ARP 1004-T Voltage Controlled Oscillator (VCO)
A modular oscillator with dual triangle and sawtooth cores, manual sync via panel switch, and shared circuitry across multiple ARP modules.
Overview
The ARP 1004-T is a Voltage Controlled Oscillator (VCO) module designed for modular synthesizer systems. It features both triangle and sawtooth waveforms, with the sawtooth core reset by the square wave derived from the triangle oscillator. Sync is controlled manually via a front-panel "inhibit" switch; there is no external input to trigger reset. The module is built from two printed circuit boards: the main 1004 VCO board and a dedicated "T" waveform selector board.
Specifications
| Product Type | Voltage Controlled Oscillator module |
| Boards | Main 1004 VCO board and "T" waveform selector board |
| Waveforms | Triangle and sawtooth |
| Sync Function | Manual reset via panel switch (no external input) |
Design
The 1004-T uses a dual-core oscillator design where the sawtooth wave is synchronized by the square wave output generated from the triangle core. The main 1004 VCO board is shared with other ARP modules, including the 1023 Dual Oscillator and the 1045 Voltage Controlled Voice module. The main board includes components such as transistors (TZ-81, TZ-581, 2N5460), ICs (1339, LM301AH), potted exponential modules (4001-003, 4002-003), and a range of resistors and capacitors with specific values. The "T" waveform selector board includes 2N5460 transistors, 1339 ICs, and components including 2200 pF and 0.01 µF capacitors, and resistors such as 390 Ω, 1 kΩ, 10 kΩ, 47 kΩ, and 100 kΩ.
Context
The main 1004 VCO board is used in the 1004-P, 1023 Dual Oscillator, and 1045 Voltage Controlled Voice module, indicating its role as a common oscillator platform in ARP’s modular synthesizer system.
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