Space Adventure Keyboard bending guide

Pete of Casper Electronics has burned through quite a bit of midnight oil bending this beast and taking notes. Now we all can learn from his findings. Thanks. From Pete," This keyboard has five separate circuit boards. -Control interface board -Keyboard audio circuit -Power/amp board -“space” sound fx circuit -Blinking light sequencer circuit (really just a simple decade counter circuit) The largest one is just the CONTROL INTERFACE. This holds all of the function and piano key buttons. This connects to the keyboard audio circuit with a ribbon cable. The KEYBOARD AUDIO CIRCUIT is the keyboards “brain”. It processes the pushbutton matrix (signals from the control interface board) and generates the main keyboard audio signals. There is a trim pot on this board which controls the keyboard pitch. This circuit is connected to the POWER/AMP BOARD with another ribbon cable.This mixes the keyboard audio signal with the “space” fx signal and sends the signal to an amplifier. It then takes that signal and sends it to a simple envelope follower type circuit which powers the light sequencer circuit in conjunction with the amplitude of the audio signal. The LIGHT SEQUENCER circuit receives an incoming signal from the voltage/amp board and activates five different lights in sequence. The rate of the sequence can be adjusted by removing a resistor from the board and replacing it with a 1M potentiometer. The “SPACE” FX circuit is a completely separate circuit. Both the pitch and volume of this circuit can be adjusted independently of the keyboard. PITCH CONTROL You can make some pretty crazy warbling, screeching sounds by lowering the pitch. It also does some cool stuff when you raise the pitch. Raising it to the right level will create amazing glitch effects that work extremely well with the drum beats and demo songs. The tricky part is that there’s a very small pitch window in which this glitch will work and if you turn the pitch up too high, the circuit will crash. For this reason, I built in coarse, mid and fine tune pitch adjustments. This allows the user to very finely adjust the pitch and take advantage of the glitch feature. I also added a pitch calibrating board for fine tuning the pitch range so that it can’t be turned too high or low. LIGHT SEQUENCER The light sequencer circuit board outputs a voltage signal to each of the five lights in sequence (one at a time) when the keyboard is making sound. By taking the signal which powers the lights and routing that to the keyboard pitch control pin, you can modulate the pitch. Unfortunately the signal cannot power the light AND change the pitch at the same time. It CAN but there are lots of problems that are caused by doing this (just trust me). Because of this I installed a button which switches between “light mode” and “pitch mode”. Each of the five steps of the sequence has an on/off switch and a pitch control adjustment. I also added a sequence rate adjustment and a total pitch depth adjustment. By setting each step adjustment to different points and switching the sequencer to “pitch mode” you can make some interesting modulated sequences. “REPLAY” TRIGGER The keyboard has a built in record and replay feature. This allows the user to record short melodies and play them back. I added a circuit to the keyboard that allows the user to trigger the “replay” function using an external controller. There are two input jacks. One is for a switch, like a foot pedal, the other is for voltage pulse signals, like an LFO or gate signal from an analog synth. The circuit itself is a simple transistor and opto isolator circuit. The incoming signal activates two transistors. One turns on an LED (so that you can monitor the incoming signal) the other powers an opto isolator which then activates the “replay” function. To do this I simply connected two wires to the points on the control interface board that are connected to the “replay” pushbutton contacts and wired them to the opto isolator." Sound Sample 1 Sound Sample 2 Sound Sample 3