Cabinet 1 Reference
OGEE is built in two cabinets, on four 7" high rack panels.
| Module | Front Panel | Features | Schematic Reference |
|---|---|---|---|
| Power Supplies | +/- 15 volts at 1 amp, +5 volts at one amp, in each cabinet. | ||
| VCO's 1, 2, 3 | |
Saw, Tri, Pulse outputs. PWM and Linear FM inputs. Hard and soft sync, LFO switch. Based on SSM2033 chip | |
| VCA 1, 2 | |
AC and DC coupled inputs, exponential and linear control, gain control. Based on CES 3330 dual VCA chip. | Schematic |
| ADSR 1, 2, 3 | |
Transient Generator with Attack, Decay, Sustain, Release and Output Level controls. Gate and trigger inputs, manual trigger button. Based on CES 3310 ADSR chip. | Schematic |
| Low Frequency Oscillator | |
LFO with Triangle, Sine, and Pulse Outputs. | Schematic |
| Psuedo Random Noise Source | |
Digital psuedorandom noise source with switchable internal or external clocks, white or pink noise outputs. Digital portion based on Electronotes EN-76 design, analog portion my own design. | Schematic |
| Sample and Hold | |
Based on PMI SMP-10, with internal or external clock. Internal clock is a 566 based VCO. | Schematic |
| 4 pole Bandpass VCF | |
Voltage controlled bandpass with voltage controlled Q adjustable into oscillation. Two tracking and one reverse (inverted) C.V. inputs, Q adjust, Initial Frequency controls. Based on CES 3320 VCF chip. | Schematic |
| 4 pole Lowpass VCF | |
Voltage controlled 4 pole lowpass with voltage controlled Q adjustable into oscillation. Two tracking and one reverse (inverted) C.V. inputs, Q adjust, Initial Frequency controls. Based on CES 3320 VCF chip. | Schematic |
| Multimode Filter | |
Voltage controlled State Variable filter with bandpass, lowpass, highpass, and notch outputs, Q control. Based on CES 3320 VCF chip. | Schematic |
| Balanced Modulator | |
Four quandrant multiplier built from two summed two quadrant multipliers (OTA's). AC coupled inputs. | Schematic |
| Voltage Controlled Pan | |
Pans input to left and right outputs based on control voltage or Position control. | Schematic |
| Reverb | |
Spring reverb module. | Schematic |
| Mixer | |
Four input mixer with switchable stereo or mono outputs, individual attenuators and left-right gain, two line outputs and headphone output with bass boost. | Schematic |
| Module | Front Panel | Features | Schematic Reference |
|---|---|---|---|
| Keyboard Interface | Keyboard connected by 5 pin DIN connector. This module provides multiple control voltage, gate, and trigger outputs, plus some variable (pot controlled) DC control voltages. | ||
| 16 event Sequencer |  |
16 event analog sequencer multiplexes 16 10 turn pots. Internal or external clock, Step, Single Run, and Run modes. Original design. | Schematics |
| Envelope Follower |  |
0db and +20db inputs, gain control, envelope, gate, and trigger outputs. Uses cascaded envelope follower design from Electronotes EN-88 and EN-89. | Schematic |
| Multiplexer |  |
4 input, one output MUX. Internal or external clock, rate control, single step button. Original design. | Schematic |
| Voltage Controlled Analog Delay Line |  |
Never quite got this one working (notice the holes). Future project. | |
| Waveform Animator | From Electronotes EN-87. Sort of a PWM for saw and triangle waveforms. Output looks real interesting on a scope. | Notes | |
| Timbre Modulator |  |
From Electronotes EN-72. | Schematic |
| Voltage Controlled Transient Generator |  |
ADSR with control voltage inputs for Delay, Attack, Decay, Sustain, and Release. Based on CES 3310 chip with added circuitry to provide voltage control. | Schematic |
| VCO4 |  |
VCO with saw, pulse, triangle, sine, and suboctave square outputs. The suboctave has a fixed rate Pulse width modulation. Hard and soft sync, linear FM and control voltage inputs, LFO switch. Based on SSM 2033 VCO chip. | Schematic |
| Variable Slope Filter |  |
From Electronotes EN-72. Built this without knowing what a variable slope filter would sound like. I wasn't too impressed; it sounds like a 2 pole lowpass. | |
| Switched Capacitor (Commutating) Filter |  |
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| VCA 3, 4 | |
AC and DC coupled inputs, exponential and linear control, gain control. Based on CES 3340 dual VCA chip. | Schematic |
You may notice there is no keyboard mentioned. Originally I had built a 5 octave low note priority scanned keyboard with portamento and joystick controlled pitch bend, but it got trashed. Future project: Build a Midi to CV interface (probably will just buy a kit).