Step 7: Make Weird Noises

This oscillator works with any standard 9Volt wall adapter, commonly used for guitar pedals, shown in the pictures below. Simply plug it in to the 9V jack, take a standard 1/4" cable, plug it in to some speakers, and you're ready to make weird noises!

You've now opened a can of worms as far as electronic projects go, as there are countless other synthesizer modules that can be built: filters, envelopes, more complex oscillator structures; the list goes on and on.

For some idea of what kind of sounds you can get out of this box, here's a video showing the unit in action:

<p>Hello everyone! I never anticipated this would become such a popular instructable! Because of its popularity, I'm going to be making some updates addressing the most common questions I've been asked.</p><p>First, I have uploaded a much nicer looking schematic, with more detailed notes on it. There is one embedded in the instructable as well as a pdf download for easier/more convenient reading.</p><p>Other planned updates:</p><p>-A fritzing diagram for the breadboard layout</p><p>-An eagle file so you can order a PCB custom made for this project!</p><p>-Information on how to get different frequency ranges</p><p>-A troubleshooting guide for some of the most common problems people have</p><p>If any of you have any suggestions for things you would like to see added/improved, please let me know!</p>
<p>Update #2!</p><p>I have just designed an eagle pcb for this, I've ordered a set and will confirm that it does what it's supposed to do, and then I'll post the eagle file, so everyone can have a nicely laid out PCB!</p>
<p>Hi, are you still working on this?</p><p>Nice synth by the way.</p>
If you mean &quot;where might parts 2, 3, etc. be?,&quot; I fully intend to [eventually] make some more instructables, but have never gotten around to it. This particular instructable I don't do much work on other than replying to comments and the occasional update.<br><br>Glad you like the project!
<p>Got it. I'm looking forward to your future 'ibles.</p>
<p>is there anyway i can hook up a midi keyboard or any kind of controller to control the frequency?</p>
Without a looooot of extra electronics, not easily. The MIDI protocol is based on &quot;events,&quot; like &quot;note on&quot; and &quot;note off,&quot; whereas something like this is analog audio and relies on continuous signals, often called &quot;Control Voltage&quot; or &quot;CV&quot; signals in the analog synthesis world. So, you'd first have to purchase or construct a MIDI to CV converter.<br><br>Additionally, you'd have to alter the circuit to allow for a CV input (which I've intended to do for a while, just have never gotten around to it!), so unless you're quite familiar with analog circuit design, I'd say it's probably best to just stick to what's in here.<br><br>If you've got a MIDI keyboard, I'm guessing you've got some sort of software that could almost definitely synthesize a square wave (I know, not the answer you were looking for, but that's part of this device being so simple, is it doesn't have a whole lot of bells and whistles).<br><br>So sadly, in short, no. =/
<p>Any idea how this can be modified to get a SIN and TRIANGLE Wave Oscillator as well ?</p><p>Thanks and great instructable!</p>
<p>Try looking up 4 op amp function generator. That should give you enough to figure out how to get a pseudo-sine and triangle waves.</p>
<p>I have not personally done it, but it should be possible! In step 4, I denote which portions of the circuit are the Power Supply, Output Volume, and Oscillator portions of the circuit. If you pull out the oscillator portion (that's a square wave in this case) and replace it with circuitry that's readily google-able for a Triangle or Sin wave oscillator, it *should* work. No absolute guarantees, but if you were able to get this one to work, that's a good next step!</p>
<p>not really square but more ramp square combo.<br></p>
<p>Looks like it's working! My guess is that the oscilloscope sampling/triggering might be slightly off, and that's what's causing the artifact ramps.</p>
<p>.the generator works great...i just wanted to ask why have you connected the frequency control part to the inverting input in your schematic as opposed to the traditionally used non-inverting input? Is there any distinct advantage?</p>
<p>Nope, no distinct advantage. The circuitry is a little simpler when using the inverting input. There's a fair amount of mathematical and theoretical circuitry explanation as to why, but that's the short end of it.</p>
<p>Great project. The video at the end was very good to see - shows that what you build really is useful.</p>
<p>Thank you! Glad you like it!</p>
<p>Hello, I have been working on this project for a few days and am having a little trouble. A quick question if I may.. is the ground rail connected to anything? Perhaps it would be the negative side of either the 9v battery or 4.5v rail. Or does it just standalone? Any help would be appreciated, cheers :)</p>
<p>Nope! The &quot;ground&quot; in here is just the &quot;reference&quot; point - doesn't refer to any actual grounding. If I were to be *technically* correct, I would use the word reference instead of ground, haha.</p><p>Anyway, the ground rail is its own rail, and it is the &quot;0V&quot; reference. It's sort of a goofy thing to wrap your head around at first, but by putting the reference &quot;in the middle&quot; of the 9V battery, it makes the + side of the battery technically +4.5 volts, as compared to the reference, and the - side -4.5 volts, as compared to the reference. This allows the op amp to create both &quot;positive&quot; and &quot;negative&quot; voltages, but all in reference to the ground. Hope that makes sense.</p><p>Short answer - nope, it's its own thing!</p>
<p>Could I easily add an external input to this oscillator?</p>
<p>I Made it! It was my first project. Everything worked fine, except for the volume. It is very low after I soldered it. Might it be, that I only use a 10k R, instead of the 2 x 10k in series or the 20k connected to the ground?</p><p>Anyways, connected it to my sound interface and it sounds pretty cool. Planning now on building some effects to modulate the sound.</p><p>cheers from Germany :)</p>
Glad it worked for you!<br>Not sure about the volume knob - could be a cold solder joint or something.
<p>can I use a lt1019 or 1013 op amp?</p>
<p>The 1013 would work just fine, but be sure to check the pinouts so that your - and + inputs and output line up with the corresponding inputs in the schematic.</p>
<p>Hello! :) </p><p>Great tutorial! but I have tow questions. Where is the eagle file? And what kind is your perf board? Is a board that needn't design? Is better this or make my board? </p><p>Thanks in advance</p>
Just realized I haven't uploaded the eagle file - I will get that up soon!<br><br>The perf board I used in the instructable is just a general purpose general design perf board (I have a link to it to buy something similar on Newark in the &quot;gather your parts&quot; step).<br><br>The general perf board will be a bit cheaper, but you have to do a bit of design to get all the nodes to line up correctly, whereas the eagle-designed PCB is an easy way to just place your parts exactly where they need to be. The other advantage to the Eagle PCB is you can skip the breadboard part of it, and build it directly, though that's not as fun!<br><br>If you want to alter or expand the design in any way, the pre-fabbed PCBs can be restrictive depending on what exactly you want to do.<br><br>Hopefully that helps!
<p>Okey, thanks for your reply :) Another question, where I buy my components, there aren't a capacitor 0,001uF with 1600V (like your list). I can buy one of this but 630V. Is there a problem? Thanks!</p>
<p>Nope, that's a maximum voltage rating for the capacitor. the maximum possible voltage we'd see across that capacitor in this circuit is 9v, so one with a 630v rating is 100% ok!</p>
<p>Hello:)</p><p>My first project in this area, had success from the start that I attribute to the author.</p><p>cant wait for the next one.</p><p>Cheers</p><p>Steve </p>
<p>Thank you very much! Glad to hear it worked!</p>
<p>hi ! looks like a great and fun thing! im out to make one. as for the 741 op amp, i ordered this thing- </p><p><a href="http://www.taydaelectronics.com/ne5532-5532-ic-dual-low-noise-op-amp.html" rel="nofollow">http://www.taydaelectronics.com/ne5532-5532-ic-dua...</a></p><p>is it the right componenent? will it work?</p><p>thanks</p>
<p>Yep! It will work, but you'll have to change the pin numbers from my schematic, as the 5532 is a dual op amp (there's actually two of them in the package), and the 741 is a single. Here's a translation for you, with the 741 pin on the left, your 5532 pin in the middle, and the explanation of that pin on the right:</p><p>2 -&gt; 2; Negative input</p><p>3 -&gt; 3; Positive input</p><p>4 -&gt; 4; Negative rail</p><p>6 -&gt; 1; Op Amp Output</p><p>7 -&gt; 8; Positive rail</p><p>Hope that makes sense, thanks for trying it out!</p>
<p>Hello and thanks for this awesome tutorial! I'm going to make my own version of it next week (when I get the parts). Does the cable out of OP amp 5 go directly into the oscillator cable or is it connected to the frequency pot and R8? Just to be sure. I'm going to build exactly this oscillator except for that I'm going to put 5 potentiometers parallel next to each other with each a button in series, so you can play it like a piano (except more notes together won't work). Thanks for inspiring me to do this for my physics assignment and giving me this awesome tutorial!</p>
<p>I should have looked better at the breadboard schematic. I already know the answer</p>
<p>Glad you got it figured out!</p><p>Regarding the switches and frequency, as long as you're doing your calculations with the series/parallel resistors, it should work! Just note that pressing multiple switches with the resistors in parallel will cause the resistance of that leg to decrease, which actually causes the frequency to increase. So, you won't be able to &quot;play&quot; the keyboard without a lot of care being put into making sure the switches aren't pressed at the same time.</p><p>The other note I will make is that the switches, when unpressed might also have some erratic behaviour, as the oscillator may still oscillate, but at a very low frequency. I would suggest using SPDT (Single Pole, Double Throw) switches, with the second pole connecting across the oscillator output. This will &quot;Gate&quot; the oscillator off of these switches as well as change the frequency, so if none of the switches are engaged, literally nothing is coming out of the oscillator!</p><p>Hope that helps</p>
Thanks for the info. I've just got it working with one note! I'm aware that I can't play more notes at the same time but I don't know what kind of switches I have. I'm going to &quot;tune&quot; the potentiometers by putting them through my computer, so I will see low notes if that's the case
<p>Awesome! Thank you for sharing that; just what I've been looking for! I want to build a simple tone generator for syncing two multichannel sound recorders. I'd need to adapt your schematic to incorporate an extra mono output and a 'push to make' momentary switch to trigger a simple pulse tone for sync-up. I'm a bit of a noob to electronics; just a few veroboard stompbox fx layout builds and the odd guitar wiring harness under my belt. I don't suppose you could tell me the best way to incorporate a second mono output and a momentary off/on push button switch into your circuit design? </p>
<p>For the two mono outputs, you've got a couple options:</p><p>Two separate volume knobs:</p><p>On the schematic, the portion that is labeled &quot;Volume and Output Section,&quot; basically repeat that, and connect the incoming line to the same wire marked &quot;Oscillator Output&quot;</p><p>One volume knob for both outputs:</p><p>For this I would just add a secondary jack, with the sleeve connected to ground, and the tip connected to the same wire that the tip of the first jack is connected to.</p><p>For your momentary, I'd put a momentary switch in line right where it says &quot;Oscillator output.&quot; So, instead of that output going to the volume and output section, it goes to the momentary switch, and the output of that momentary switch is what goes to the volume and output sections.</p><p>Hope that helps!</p>
<p>Got it working! I couldn't find a 741 so I used 778a instead. Changes the pin out quite a bit but allows for a dual OSC. </p><p>That changed pinout tripped me up for a little bit</p>
<p>Cool! Glad you got it working! The dual oscillator could be cool if you add another pot for frequency - you could then either sum them or just mix between the two!</p>
<p>on the fritzing diagram, you have a green wire running from V- down row 22 to E. What is that doing?</p>
<p>It uh.... doesn't do anything. Good catch! I'll change that and reupload it!</p>
<p>This project was the first electronics project I've ever tried, and I managed to get it all to work the first time, so woot! I bought my supplies locally and followed the breadboard image. I couldn't match the exact circuit as my cheap breadboard only had 2 rails, so I made do. I was amazed that it worked properly the 1st time I powered it up. Thanks! My only request - if someone figures out the mod to give it more of a frequency range, that would be great. My next step is to transfer the osc into a project case so I can take my bleeps and bloops with me.</p>
<p>That's great to hear!!! I love it when somebody can complete it successfully - it really means a lot to me!</p><p>For the frequency question, I&quot;m just going to copy-paste a response I gave to a similar question below:</p><p>Using the schematics shown, you get roughly 207 to 310 hertz. What controls the frequency in this one is the 500k&Omega; variable resistor and the 1M&Omega; resistor connected to it (top center of the schematic) To achieve higher frequencies, lower the value of the 1M&Omega; resistor, and for lower frequencies, raise this resistor value. To achieve a larger sweep, get a larger valued variable resistor.</p><p>If I had to do this again (who am I kidding, I probably will!), I would change the 1M&Omega; resistor to a 300k&Omega;, and make the 500k&Omega; variable resistor a 5M&Omega; for a larger range, extending from 60Hz to 1KHz.</p><p>The math for all this is explained on this page (there's even a handy calculator at the very end if you're feeling adventurous enough to try even more values):</p><p><a href="http://hyperphysics.phy-astr.gsu.edu/hbase/electronic/square.html" rel="nofollow">http://hyperphysics.phy-astr.gsu.edu/hbase/electro...</a></p><p>Keep blooping!</p>
<p>Hi, just wondering why there is a differing amount of resistors in the the fritzing diagram and the accompanying image of the breadboard? Also which image should I follow as Im new to all this and planned on matching what I have to the image on here to produce it that way? As well as that im wondering why the arrangement of the two images im talking about is different in terms of where the components are placed. Any help is appreciated :) cheers.</p>
<p>Im struggling to identify which resistors are which too on the fritzing diagram </p>
<p>The resistors are identified by resistor color codes. Here's a code calculator and a chart:</p><p><a href="http://www.digikey.com/en/resources/conversion-calculators/conversion-calculator-resistor-color-code-4-band" rel="nofollow">http://www.digikey.com/en/resources/conversion-cal...</a></p><p>As far as the differing number of resistors, I'm assuming you're referring to the 2x 10k&Omega; resistors vs. the 1x 20k&Omega; resistor? Those two are basically the same thing. 2 10k&Omega; resistors running in series just adds up to 20k&Omega;, so whether you have 2 10s or one 20, it's the same thing.</p><p>Long story short, in electronics there are multiple ways to do things yet still be what we call &quot;Electronically equivalent.&quot; It's the same idea as 4x2 is mathematically equivalent to 4 + 4.</p><p>Honestly I would go off of the schematic instead of the pictures of breadboards, as you can lay out a breadboard an infinite number of ways and still be electronically equivalent; the schematic actually defines the connections. If you don't know how to read a schematic, there are a number of great tutorials online to help you along the way. Here's one from sparkfun: https://learn.sparkfun.com/tutorials/how-to-read-a-schematic</p>
<p>hi, this is what i have so far but it isn't currently working. I replaced the speaker with a simple 1/4&quot; jack output so im not sure if its that, is there anything noticeably wrong with this breadboard layout as ive tried general trouble shooting but to no avail. Thanks in advance :)</p>
<p>Troubleshooting breadboard pictures is relatively difficult, but it just looks like there's a lot of stuff in the wrong spot. Take for instance your ground, which is the black wire coming off of those two resistors around rows 35-40; that is plugged into the positive rail of your breadboard, but nothing else is. There should be a lot going to ground. It also appears as if your 1/4&quot; jack is just plugged into the 9v + and -, which won't get you anything.</p><p>I would also recheck the pinout of the opamp, as that doesn't look entirely correct at first glance.</p>
<p>Your not wrong they are haha. Ive decided to start over using the fritzing diagram as a guide. The result was the same though unfortunately, this is it at the minute, same rule goes I haven't got a clue as to whats wrong with it. Im starting to understand the basics of schematics but need to complete this for a uni project so worry I wont have time. Also do the numbers shown on my breadboard differ from yours and the fritzing for any particular reason? Again, your help is much appreciated!</p>
<p>That looks much better! I can't completely tell in the picture, but that 1M&Omega; resistor looks like it might be going into pin 3 or 4, when it should be going into pin 2. Might be just the angle of the picture.</p><p>What I would do next is bypass all of the output management stuff. So take the positive/tip output of your 1/4&quot; jack and put it directly at pin 6. There you should get the square wave without any attenuation. The next thing to check is to make sure that your power supply is actually spitting out 9 volts. Hopefully you have a voltmeter or something of the sort. (Or just make sure your LED is lighting!). The last thing is you may have blown the op amp - which is not difficult to do.</p><p>Hopefully something in there helps!</p>

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