The AMC 12A8 Servo Amplifier was used to send the impulse current to our electromagnetic drum. It is capable of handling 20-80 volts and a peak impulse current of 12 amps (6amps continuous). The amp was used in "voltage mode", were an output voltage was determined from a reference input pwm sent from the Arduino. We initially tried to use the amp in "current mode" but found a parasitic current was always sent to our drum, not ideal for our setup. While in voltage mode we tuned the potentiometer gains while the amplifier was connected to an oscilloscope to provide a maximum output current from the pwm signal.
The amp was connected to (4) 25V power supplies, 2 connected in series, 2 in parallel to provide 50 V and twice the amperage. This resulted in a reasonable repelling force.
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This is a very interesting blog! This project was very enjoyable and I liked feeling the drumstick bounce back from the drum head. I also liked the sound produced from your instrument. It sounded like a real tom-tom and cymbal being hit.
ReplyDeleteI think its a great idea to try and provide feedback for electronic drums. Anyone who has played "Rock Band" knows that the pads that they use are pretty terrible. It was very interesting to play and feel the feedback that was created without the stick physically touching anything. Sound synth was also top-notch.
ReplyDeleteThe photo-gates were a very good idea for proof of concept; you probably considered using accelerometers in the stick, which would be difficult but ultimately more useful so that those vertical bars arent in the way when switching from one drum to the next.
It would also be interesting to figure out how to develop a field evenly over the whole area of the drum to make it a little more playable, ie the drum strokes dont have to be so precisely directed. I dont know if that would take an array of smaller coils or what. Couple that with one of those IR sensors that tracks position by painting any surface w/ IR light, and you can synthesize the sound differently depending on where the drum is hit to make it even more realistic. Obviously that would be way too much for this project; you guys did a great job with it.