Noisetendo NES 555 Synth

NOISETENDO, the Nintendo Game Controller 555 Synth



I’m hoping I’m the first to give birth to this, but it’s very likely I am not considering there are way more people better and more creative at circuit bending than I.  That being said, if you’re a novice and you want something really fun and relatively easy to do, this is a great project;  turning an old nintendo NES game controller into a tri-tone synth that actually works when you press the buttons!!  I call it the Noisetendo, you can call it bad ass!


REVISION:!!!  NOT EVERY BUTTON CHANGES A TONE.  I found out after going through each pin with various amateur wiring methods, I could only get two tones out of it, well, three really.  The reason is that I’m still using the onboard chip in the controller for its conductive path.  If you find a better way to do this, I’m all ears.


This project involves very few parts believe it or not, and the parts can all be acquired through one stop at fry’s or radio shack — except for the NES controller..  that you’ll have to scavenge around for. By the way, if you want to actually play some old NES games, go to this link, they are java games and don’t require installation of spyware:






My goals for this project were:


1)  to use the existing chip somehow to power the existing switches and NOT have to do contact switches myself, that would be ugly.  I also wanted to keep the front face of the controller as clean and unchanged as possible, to where it still looked like the original NES.  So far so good, but there’s always room for improvement, so this is a beta version.  Hopefully other folks will join in and make some different versions that are different and more functional.


2)  I didn’t want any digital crap.  I wanted pure analog, so there’s no arduino or PIC controllers.  I also didn’t want to solder a board, at least not now, so I used some breadboard in this version and just taped it to the bottom — yes, tape.


Biggest problem you will face is that the controller has a very slim profile and there’s little to no room to put wires or components INSIDE the shell… so, I resorted to mounting stuff on the back of the controller, being careful not to poke too many holes in it…  remember, these things are antiques now!!



I am high school science teacher in real life. If you like this hack, or just had fun messing around with your NES controller, please consider a tiny donation. All the money goes to making more electrical projects for my students. I am one of the few teachers out there who shows students how to use a soldering iron, and teaches quantum mechanics to 16 year olds. Any amount, no matter how small, helps!!



1 X NES Controller

1 X 555 timer

1 X 104 ceramic capacitor, or, 0.1 uF cap, electrolytic is OK too

1 X 9volt battery, and holder

1 X 7805 voltage regulator, brings 9volts down to 5v

1 X 500k Ohm potentiometer, yes, that’s 500,000 ohms, 100k will work too

1 X LED, any size, but small enough to fit into the O of the word NINTENDO on the front face.

1 X 3.5mm standard audio jack

1 X 10k resistor

prototyping board / breadboard

Jumper cables



FIRST THING FIRST:  YOU MUST BUILD A 555 SQUARE WAVE VARIABLE FREQUENCY OSCILLATING GENERATOR prior to doing any of this.  If you can’t get the sound produced, you can’t trigger it with the NES controller…  Here is a standard diagram for just the noise maker you want to do with a 555.  Remember, the output is simply the POSITIVE lead of a speaker, then you connect the NEGATIVE lead of the speaker to the ground of your 555 circuit.






The NES controller has a chip in it called a HD14021 BP , or, just a 4021 for short.  this takes the input from 8 buttons and sends them as data pulses to the NES box.  In my method, I wanted to use the pins of the buttons to activate the 555 timer to make noise.  I had no need for the data function of this chip, I just need the on / off conductive path provided by the switches in the button pads.  If you want to see the official pinout of a 4021, go to this page —


So I had to draw a map and trace out visually what pins lead to which button and this is what I got:



4 – UP

5 – DOWN

6 – LEFT


13 – START




I soldered some test leads to various pins and powered them up, things seemed to work, but I had some weird problems with the conductive path on that chip – discussed later below.



ABOVE:  the battery has been mounted, the cable has been severed and a standard yet small 3.5mm audio jack put in its place. the 555 timer board is being voltage regulated by a 7805 regulator.  If the reg is facing you with the writing, the pinout for the reg is:


left leg:  incoming, unregulated voltage (9V in this case)

middle leg:  ground, negative from the 9V

right leg:  5V outgoing voltage / regulated voltage




above;  this was my first test circuit with just one 10k resistor running from pin 7 of the 555 to my 5V power rail.  the wires coming out of the hole in the NES go to the LED in front and the audio jack.  The positive lead of the LED goes to the 5V power rail, the negative lead goes to pin 3 of the 555.  The audio jack has no polarity, so plug one lead into pin 3 and another lead into power.


MOST IMPORTANT STEP:  Solder a line from pin 7 of the NES controller chip and connect it to the 10k resistor.  Then solder a wire from pin 13 and connect it to pin 3 of the 555.  This is critical.  When I was going through the wiring, I found out that only pin 7 would allow the buttons to be used in an OFF state rather than always ON.  You can experiment on your own, but this is what I discovered.  So, you’ll only use pins 7 and 13 of the chip.






above:  IT’S ALIVE!!!!!!!!!!!!!!!



Looking at it this way, the pins go like this:

TOP LINE:  9, 10, 11, 12, 13, 14, 15, 16

BOTTOM LINE:  8, 7, 6, 5, 4, 3, 2, 1




screwing in the 9v battery holder is a breeze, highly recommended.






3.5mm audio jack fits snugly in this spot with a little dab of hot glue.




up close on the pad and chips, I recommend you label everything with sharpie.