A voltage-controlled oscillator module for modular synthesizers, offered in kit or assembled form by Aries during the mid-1970s.
Overview
The Aries AR-317 is a modular synthesizer VCO (Voltage Controlled Oscillator) sold in the mid-1970s. It has four simultaneous waveform outputs and can sync to an external square wave. It was designed for a 10V signal level standard. Six internal trimmers handle calibration of 1V/octave response, initial frequency, sawtooth amplitude and offset, and sine wave purity and symmetry. Two front panel jacks go unused, and they can be repurposed for things like a linear FM input.
Specifications
| Frequency Range (Manual Control, 2 ranges) | 0.03 Hz to 30Hz |
| Waveform Outputs | Four simultaneous outputs |
| VCO Sync | External square wave sync supported |
| Inputs/Outputs | Two unused jacks on front panel |
| Adjustments | T1 (1V/Octave), T2 (Initial Frequency), T3 (Sawtooth Amplitude), T4 (Sawtooth Offset), T5 (Sine Purity), T6 (Sine Symmetry) |
| Signal Level Design | 10V signal levels |
| Original Price (1975) | $69.50 (kit), $139.00 (assembled) |
| Original Price (1977) | $125.00 (kit), $182.00 (assembled) |
Design
The AR-317 came as a kit or as a factory-assembled module. Its PCB is single-sided tin with no solder mask, so the pads tend to lift. The exponential converter is a potted module (U8) holding three transistors and a tempco resistor, and the NPN transistor in it is known to fail. The PCB mounts in two plastic rails, secured by angle brackets and screws. Build notes suggest adding linear FM through a 330k resistor from an unused jack to pin 4 of U8, with AC coupling possible using a 0.1 µF capacitor. The unused jacks could also take AC or linear FM inputs, or small 1/8" potentiometers. Restoration reports note clean waveforms, excellent stability, and no drift. The original builds, though, show non-uniform components, wiring inconsistencies, cold joints, solder bridges, tin whiskers, and mechanical problems that caused shorts.
Market
Common problems are kit build errors, improper repairs, lifted PCB pads with cracked traces, and mechanical interference. The restorer found that the transistor pinouts on the PCB (E-B-C) conflict with the datasheet pinouts (E-C-B) for some types, like the 2N3393 and NTE85, which led to incorrect installation. NPN transistors fail more often than PNP. How well a given module performs depends heavily on the builder's skill, since most units appear to have been assembled from kits with variable quality.
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