User manual

This approximately 1.15 volt threshold can also be activated by reasonably high level audio

signals.

Within a fraction of a millisecond of the input voltage going above the threshold, the

detector is activated and remains activated for about 33 msec. This means even a narrow

positive pulse waveform which reaches about +1.15 volts will turn the detector on

continually, as long as its frequency is above about 30Hz. The input can handle +/- 15 volts.

There’s no problem feeding these inputs with a continually high +15 volt CV, or any audio

or CV in this range. (It is probably fine to go to +/- 30 volts or so, but +/- 15V is the range

of most modular gear, and of line level signals in studios.)

Audio signals whose positive peaks extend to +1.15 volts are commonly found in studios

when the volume setting is maximised. Microphones and electric guitars generate smaller

signals, but some sythesizers can generate signals of this magnitude. The TB-303, Devil

Fish and TT-303 Bass Bot generally do not create signals with positive peaks in excess of

+1.15 volts, so it will often be necessary to send audio signals through a pre-amp, effects

box or a mixer channel in order to activate these detector circuits.

One or two audio or CV signals can be used to dynamically alter the memory bank the

Internal Sequencer is playing from. “Dynamic” in this context means as a result of external

audio or CV signals, not just as a result of manual actions on the toggleswitches. With the

MIDI In and Out system, if nothing is plugged into an Audio/CV Input socket, the MIDI In

and Out firmware can drive the output of the socket, and so the detector circuit, LED and

address bit inversion circuit, according to Note and/or Control Change messages received on

MIDI In Channel 15 or 16. This enables dynamic switching of both the memory bank and, if

enabled, the MIDI In channel for Notes. “Dynamic” in this context refers to the reception of

external MIDI In Note and/or Control Change messages.

Address bit inversion follows Exclusive Or (XOR) logic. Inclusive OR means “the output

is high if one or more of the inputs are high”. “High” generally means a binary

while

“low” generally means binary

. XOR gates have only two inputs. The output is high when

one or the other input is high, but not when both are high. The truth table is:

Input bits Output bit

0 0 0

0 1 1

1 0 1

1 1 0