Fig. G: The drum controller’s connection to the serial
cable. Fig. H: Remove the coating from the upper right
drum pad button contacts. Fig. I: The drum machine
6. Connect the drum machine.
6a. Bolt the project box to the drum machine, pass
the male serial cables through ¼" holes drilled in
the sides, and strain-relieve them with cable ties.
Mount the push-button switch on the side of the
project box and solder it to the pair of wires from
the drum machine’s Function switch.
Follow the online schematic to connect the rest:
solder the +V (pin 14) and Ground (pin 7) of one
of the 4066 chips to the V+ Power and Ground of
the drum machine circuit board (Figure E, previous
page). Connect the pad button leads to the quad
switches’ signal pins. Connect the Pad Bank leads
to pins 1 and 2 of controller #2 (Figure J).
6b. Plug the 2 drum controllers into the circuit,
and you’re ready to play. The circuit gets its power
from the drum machine, so you should see its LEDs
light up when you hit each pad. If they don’t, swap
controller cables to determine whether the problem
is with the controller or the circuit. Since we wired
directly to the pads, all the functions of the drum
machine will still work. Pad 5 controls the Bank
92 Make: Volume 15
button pad contacts, wired. Fig. J: The pulse circuits
wired to the serial cables and drum machine.
select. Strike it to select an alternate drum set.
Enjoy your electronic drum set. Bust out some
beats and start a band!
For project schematics, and video clips of disassembling a Zoom MRT-3B and playing the Electronic
Drum Kit, visit makezine.com/15/electronicdrum.