E-480 Contour generator module for Eurorack/Doepfer A100 system

Left column:
trig/gate input + LED
rate knob + LED
first integrator time knob
first integrator output jack + polarity LEDs
second integrator time knob
second integrator ending decay knob
second integrator output jack + polarity LEDs

Right column:
8 three-position switches (down/stay/up)
offset knob

E-480 module creates control voltage based on internal clock, position of 8 switches, integration time knobs settings and offset knob setting. Can work as one-shot (sequence of all 8 steps passes once, started by rising edge of input trig/gate) or sequence can be cycled while input gate is active. One shot mode or cycled mode is jumper-selectable (top jumper, jumper header set = one-shot mode). Second (bottom) jumper can set retrig mode (unfinished sequence starts again from first step – jumper set) or disables retrig (8-step sequence must be finished first to allow retrig – jumper header removed).

Rate knob sets processing time in range from 4ms/step (32ms/cycle) to 0,5s/step (4s cycle). Switches are used for setting “direction” – where voltage should go in entire step (down/stay/up) but it depends on offset knob setting too. “Direction” voltages from switches (and offsett knob voltage partialy too) are integrated in two serial integrators, first integrator creates linear curves (integration time = steepnes is set by knob). Integration time means “how much will be step constant voltage added to integrator”, in other words time knob sets output steepnes (input voltages from switches are constant, negative, zero and positive). Say switches will be set to up/down/up/down… alternately and rate (stage time) will be constant. Then increasing integration time makes output triangles smaller (speed of output changes is more limited, integration needs more time to reach an target value). Output of first integrator is inverted, setting an switch to “up” makes falling voltage ramp on first integrator output for entire step. Generated linear signal then goes into second integrator creating exponential curves (with different integration time). Endind decay is set by last knob. Offset knob affects outputs dramatically. All variable parameters depend on each other –  if rate is set to an slow value, integration time should be set slow too else output can reach power supply and opamps voltage limits easily. If integration time is set too short (= voltage in current step stays same for long time = rate is set slow) steepness of output is high and output can reach power supply and opamps voltage limits (in real about +-10V due opamps output swing) and stays here until reverse direction in some of next step causes moving output in opposite direction. As an approximation how it works imagine 8-step CV seq, step voltages alternately set to +5V and -5V followed by linear slew limiter. If you´ll clock 8 clocks then it passes all 8 steps, seq out will be squares +-5V p-p. Output of linear slew (=integrator) will depend on slew time setting, slow slew time causes small output changes. Offset amount is integrated too so it should be set near centre as basic setting (but it is not rule). There are over 6500 switch combinations + different integration time  and offset settings…

First integrator output examples (linear):

Second integrator output examples (exponential):

E-480 can be used for generating unusual envelopes (self clocked – independent of input gate length(!) in one-shot mode) or better for creating rich attach portion of an envelope (if output CV is mixed with an “standard” envelope), as example imagine more initial peaks for say trumpet simulation. In cycle mode can be used as gated LFO creating unusual waveshapes.

Width: 8TE/ 8HP/ 40mm
Depth: 55mm /2,2″ max.
Current: 30mA max.
Power cable included

Double check power connection before powering your system please.
„Red strip“ means -12V connector side in Eurorack standards.
In some power distribution systems connector key can be reverted.
In this case cut connector key and plug power connector right way (with respect to red strip) or use different power cable appropriate to your power system