Photograph by Sam Murphy

Hack Electronic Pushbuttons

Tap into your electronic devices and take control.

By Peter Edwards

IN THIS TUTORIAL I’LL EXPLAIN HOW you can easily hack the controls of almost any electronic device. Why would you want to? Maybe you want to rewire a Nintendo joystick to your computer so you can control Mario via Max/MSP. Maybe you want to set up magnetic sensors to steer a remote control car while you’re tap-dancing. Or wire the buttons in your TV remote to big, arcade-style buttons mounted in your coffee table. Or modify a musical instrument (as I’ll show here). There are countless possibilities.

This guide applies to most button-hacking projects but there are always exceptions to the norm and baffling anomalies. These techniques will work for many circuits but not all.

What’s a Button?

A pushbutton is a simple electromechanical device that makes or breaks an electrical connection when activated. Hold 2 pieces of wire in your hands. Connect the ends together, now disconnect them. You just performed the functions of a pushbutton.

There are many varieties of pushbuttons but the most common (and simplest) is the momentary SPST (single-pole, single-throw) switch. This will often be listed as “(NO)” which stands for “normally open.” The parentheses around NO tell you it’s a momentary switch — the circuit stays closed only while you keep your finger on the button.

This button has 2 connection terminals or nodes. Activating (or pushing) the button connects these terminals together. That’s it! This sends a signal to the circuit telling it to do something specific. It doesn’t matter how the nodes are connected; all the circuit knows is that they are. That means anywhere there’s a button, you can replace it with another button, a sensor, a relay, or any other means of passing and breaking current flow. As long as the nodes connect and disconnect, it’ll work.




The cheapest and most common style of button used in consumer electronics. It’s easy to install and can be made in a wide range of shapes. When you press the button, it pushes the conductive rubber membrane against 2 interlinked sets of “fingers,” which are printed on the board in conductive ink.

Pros: Cheap and reliable.

Cons: This style of button requires special fabrication techniques that are unavailable to hobbyists. It’s also the most difficult style to hack, and because it’s made of conductive rubber it can handle only very low current.



Used where conductive rubber isn’t feasible, or in higher-current applications. This button is cheap, easy to use, and easy to hack. A tactile switch has 4 legs; the legs across from each other are typically connected internally.

The only drawback for hobbyists is that it must be board-mounted, which presents challenges over panel-mount pushbuttons.

Pros: Cheap and reliable, easy to hack, low resistance, can pass higher current than rubber switches.

Cons: Small, must be mounted on a circuit board.



Rarely found in consumer electronics but a favorite with hobbyists. These switches are the most versatile but also the most expensive and, relative to tactile and rubber switches, the most delicate.

Pros: Easy to use, available in many different configurations, can handle high current, very easy to hack.

Cons: Much more expensive than other kinds of buttons. More moving parts, therefore more delicate.

Illustration by Peter Edwards

imageCAUTION: As always, only work with battery- powered electronics or circuits that are powered with a wall wart adapter. Don’t tinker with circuits that plug directly into the wall unless you know what you’re doing and are qualified to work with deadly voltage levels.

Just make sure the button you use can handle the electrical current that will pass through it. This article only covers low-current circuits and buttons.

Let’s Hack Some Buttons

I like making music, so I decided to hack the buttons in a bunch of musical toys so that I could control them all with a sequencer. I selected 3 Casio keyboards — one for the drumbeat and 2 for the melody — and 3 voice memo recorders to sample and play back the sound from the keyboards, introducing all kinds of interesting variables into the music.


Soldering iron, solder, and insulated wire

NPN transistors general purpose

Resistors, 10kΩ (optional) and 100kΩ

Arduino microcontroller Maker Shed,


Multimeter with continuity tester

Mini screwdrivers for opening electronic devices

1. Identify the buttons you want to hack.

Let’s look at the Casio SA-38. This keyboard is useful because it has 5 big drum buttons (Figure A, following page). I can hack these and sequence them to make drumbeats.


2. Open it up.

Once you open up the keyboard, you’ll see 3 circuit boards (Figure B). The green board handles power and audio. Underneath it is a brown board with a big chip on it. This chip is the main brain of the keyboard, so I’ll call this the brain board. This board and the third board alongside it hold all the conductive rubber pushbuttons. The brain board has the function buttons, including the drum buttons I want to get at (shown by the red box). The third board has the keyboard buttons.


3. Find your buttons.

Unscrew the brain board and turn it over. Now you can see all the button contact points. The 5 drum button contact points each have 2 nodes (Figure C). These nodes look like 2 hands with their fingers interlaced.


4. Connect your wires.

The contact nodes are printed on the board in conductive ink, which is impossible to solder to. Follow the leads trailing away from each node and you can see that one node of each button is connected to a solder point nearby.

You can also see that the bottom nodes of the 3 leftmost buttons are connected together, and so are the 2 right buttons. This is a common trick used in digital circuits to trigger several functions with just a few pins. There’s no obvious solder point near these nodes, so use your continuity tester to find their 2 solder points elsewhere on the board.

Solder a wire to each node’s solder point, then test it by touching the ends of your wires together to trigger each sound. Finally, write down the button configuration. I use colored ribbon cable to make this easy (Figure D).


5. Hack more buttons!

The Casio SK1 keyboard lets you record sequences then play them back one note at a time by pressing One Key Play. I hacked this button so I can control playback (Figure E).


Photography and diagrams by Peter Edwards

On the voice recorders, I hacked the Record and Play Back buttons (Figure F). Any simple voice recorder like the Velleman-mk195 can be used (see Maplin, KitStop, etc.).


6. Choose switches to interface with.

To replace a conductive rubber switch, you can use any of the following:

High-Voltage/Low-Resistance Switches

» Panel-mount and tactile pushbuttons

» Magnetic reed switches

» Relays

Low-Voltage/High-Resistance Switches

» Transistors (My favorite! See Step 7.)

» Switching ICs (such as the CD4016)

Panel-mount pushbuttons and relays are necessary for low-resistance, mid-voltage (more than 1V) applications such as passing audio signals or powering circuitry.

For the sequencer shown in Figure G, I used relays as my switching mechanism to allow for the greatest variety of application. Plans for building your own analog step sequencer are available at


7. Connect hacked buttons to the Arduino.

I use an Arduino microcontroller and some additional transistors to trigger the buttons I hacked. This is a very flexible method that I also use to interface devices with my modular synthesizer.

Transistors are small, cheap, and amazingly powerful. I use general purpose NPN style, 2N3904 or 2N2222 (Figures H and I). I’m sure lots of other transistors will work.


Wire up the switch as shown in Figure I, and test it on a breadboard before soldering. This configuration will work in most cases, but experimentation may be necessary. If your hacked device is triggering erratically, install a 10kΩ resistor to ground (as shown in Figure I). If it’s still acting up, try increasing the value of the 100kΩ resistor. If it’s not triggering, reduce the value of the 100kΩ. If it still doesn’t work, try different transistors. There’s a combination out there that will work!

Next connect one of the digital outputs of your Arduino to the transistor through the 100K resistor shown in Figure I. When the digital output pin goes HIGH it will trigger the hacked button. Start with the Arduino “blink” code to get started. Connect pin 13 of the Arduino to the transistor. Now the hacked button will be triggered every time the light on the Arduino blinks. image

NOTE: You must connect the ground point on the circuit you’re hacking to ground of the Arduino. If you’re using battery-powered electronics, just connect the negative battery terminal to the GND pin on the Arduino. If you don’t do this, it won’t work.

Peter Edwards is a circuit-bending and creative-electronics pioneer in Troy, N.Y. He builds electronic musical instruments for a living at Casper Electronics (

..................Content has been hidden....................

You can't read the all page of ebook, please click here login for view all page.