CIRCUITSDIY
function buttons, including the drum buttons
I want to get at (shown by the red box). The
third board has the keyboard buttons.
A
3. Find your buttons.
Unscrew the control 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.
C
B
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).
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
E
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).
On the voice recorders, I hacked the Record
and Play Back buttons (Figure F). These samplers are easy to mod and cheap to buy from
All Electronics ( makezine.com/go/recorder).
Photography and diagrams by Peter Edwards
118 Make: makezine.com/26
