all they're sensitive to ESD so it's very important when you're handling these guys as most CMOS chips are very sensitive to ESD which is electrostatic discharge that means static electricity from your hands right so if you're walking around on a dry rug you might accumulate some energy that you know discharged when you touch the chip and it's very easy to burn these guys so I use in ESD bracelet to avoid that with the other end grounded somewhere where you know will discharge any static energy that you may be accumulating the other thing is it only takes from 5 to 15 volts if you under power it you'll starve it which can be cool you can get some cool results that way but if you over power it you might burn it ok now ground and you used inputs if you have a floating input it might just start oscillating on its own so it's probably a good idea to ground any inputs that you're not using and again the inputs are the pins one three five thirteen eleven and nine if you're using the chip for less than six oscillators you should ground the unused inputs another thing that you should know about this chip is its putting out a square wave out of the output here when you have the circuit set to oscillate which again is as simple as a resistor tying input to output in a capacitor to ground but out of the input here you have a triangle oeid wave sort of a triangular wave and I'll show you in a second the thing is though this square wave is nice and strong it doesn't need any buffering however this triangle wave over here is weak so this means if you want to use the triangle wave as a signal from your 4106 oscillator you need to buffer it so make sure to buffer it and I will refer you to my video on the dead bug buffer so I don't waste time here explaining whatever I'd explained before so if you want to know how to make a buffer using an op-amp it's very easy you can go check out either my op-amp video or my dead bug buffer video for that now what kind of fun things can you do with this thing well one of them is you can set up an oscillator and you can use different kinds of resistors to vary its frequency it's harder to find variable capacitors so you can just keep the capacitor value but you can use all sorts of different resistors for this feedback here here's another thing that you should keep in mind with this chip you don't want to short the input to the output so if you're gonna use variable resistors that may go to zero ohms then you should definitely use at least a hundred ohm resistor here in series with any other resistors you may use so that if they hit zero ohms you still have a little bit of resistance here between the input and the output it's just good practice to do so now I can use a potentiometer for example and the way that I will use the potentiometer is as a variable resistor not a voltage divider meaning I will not use one of the terminals one of the extremities I will simply use one extremity and the wiper and that will give me let's say 100k that will give me between 0 and 100 K ohms resistance between this point right here and this point right here okay and that is one really cool way to vary the frequency of my 4106 oscillator now another thing that I can do is use a [Music] LDR right which is usually this symbol right here an LDR is light dependent resistor so that means that it will vary its resistance according to how much light is hitting the sensor now here are some kinds of variable resistors I can use a ribbon like a soft pot which is a position based resistor I can use an LDR which is light dependent I can use a potentiometer and just a regular resistor and any other kind of variable resistors you can think of can be used as well so I've gone and done just this over here on my breadboard I did more than two oscillators here so these are the schematics of the main oscillator that I've done right over here so that there's the the chip right there 4106 and i'm using the power supply from my Heathkit although I've dialed it down to ten volts instead of 15 and right here in the board the first thing you notice is that big capacitor there I put it there to smoothen out the power there's also a jack that's connected to my more tax data oscilloscope and from there it's going into my audio system so that we can hear what's happening here and now right there on the first pin 1 & 2 you see that green cable and the blue cable coming out the green cable is going over there to where I have two cables connecting to that 100k on the geometers right on my Heathkit and that's coming back through the LDR right there which is a light dependent resistor and then that blue little blue cable at the end of the LDR is going back into the output of that first inverter which is made up of pins 1 & 2 on my 4106 chip you also have this capacitor right here which is a 1 micro farad capacitor one end of it is jumped to ground right which is pin 7 on the chip is grounded I'm using that same row for grounding the capacitor and the other leg of the capacitor takes that little red cable right there to the input to pin one of the 4106 so that's exactly what's happening over here right so we're using pins 1 & 2 of the hex inverter chip now let's listen to it and look at it right as I turn up the volume here on my little amp start seeing that square wave and we start hearing as well and here since I've put the LDR in series with the potentiometer both of them affect the frequency as I turn it down you go down load down to actually clicking which is like Ella phone rings right like earlier I was getting higher pitch because there was more light but I can still buy approximate in my hand make that oscillator go faster or slower see now that in itself is pretty cool it's what's commonly referred to as a light theremin usually when you see the iy projects called the DIY theremin is probably something like this a 4106 oscillator that is controlled with an LDR okay now I've made a second oscillator here pins eight and nine of the hex inverter this one actually has another capacitor here it's a 10 micro farad capacitor so it's 10 times the value of this one so right then we know this the frequency is going to be a lot lower so this one is meant to be an LFO and it goes through this 100 K potentiometer that I stuck right on the board here basically the output is lighting this LED right here so as you can see it's so slow that it's like a slow blink definitely wouldn't hear that as an audio frequency at all and as I turn this this potentiometer here it gets faster and faster and faster see up to where you just see the LED constantly lit because there's blinking so fast that you can't really tell now what's cool about that is that I can then turn this led to face the LDR right of the other oscillator which is pretty much a homemade vector all right and now as I turn my volume back up and we listen to that first oscillator again so let's turn this so it's oughta buggin and there you go a voltage that I'm generating with this oscillator here is lighting the LED which in turn is affecting [Music] the resistance and therefore the frequency of my audio oscillator so basically I've created an LFO so let's turn that frequency up there you go now we're a family at first isolated right there and I can still affect it unless I were to encapsulate that led and ldr combo I can still use my hand to put a shadow over the whole assembly and now I'm affecting the frequency with both my hand [Music] and the LFO right there in the LFO is simply being controlled by this variable resistance here which is my potentiometer now all I'm dealing with right now are square waves because those are the ones that come out nice and strong from the 4106 inverters but I could also use a triangle wave so all I need to do right now [Music] let's take this little red cable here and change it to the input that's what that looks like it's more like a shark fin kind of a shape [Music] and it sounds much softer of course because it has much fewer harmonics but it'll get loaded down easily depending on where you plug it into if it's not a high impedance input it'll get loaded down you lose signal so make sure that if you want to use the triangle wave from one of these oscillators that you do use a buffer for it and that's it that's a little breadboard circuit here using my heat kit electronic design experiment or board I have only used two of these six potential oscillators in this single chip so one fun thing to do is to make a little module where you have Center ometer control over six of these oscillators and you can have them interact in different ways you can use diodes and make them hard sync each other there's a lot you can do with these and maybe I'll do another more advanced lesson about them but for now this is it I just missed making you know these fun little videos with things that you can pull out of your drawer and have fun with and not just kit reviews and this is one of the funnest things that you can do with since DIY when you're beginning is to just make oscillators with the 4106 Schmitt trigger inverters I hope this inspires you to have a little fun with a breadboard again and if so hit like subscribe leave a comment hit the bell join my patreon and that's it see you soon and stay noisy [Music] you [Music]

Channel: Synth Diy Guy

Views: 32,872

Rating: 4.9515805 out of 5

Keywords: Quincas Moreira, Hex Inverter, cd40106, Schmitt Trigger, Oscillator, VCO, LFO, Vactrol, Triangle Wave, Square Wave, Logic, Synthesizer, Modular, Eurorack, Synth DIY, SDIY

Id: P4SwaI09Zxc

Length: 17min 53sec (1073 seconds)

Published: Tue Oct 01 2019