Arduino Opta Drum Machine

After obtaining an Arduino Opta micro PLC, along with the new Arduino Pro Ext D1608S solid-state relay (SSR) expansion module for an online class, I decided to have a little fun and create a robotic drum set. This auto-drummer features an external solenoid that hits a small hand drum, along a second solenoid that hits the system’s metallic power supply to ting out an additional beat. A third bit of percussion comes from the Opta’s four internal mechanical relays. These all hit together to output a fast "hi-hat" that pulls everything together in the video below.

The device’s external solenoids are held in place via a pair of friction arms–normally used for camera equipment – along with a 3D-printed zip-tie adapter. This allowed for a quick mechanical setup and easy adjustment to get the drumming action just right.

Electronics-wise, the Arduino Opta’s relay output setup means that wiring was a matter of providing power to the Opta/expansion module, as well as the relay outputs via screw terminals. The external solenoids were screwed into the appropriate outputs and connected to ground. Ground and power banks were made out of lever nuts, making for quick wiring work without the need for solder.

Power for the build is through a variable voltage supply. 12V is the nominal input here, but this can be varied up or down to vary the beat intensity. Of course, one might argue an enclosure and DIN rail setup would be appropriate – and that higher or lower than 12V is out of spec per the combination of Arduino and solenoids used – but it worked well enough in my closely monitored testing. Code is found here, but be sure to take the proper precautions if you try something similar!