Figs. E and F: Finishing up the solenoid-powered drumstick. Mount it to the pivot stick, directly above the
solenoid, then secure it to the solenoid.
Fig G: You can make drums with a plastic tube,
a balloon, and some tape. Fig. H: Feel free to display
the MIDI decoder kit as part of your Drumbot system.
NOTE: Some parts will only work if oriented properly,
so make sure they’re pointing the right way before you
solder them in.
should be able to see the LED nearest the kit’s MIDI
jack blinking with every message sent. Neat!
3. Build the drum strikers.
2. Attach power supply Here’s where the fun begins. As the kit receives
and your MIDI device. a MIDI note on/off signal, it opens and closes the
Once the pieces are in place, attach your battery or 8 relay switches. All we have to do it attach ready-to-power supply. The LEDs will light up and the power go electric motors or solenoids, and it’ll fire those
LED will remain lit. If it doesn’t seem to power up, off in sequence.
check all your solder joints and fix any that are loose DC motors work well with this kit, but the
or have bridged together. real drumming action will come from solenoids.
Next, attach a MIDI cable to connect your MIDI- A solenoid (Figure C, previous page) can be thought
generating device to the kit. Set your device to send of as a linear DC motor — rather than rotating a
a continuous stream of MIDI notes, then take a look central shaft, solenoids use an electromagnetic field
at the MSA-R firmware documentation (PDF at to propel the shaft outward. Most have a spring at-
makezine.com/go/msafirmware) and set the DIP tached that reloads the shaft after each propulsion.
switch so that it’s “looking for” the range of notes They’re perfectly suited for tapping/striking actions.
your MIDI device is sending. A simple way to employ solenoids is to prop them
The MSA-R kit will only “see” a range of 8 con- up such that they tap on a hard surface. Cardboard,
secutive MIDI notes, so you’ll have to make sure wood, and plastics all make different sounds when
communications between the kit and your device struck, and drumheads sound even better. However,
are happening in the same note range. Once you if you want louder and more powerful strikes, you’ll
get the 2 devices set to the same note range, you want to construct a lever system that will use the
62 Make: Volume 15