C.Inputs
To the right are the
inputs for the module. On
the top left, we see the
Maybe and Maybe CV
pots. The voltage on the
wipers of these pots is
mixed together by the
TL072 op amps and 100K
resistor network. Before
connecting to the CV input
pin of the PIC, a 1K
resistor and a pair of
schottky diodes form a
voltage limiting circuit,
and a .01uf capacitor
filters noise.
Under the CV
inputs are the clock and
reset inputs. Each of these
is connected to an opamp on the TL074. The opamps are wired as comparators with their thresholds
set at .5V by the 10K/1K voltage divider. Each comparator has a 100K resistor to ground on it's
input, and it's output goes through a switching diode to prevent negative voltage passing from the
comparator's output to the PIC's inputs. A 100K/100K voltage divider and a schottky diode
connected to +5V prevent overvoltage from damaging the PIC's input pins.
D.Outputs
Above are the outputs. The opamps are wired as non-inverting buffers. They connect to
LEDs through a 1K current limiting resistor, to the output wirepads through a 1K output impedance
setting resistor.
