Introduction
This tutorial will explain how to build your own double-kick Bass drum pedal mod for Rock Band. We have also included a video demonstration of the double kick from the guys over at imakeprojects.
What This Is The game ROCK BAND has a drum set complete with a Bass drum pedal. Because there is only so fast you can work the pedal with your foot, if you want real speed you need TWO pedals - one for each foot.
However, there is a problem. The bass drum pedal connects to the drum controller with a simple mono headphone jack but just hooking up a second bass pedal with a splitter doesn't do the trick.
What we want is the ability to step on one pedal and have that trigger a bass drum hit. Then, be able to follow THAT up with another hit on the other pedal while the first one may still be down.
To do that, we need a meta-controller -- something intelligent that sits between the pedals and the controller. It watches the pedals and sends a trigger signal to the main drum controller based on what it sees.
How It Is Made
This schematic shows the circuit needed. Note that it requires its own 5V power supply - one based on the simple LM7805 should be sufficient and can be powered from a 9V battery.
You should be at least somewhat familiar with electronics to assemble this. If you don't know what a 5V power supply is or why you would need one, you're going to have trouble if you try to make one of these.
Make sure you get the 74HC14 Schmitt-Trigger Hex Inverter. The 7404 will not work. All of the diodes can be pretty much any kind. The 5V relay should be normally-open and should be non-latching. The transistor is a 2N3904, but any garden-variety NPN BJT should do.
What happens is that the closing of either input switch (i.e. either pedal) causes the output (the relay) to close for a short time, then re-open - regardless of whether the input pedal is still down or not.
This allows pedal #1 to be pushed down to trigger a Bass Drum hit, then while pedal #1 is still down, pedal #2 can be hit to trigger another Bass Drum hit! When working both pedals at once one after theother, this allows for some very fast bass drumming.
