A while ago, I decided that I wanted to build an analog modular synth. After doing some research, I found out that I didn't know all that much about analog audio electronics at all. So the best thing to do was to start from the very beginning and to build all kinds of simple oscillating circuits to get a grip on the basics.

When you google for simple oscillators, you inevitably come across the stepped tone generator aka the Atari Punk Console (APC). The circuit was first published in 1980 by Forrest M. Mims III and was later slightly altered and renamed Atari Punk Console by Kaustic Machines. They gave it that name because its sound resembles that of the old Atari video game consoles.

When I did build my first APC, I quickly discovered why it is so immensly popular. It is very cheap and easy to build and it produces a lot of weird and funky noises with very few parts.

The only thing that, imho, is missing in 90% of the available circuits online, is a way to add an external voltage control.  It can be done by adding only two extra female Jack connectors to the two free pins on the 556 timer. WIth these two extra connectors, you can add an external oscillator, LFO,...

Step 1: What Do We Need for This Project?

  • A 556 dual timer
  • A 1K resistor
  • An LED of your choice
  • A resistor for the LED. In my case a 470Ohm
  • A 100nF and 10nF capacitor
  • A 10uF electrolytic capacitor
  • 2 x 470K or 500K potentiometers
  • A 100K Logaritmic potentiometer or a 100K and 4K7 resistor
  • A switch
  • 3 female jack connectors
  • A DC connector
  • A 9V powersource
  • A case. I used a plain and ready available project box. But google for Atari punk console and be amazed about all the weird and wonderful housings for this device. I am sure that you can come up with one of your own.

Step 2: The Circuit

The circuit is basically 99% the same as the original Forrest M. Mims III design, except for the 100K potentiometer that I added for volume controle. The LED and switch are optional.

For the voltage controlled bit, I just added a female jack to pin 3 and one to pin 11 of the 556 and that does the job.

Building the circuit is really easy and you should definately try to tweak it or to add your own bits. 556 ic's are really tough and can survive a lot of electronical abuse!

I added the eagle file of the board fot those who would like to use it. The board has 2 options for output: eIther a line level or a volumecontrol.
  • For line level: Add the 100K and 4.7K resistor and connect the rightmost pad and the centre pad of the potentiometer.
  • For a volume control: Add a 100K potmeter and connect directly from the 10uF capacitor to the rightmost pin of the potentiometer.
<p>hello, i'm very new with electronics, i got the 556 timer but your drawing is with the two 555's</p><p>i'm a bit confused over how to connect everything to the 556..</p><p>thx in advance..</p>
<p>Thats Not 2 555's, its the 556 split into 2 parts. just follow the pin numbers.</p>
this is a link to a circuit for an atari punk console with a 556 ic. The two pins that are not used in this schematic can be used for the cv input. http://www.jameco.com/Jameco/workshop/diy/ataripunkconsole-kit-fig4.jpg
<p>thx man, gonna give it a go!!</p>
<p>Sounds great! Thanks for instructable.</p>
Looks great!
So I made an apc with two cv inputs. If I connect a step sequencer to one are there limits as to what I do with the other? Will it matter which cv Jack I use? What if I were to connect a sequencer to each cv input?
<p>Why the two jacks for the CV input? Is it one for each oscillator?</p>
It's indeed 1 for each oscillator.
<p>Yours is the only design I've come across to do that. Very nice. Just one more question. Could the switch be a simple SPST toggle? As far as I can tell that's the function of it on the schematic. Or have I missed something?</p>
Yes that should do.
<p>So I made it. Actually it took me a while to figure out, that the ground on the schematic is supposed to be the negative pol of the power supply. Isn't ground and the negative pol a different thing?</p><p>Anyways, I think the idea of adding 2 CV is great. What types of cv can I add there? </p><p>I built the apc in a bigger wooden box, so I can place there some lfo, fx... or a sequencer, to have diretly a modular system connecting the apc in different ways</p>
Somethimes gnd and negative are two different things but with battery operated divises it's almost always the same. You can add any cv you want. You can add an ldr or other sensor....
<p>how would you go about connecting two consoles together?</p>
How would you like to connect them. In other words what is the desired end result? An easy way to connect them is to feed the output of one into one on the VC inputs of the other.
Well I was thinking of creating two and then combining them together to one output? Maybe chuck in a filter after them as well..basically I'm trying to design a synth by combining pre designed parts if you get me?
where did you get the pcb?
I designed and etched it myself.
Can you upload the file you used?
I added the eagle file for you. Read the note that I added on the last step about the output.
<p>Any chance for the SCH file?</p>
thank you!
could someone tell me what program the circuit was drawn on
I draw all my circuits in Eagle.
Congratulations on being a finalist in the DIY Audio Contest!! Good luck to you!
Thank you!
All the other APC only use one 556. Is the second one here need for the output mods? I am obviously very new to this, so please be kind ;)
Never mind, I just figured it out!!!
No problem, I myself am also sometimes confused when seeing those broken up IC schematics.
cool project - if you want to build another cool little instrument I have a stripboard layout for a theremin thats pretty easy to build - it's an Aerial version not an LDR one<br> <br> <strong><a href="http://www.paulinthelab.com/2012/04/theremin-veroboard.html" rel="nofollow">HERE</a></strong>
It makes a great sound! I've put it on my 'to make'-list.

About This Instructable




Bio: I'm mainly interested in music, food and electronics but I like to read and learn about a lot more than that.
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